Methods and devices for endovascular ablation of splanchnic nerves

Abstract

Systems, devices, and methods for transvascular ablation of target tissue. The devices and methods may, in some embodiments, be used to increase blood capacitance in splanchnic veins by splanchnic nerve ablation to treat at least one of heart failure and hypertension. For example, the devices disclosed herein can be navigated intravascularly to target vessels in the territory of the thoracic splanchnic nerves (TSN) (e.g., the greater splanchnic nerve (GSN) or TSN nerve roots). Additionally, methods are disclosed for treating heart failure (e.g., HFpEF) by endovascularly ablating the thoracic splanchnic nerves to increase venous capacitance and reduce pulmonary blood pressure.

Description

[Technical Field]

[0001] Literature citations This application claims priority to U.S. Provisional Patent Application No. 62 / 962,627, filed January 17, 2020, and U.S. Provisional Patent Application No. 63 / 086,516, filed October 1, 2020, the disclosures of which are incorporated herein by reference in their entireties for all purposes.

[0002] All publications and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference.

[0003] This disclosure relates, by subject matter, to U.S. Provisional Patent Application No. 62 / 864,093 filed June 20, 2019, U.S. Provisional Patent Application No. 62 / 881,251 filed July 31, 2019, U.S. Provisional Patent Application No. 62 / 962,627 filed January 17, 2020, U.S. Patent Publication Nos. 2019 / 0175912, 2019 / 0183569, U.S. Patent Nos. 10,376,308, 10,207,110, and 16 / 510,515. Nos. 62 / 836,720, 62 / 837,090, 62 / 864,093, International Application Nos. PCT / US2019 / 15400, PCT / US2020 / 038934, International Publication Nos. WO2018 / 023132, WO2019 / 118976, and WO / 2020 / 257763, all of which are incorporated herein by reference in their entireties for all purposes. [Background technology]

[0004] Heart failure (HF) is a medical condition that occurs when the heart cannot pump enough to maintain the body's organs. Heart failure is a serious condition that affects millions of patients in the United States and worldwide.

[0005] One common indicator of cardiac health is the left ventricular ejection fraction (LVEF) or ejection fraction. By definition, the volume of blood in the ventricle just before contraction is called the end-diastolic volume (EDV). Similarly, the volume of blood remaining in the ventricle at the end of contraction is the end-systolic volume (ESV). The difference between EDV and ESV is the stroke volume (SV). SV represents the volume of blood ejected from the right and left ventricles with one heartbeat. Ejection fraction (EF) is the percentage of EDV ejected with one heartbeat and is calculated by dividing SV by EDV. Cardiac output (CO) is defined as the volume of blood pumped by each ventricle of the heart per minute. CO is equal to SV multiplied by the heart rate (HR).

[0006] Cardiomyopathy, in which the heart muscle becomes weak, stretched, or exhibits other structural problems, may be further classified as systolic or diastolic dysfunction based on ventricular ejection fraction.

[0007] Although several pharmacologic therapies have successfully targeted systolic dysfunction and HFrEF, promising treatments remain elusive for the large group of patients with diastolic dysfunction and HFpEF. The clinical course of patients with both HFrEF and HFpEF is significant with regard to the recurrent development of acute decompensated heart failure (ADHF), which is associated with symptoms such as dyspnea, decreased exercise capacity, and peripheral edema. Recurrent hospitalizations for ADHF utilize a large portion of current healthcare resources and may continue to incur significant costs.

[0008] Although the pathophysiology of HF is becoming increasingly better understood, modern medicine has so far been unsuccessful in developing new therapies for the chronic management of HF or recurrent ADHF episodes. ADHF management and prevention strategies continue to focus on the classical decades-old paradigm that salt and water retention are responsible for intravascular fluid expansion and cardiac decompensation.

[0009] Thus, there is a continuing need for improved, safe and effective therapies for heart failure patients, as well as devices and systems adapted and configured to deliver those therapies. Summary of the Invention [Problem to be solved by the invention]

[0010] The present invention has been made to solve the problems in the prior art described above. [Means for solving the problem]

[0011] The present disclosure relates to methods, devices, and approaches for ablating thoracic splanchnic nerves or thoracic splanchnic nerve roots. Ablation can be performed to treat hypertension and / or heart failure, although the general method may be used for other treatments. For example, the methods described herein can be used to treat pain and also to provide general patient benefit by reducing the amount of blood draining from the splanchnic bed into the central thoracic vein.

[0012] The treatments described herein can be achieved by increasing splanchnic capacitance and generally involve ablating a patient's preganglionic thoracic splanchnic nerves or thoracic splanchnic nerve roots to increase splanchnic capacitance, thereby treating at least one of hypertension and heart failure.

[0013] The methods described herein describe ablating thoracic splanchnic nerves, e.g., the greater splanchnic nerve or the greater splanchnic nerve root. While the methods described herein may provide specific examples of targeting the greater splanchnic nerve or the greater splanchnic nerve root, it may alternatively or additionally be possible to ablate other thoracic splanchnic nerves (e.g., the lesser splanchnic nerve, the least splanchnic nerve) to perform one or more of the treatments described herein.

[0014] One aspect of the present disclosure is a method of ablating tissue by intravascularly positioning a medical device near a target tissue and using the medical device to ablate the tissue and create a lesion. One aspect of the present disclosure is a method of ablating tissue by intravascularly positioning a medical device within one or more target blood vessels and using the medical device to ablate the tissue and create a lesion. Accordingly, the methods described herein can be described as methods of positioning a medical device near a target tissue to be ablated and / or methods of positioning a medical device within one or more blood vessels, where the target tissue is relatively close to a target region within the one or more blood vessels. Any of the method steps described herein (including, by way of example and not limitation, those in the claims or the "Description of Embodiments" section) can be incorporated into any other method of use described herein, unless specifically indicated to the contrary herein.

[0015] One aspect of the present disclosure is a method for ablating a greater splanchnic nerve or greater splanchnic nerve root to increase splanchnic nerve blood capacitance and / or venous compliance, the method comprising the steps of advancing a medical device into a first blood vessel, advancing at least a portion of the medical device into a second blood vessel, and delivering ablation energy from the medical device to create damage in tissue surrounding the first blood vessel.

[0016] In some embodiments, the first blood vessel is an azygos vein and the second blood vessel is an intercostal vein. The intercostal vein may be one of the three lowest intercostal veins. The intercostal vein may be a T9, T10, or T11 intercostal vein.

[0017] The method may include positioning a distal end of the ablation element within the second blood vessel within 30 mm (e.g., 20 mm, 15 mm, 12 mm) of the junction of the first blood vessel and the second blood vessel when delivering energy from the ablation element.

[0018] The method may include positioning a proximal portion of the ablation element within the second blood vessel during energy delivery.

[0019] The method may include aligning or positioning the ablation element relative to a bony landmark (eg, a costovertebral joint at the same vertebral level as a second blood vessel (eg, an intercostal vein)).

[0020] In some embodiments, aligning or positioning the ablation element relative to a bony landmark (eg, costovertebral joint) includes viewing the bony landmark through medical imaging, such as fluoroscopy.

[0021] In some embodiments, displaying the bony landmarks using medical imaging, such as fluoroscopy, includes orienting the medical imaging fluoroscopic view toward the side of the patient where the target nerve is located at an anterior oblique angle in the range of 25-65° from AP (e.g., in the range of 30-60°, in the range of 35-55°).

[0022] In some embodiments, displaying the bony landmark with medical imaging, such as fluoroscopy, includes orienting the medical imaging fluoroscopic view approximately perpendicular to a line between a first blood vessel (e.g., the azygos vein) and the bony landmark (e.g., the costovertebral joint) of the patient.

[0023] In some embodiments, aligning the ablation element relative to the bony landmark includes aligning a radiopaque marker disposed on a catheter containing the ablation element with the bony landmark.

[0024] The method may include creating a lesion at a distance of 5 mm around the ablation element. Creating the lesion may include ablating a portion of a thoracic splanchnic nerve or thoracic splanchnic nerve root (e.g., the greater splanchnic nerve or the GSN root). The lesion may be a continuous lesion. The length of the lesion may be 5 to 25 mm, e.g., 10 to 25 mm, e.g., 15 to 20 mm. The lesion may be a circumferential lesion that extends completely around the second blood vessel. However, the lesion may be a circumferential lesion that extends less than the entire circumference around the second blood vessel, e.g., a circumferential lesion that extends less than 225 degrees, 180 degrees, 135 degrees, 90 degrees, or 45 degrees of the circumference.

[0025] The method may include positioning the entire ablation element within the second blood vessel, while the method may also include positioning less than the entire length of the ablation element within the second blood vessel.

[0026] The method may include performing the ablation process from within two or more target vessels (e.g., an intercostal vein or an azygos vein). The ablation methods described herein may also be performed within a second vessel.

[0027] The method may include performing an ablation confirmation test (e.g., any of the tests described herein). If desired or necessary, the ablation element may be repositioned into a second target vessel, which may be the azygos vein or another intercostal vein.

[0028] The method may also include delivering stimulation energy to first and second stimulation electrodes carried by the medical device before, during, and / or after delivery of the ablation energy. The delivery of the stimulation energy may aid in determining whether the ablation element is at a target location within the intercostal vein and / or whether the ablation procedure was effective.

[0029] One aspect of the present disclosure is a method comprising delivering an ablation catheter including an energy delivery element (or member) through a patient's venous system; positioning at least a portion (optionally the entirety) of the energy delivery element within a vein selected from the T9, T10, and T11 intercostal veins; and delivering ablation energy from the energy delivery element to create a contiguous lesion at least 5 mm deep and 10-25 mm long. The contiguous lesion and its parameters may be formed by selecting specific energy delivery parameters to create the lesion. In some embodiments, the lesion may extend from the ostium of the azygos vein along the intercostal veins for up to 20 mm. Any of the other method steps described herein may be implemented in this exemplary method, even if described in the context of other methods.

[0030] In some alternative methods described herein, multiple ablations (i.e., ablation from ablation energy on to ablation energy off) may be performed within a single target vessel (e.g., an intercostal vein) to create an overall lesion comprised of two or more lesions created from multiple ablations. The overall lesion comprised of multiple lesions may have any of the characteristics of other lesions described herein. For example, the overall lesion may be contiguous (e.g., stitched together from lesions created by different ablations), up to 20 mm in length, circumferential (or non-circumferential), or have other characteristics. After a first ablation, the ablation device may be moved within the same vessel to create a second lesion, which may or may not overlap the first lesion. This may be repeated as many times as necessary. Any of the stimulating or testing steps described herein may be performed before, during, or after any ablation step, even when multiple ablations are performed within a single vessel.

[0031] One aspect of the present disclosure is a method of positioning an ablation catheter at a location within a T9, T10, or T11 intercostal vein for ablation of a great splanchnic nerve (GSN), the method including the steps of imaging a portion of a patient including at least one of the T9, T10, or T11 intercostal vein and a portion of the patient's spine, positioning a distal portion of the ablation catheter in the T9, T10, or T11 intercostal vein, and positioning an ablation catheter radiopaque marker at a location based on the position of the radiopaque marker relative to an anatomical landmark (e.g., one or more of a portion of the spine, a rib, a costovertebral joint, an azygos vein, or a venous ostium between the azygos vein and the T9, T10, or T11 intercostal vein). The method may further include delivering energy from the ablation catheter ablation element to ablate tissue.

[0032] One aspect of the present disclosure is a method that includes characterizing the relative position of a patient's azygos vein to determine whether the azygos vein is centrally or nearly centrally located, right-biased (to the right of the patient's center), or left-biased (to the left of the patient's center). The characterizing step may be performed from a particular perspective that allows the characterization to be performed accurately while displaying a particular portion of the patient's anatomy. The method may further include positioning an ablation catheter based on the characterizing step.

[0033] One aspect of the present disclosure is a method for characterizing the position of a patient's azygos vein relative to a portion of the patient's spine, the method including the steps of imaging at least a portion of the patient's spine and vasculature (particularly, the azygos vein and / or one or more intercostal veins) using an imaging device (particularly, using a radiographic imaging device that injects a radiopaque contrast agent into the patient's vasculature) or imaging at least one radiopaque device (the radiopaque device optionally comprising a radiopaque portion of a guidewire) positioned within the azygos vein and / or one or more intercostal veins relative to the portion of the spine using an imaging device (particularly, using a radiographic imaging device) to characterize the position of the patient's azygos vein relative to the midline of the spine, and determining whether the azygos vein is centered, left-offset, or right-offset with respect to the vertebral midline based on one or more images produced by the imaging device. This aspect further includes a method for determining an appropriate location in the vascular system of a human patient to insert a catheter (particularly to enable ablation of a greater splanchnic nerve or greater splanchnic nerve root), the method including determining where to place an ablation element of a transvascular ablation catheter (particularly any of the ablation catheters described herein) based on the above determination of whether the azygos vein is centered, left-biased, or right-biased relative to the vertebral midline.

[0034] This aspect may further include a step of determining where to place a radiopaque marker carried on a distal portion of the ablation catheter (optionally a proximal radiopaque marker located proximal to any ablation elements carried on the same distal portion) based on the above determination of whether the azygos vein is centered, left-biased, or right-biased relative to the vertebral midline.

[0035] One aspect of the present disclosure is a method for determining proper positioning of a catheter (optionally a catheter according to any of the claims or disclosures herein) for insertion into the vascular system of a human patient, the catheter comprising an elongate shaft having a distal portion carrying one or more ablation elements and a proximal radiopaque marker, the distal portion of the elongate shaft being positioned within a T9, T10, or T11 intercostal vein, the method comprising the steps of determining whether the azygos vein is centered, left-offset, or right-offset relative to the vertebral midline; The method includes the steps of evaluating the position of the proximal radiopaque marker and verifying whether the catheter is correctly positioned relative to the patient's anatomical landmarks, wherein the verifying step includes deeming the catheter correctly positioned if one of the following situations occurs: the proximal radiopaque marker is located at the ostium of an intercostal vein to the right of the vertebral midline if the azygos vein is deviated to the right; or the proximal radiopaque marker is aligned with the vertebral midline if the azygos vein is centered or deviated to the left.

[0036] In any of the method aspects described herein, the proximal radiopaque marker may be carried on the distal portion and may be located proximal to all of the ablation elements, the proximal radiopaque marker may be located immediately proximal to the ablation elements, or the proximal-most ablation element carried on the distal portion of the catheter.

[0037] In any of the method aspects described herein, the catheter may include a distal radiopaque marker located distal to all of the ablation elements, and the verifying step further includes assessing the position of the distal radiopaque marker relative to the patient's costovertebral joints and / or ribs, and confirming that the distal radiopaque marker is spaced from the costovertebral joints and / or ribs by at least a predetermined threshold distance. The distal radiopaque marker may be located immediately distal to the ablation elements or immediately distal to the most distal ablation element carried on the distal portion of the catheter, and the confirming step includes confirming that the distal radiopaque marker is at least 3 mm, preferably at least 5 mm, from the costovertebral joint.

[0038] In any of the method aspects described herein, the verifying step may include deeming the catheter to be incorrectly positioned if none of the following conditions occur: the proximal radiopaque marker is located at the ostium of an intercostal vein to the right of the vertebral midline if the azygos vein is deviated to the right; or the proximal radiopaque marker is aligned with the vertebral midline if the azygos vein is centered or deviated to the left.

[0039] In any of the method aspects described herein, if it is determined that the catheter is not positioned correctly, the method may further include adjusting the position of the catheter by aligning a proximal radiopaque marker on the ablation catheter with a respective anatomical landmark and / or by moving a distal radiopaque marker further away from the costovertebral joint.

[0040] In any of the method aspects described herein, determining whether the azygos vein is centered, left-biased, or right-biased relative to the vertebral midline may include imaging at least a portion of the patient's spine and vasculature (particularly the azygos vein and / or one or more intercostal veins) using an imaging device (particularly using a radiographic imaging device that injects a radiopaque contrast agent into the patient's vasculature), or imaging at least one radiopaque device (the radiopaque device optionally including a radiopaque portion of a guidewire) positioned within the azygos vein and / or one or more intercostal veins relative to a portion of the spine using an imaging device (particularly using a radiographic imaging device) to characterize the position of the patient's azygos vein relative to the spinal midline.

[0041] In any of the method aspects described herein, the step of assessing the position of the proximal radiopaque marker relative to the vertebral midline may include imaging at least a portion of the catheter including the proximal radiopaque marker using an imaging device (particularly using a radiological imaging device).

[0042] In any of the method aspects described herein, assessing the position of the distal radiopaque marker relative to the costovertebral joint may include imaging at least a portion of the catheter including the distal radiopaque marker using an imaging device (particularly using a radiological imaging device).

[0043] One aspect of the present disclosure is a method for determining whether a catheter (optionally a catheter according to any of the claims or disclosures herein) inserted into the vascular system of a human patient is properly positioned, the catheter comprising an elongate shaft having a distal portion carrying one or more ablation elements and a distal radiopaque marker, the distal portion of the elongate shaft being positioned within a T9, T10, or T11 intercostal vein, the method comprising: determining a position of the distal radiopaque marker relative to the patient's costovertebral joint; and verifying whether the catheter is correctly positioned relative to the patient's anatomical landmarks, the verifying including deeming the catheter correctly positioned if the distal radiopaque marker is spaced from the costovertebral joint by at least a predetermined threshold distance. The distal radiopaque marker may be located just distal to the ablation element, or just distal to the most distal ablation element carried on the distal portion of the catheter, with the predetermined threshold distance being at least 3 mm, preferably at least 5 mm.

[0044] In this aspect, the method may further include adjusting the position of the catheter by moving the distal radiopaque marker further away from the costovertebral joint if it is determined that the catheter is not correctly positioned.

[0045] In this aspect, identifying the location of the distal radiopaque marker relative to the patient's costovertebral joint may include imaging at least a portion of the patient's spine and vasculature (particularly the azygos vein and / or one or more intercostal veins) using an imaging device (particularly using a radiographic imaging device that injects a radiopaque contrast agent into the patient's vasculature), or imaging at least one radiopaque device (the radiopaque device optionally including a radiopaque portion of a guidewire) positioned within the azygos vein and / or one or more intercostal veins relative to a portion of the spine using an imaging device (particularly using a radiographic imaging device) to characterize the location of the patient's azygos vein relative to the midline of the spine, and imaging at least a portion of the catheter including the distal radiopaque marker using an imaging device (particularly using a radiographic imaging device).

[0046] One aspect of the present disclosure is an ablation catheter for transvascular ablation of thoracic splanchnic nerves, particularly for ablating the greater splanchnic nerves or greater splanchnic nerve roots, comprising an elongate shaft having a length such that a distal portion of the elongate shaft can be placed within the T9, T10, or T11 intercostal vein, and a proximal conductive flexible ablation element and a distal conductive flexible ablation element mounted on the distal portion of the elongate shaft, the length from the distal end of the distal ablation element to the proximal end of the proximal ablation element being 10 to 25 mm.

[0047] In this embodiment, the distal portion of the elongate shaft may have an outer diameter of 1.5 to 3 mm.

[0048] In this embodiment, there may be an axial spacing between the proximal and distal ablation elements, which is between 0.1 and 5 mm, such as between 0.1 and 3 mm, such as between 0.1 and 2 mm, such as between 5 and 1 mm.

[0049] In this aspect, the distal and proximal ablation elements may be electrodes.

[0050] In this aspect, the distal and proximal ablation elements may be of the same length.

[0051] In this aspect, the distal and proximal ablation elements do not have to be the same length.

[0052] In this embodiment, the distal and proximal ablation elements may each be 5-12 mm in length, such as 6-10 mm, such as 7-9 mm, or any length within any of these ranges.

[0053] In this embodiment, the distal ablation element can have a helical configuration, and the proximal ablation element can have a helical configuration. The helical configurations of the distal and proximal ablation elements can be the same. The helical configurations of the distal and proximal ablation elements can have one or more different characteristics, such as one or more of the coil orientation (e.g., left-handed or right-handed), pitch, or thickness.

[0054] In this aspect, the distal and proximal ablation elements may each have a curvilinear cross-sectional configuration.

[0055] In this aspect, the distal and proximal ablation elements may each have a rectilinear cross-sectional configuration.

[0056] In this aspect, the distal and proximal ablation elements may be made from a superelastic material such as Nitinol.

[0057] In this embodiment, the distal and proximal ablation elements may have sufficient flexibility and size to allow the distal portion to be advanced through the azygos vein and into one of the T9, T10, or T11 intercostal veins.

[0058] In this aspect, the distal and proximal ablation elements may be affixed to the distal and proximal end regions of the shaft, respectively, but may not be affixed between the distal and proximal end regions.

[0059] In this aspect, the catheter may further include a radiopaque marker. The radiopaque marker may be positioned distal to the distal end of the distal ablation element. The radiopaque marker may be positioned 0-5 mm (optionally 0-3 mm, or 0-2 mm) distal to the distal end of the distal ablation element. The radiopaque marker may be positioned proximal to the proximal end of the proximal ablation element. The radiopaque marker may be positioned 0-5 mm (optionally 0-3 mm, or 0-2 mm) proximal to the proximal end of the distal ablation element.

[0060] In this aspect, each of the distal and proximal ablation elements is not configured to deploy to a deployed configuration.

[0061] In this aspect, the distal and proximal ablation elements each have an operational configuration that is the same as or nearly the same as the delivery configuration.

[0062] In this aspect, the distal ablation element and the proximal ablation element each have an outer diameter in the operational state that is the same as or approximately the same as the outer diameter in the delivery state.

[0063] In this aspect, the distal and proximal ablation elements may each have an expanded configuration that is different from the delivery configuration.

[0064] In this aspect, the catheter may further include a temperature sensor mounted on the shaft. The temperature sensor may be located at the distal end of the distal ablation element. The temperature sensor may be located at the proximal end of the proximal ablation element. The catheter may include a second temperature sensor, the temperature sensor located at the distal end of the distal ablation element and a second temperature sensor located at the proximal end of the proximal ablation element.

[0065] In this aspect, the catheter may further include one or more irrigation ports in fluid communication with the irrigation lumen, the irrigation lumen being connectable to a fluid source at the proximal portion of the ablation catheter. One of the one or more irrigation ports may be axially located between the distal and proximal ablation electrodes. Optionally, none of the one or more irrigation ports may be located radially below the ablation element structure. The one or more irrigation ports may be located between the helical windings of the distal and proximal ablation electrodes. In a side view, an irrigation port may be located between every adjacent pair of distal and proximal ablation element helical portions of the ablation element.

[0066] In this manner, the distal and proximal ablation elements may be electrically configured to be individually energized in a monopolar mode.

[0067] In this manner, the distal and proximal ablation elements may be electrically configured to be energized in a bipolar mode.

[0068] In this embodiment, the distal portion may be within 7 cm of the distal tip of the ablation catheter.

[0069] In this embodiment, the distal and proximal ablation elements may be sized and adapted to create a continuous ablation in the range of 5-25 mm (eg, 10-25 mm, eg, 15-20 mm) in length.

[0070] In this embodiment, the distal portion may be adapted to flexibly traverse the bends from the azygos vein to the T9, T10, or T11 intercostal veins.

[0071] In this aspect, the catheter may further include a guidewire lumen within the elongate shaft and having a distal port at the distal tip of the catheter.

[0072] In this aspect, the distal and proximal ablation elements may each comprise one or more of an RF ablation electrode, a coiled wire electrode, a laser cut RF electrode, a conductive ink printed RF electrode, an RF electrode on an inflatable balloon (e.g., conductive ink, flexible circuit), a conductive membrane RF electrode, an RF electrode on an inflatable cage or mesh, an ultrasonic ablation transducer, an electroporation electrode, a cryoablation element, or a virtual RF electrode.

[0073] In this aspect, the distal ablation element and the proximal ablation element may each be adapted and configured to deliver ablation energy circumferentially to create a circumferential lesion.

[0074] One aspect of the present disclosure is an ablation catheter for transvascular ablation of thoracic splanchnic nerves, particularly for ablating the greater splanchnic nerves or greater splanchnic nerve roots, comprising: an elongate shaft having a length such that a distal portion of the elongate shaft can be placed within a T9, T10, or T11 intercostal vein; an electrically conductive, flexible ablation element carried on the distal portion of the elongate shaft, the ablation element having a length of 10 to 25 mm; and a radiopaque marker carried on the elongate shaft.

[0075] In this embodiment, the distal portion of the elongate shaft may have an outer diameter of 1.5 to 3 mm.

[0076] In this embodiment, the radiopaque marker carried by the elongate shaft can be positioned 0-5 mm (e.g., 0-4 mm, or 0-3 mm, or 0-2 mm) from the end of the ablation element. The end can be the distal end of the ablation element. The end can be the distal end of a distal ablation electrode, and the ablation element can further include a proximal ablation electrode axially spaced from the distal ablation electrode.

[0077] In this embodiment, this end may be the proximal end of the ablation element.

[0078] In this aspect, the catheter may further include a second radiopaque marker carried on the elongate shaft and positioned 0-5 mm (e.g., 0-4 mm, 0-3 mm, or 0-2 mm) from the second end of the ablation element.

[0079] In this aspect, the ablation element may include a distal ablation electrode and a proximal ablation electrode, the radiopaque marker may be distal to the distal ablation electrode, and the catheter may include a second marker proximal to the proximal ablation electrode.

[0080] In this embodiment, the radiopaque marker may be placed 0-3 mm (optionally 1 mm) from the end of the ablation element.

[0081] In this embodiment, the ablation element may include a proximal ablation electrode and a distal ablation electrode axially spaced apart from the proximal ablation electrode. The distal and proximal ablation electrodes may or may not be the same length. The distal and proximal ablation electrodes may each have a length of 5-12 mm. The distal and proximal ablation electrodes may be axially spaced apart by 0.1-5 mm (e.g., 0.1-3 mm, optionally 0.5-1 mm). The distal and proximal ablation elements in this embodiment may be any of the distal and proximal ablation elements (e.g., coiled elements) described herein. In this embodiment, the cross-sectional profile of the distal ablation electrode may differ from the cross-sectional profile of the proximal ablation electrode. The distal and proximal ablation electrodes may be made of a superelastic material, such as Nitinol. The distal and proximal ablation electrodes may be sufficiently flexible to allow the distal portion to be advanced through the azygos vein and into one of the T9, T10, or T11 intercostal veins.

[0082] In this aspect, the ablation elements may not be configured to deploy to a deployed configuration.

[0083] In this aspect, the ablation element may have an operational configuration that is the same as or nearly the same as the delivery configuration.

[0084] In this manner, the distal portion may have a straight rest configuration.

[0085] In this aspect, the ablation element has an outer diameter in the operational state that is the same as or approximately the same as the outer diameter in the delivery state.

[0086] In this aspect, the catheter may further include one or more temperature sensors mounted on the shaft. The temperature sensor may be located at the distal end of the ablation element. The temperature sensor may be located at the proximal end of the ablation element. The catheter may further include a second temperature sensor, which may be located at or near the distal end of the ablation element and a second temperature sensor, which may be located at or near the proximal end of the ablation element.

[0087] In this aspect, the catheter may include one or more irrigation ports in fluid communication with the irrigation lumen, the irrigation lumen being connectable to a fluid source at the proximal portion of the ablation catheter and including any of the one or more irrigation ports described herein. One of the one or more irrigation ports may be axially located between the distal ablation electrode and the proximal ablation electrode. Optionally, none of the one or more irrigation ports may be located radially below the ablation element structure. The one or more irrigation ports may be located between the windings of the distal ablation electrode and the proximal ablation electrode, and none of the one or more irrigation ports may be located radially below the ablation element structure. In a side view, an irrigation port may be located between every adjacent pair of helical portions of the ablation element.

[0088] In this aspect, the ablation elements may include a first ablation element and a second ablation element, each of which may be electrically configured to be individually energized in a monopolar mode.

[0089] In this aspect, the ablation elements may include a first ablation element and a second ablation element, which may be electrically configured to be energized in a bipolar mode.

[0090] In this embodiment, the distal portion may be within 7 cm of the distal tip of the ablation catheter.

[0091] In this embodiment, the ablation element may be adapted to create an ablation that is in the range of 10-25 mm (eg, 15-20 mm) in length.

[0092] In this embodiment, the distal portion may be adapted to flexibly traverse the bends from the azygos vein to the T9, T10, or T11 intercostal veins.

[0093] In this aspect, the catheter may further include a guidewire lumen within the elongate shaft and having a distal port at the distal tip of the catheter.

[0094] In this aspect, the ablation element may include one or more of an RF ablation electrode, a coiled wire electrode, a laser cut RF electrode, an RF electrode printed with conductive ink, an RF electrode on an inflatable balloon (e.g., conductive ink, flexible circuit), a conductive membrane RF electrode, an RF electrode on an inflatable cage or mesh, an ultrasonic ablation transducer, an electroporation electrode, a cryoablation element, or a virtual RF electrode.

[0095] In this manner, the ablation elements may be adapted and configured to deliver ablation energy circumferentially to create a circumferential lesion.

[0096] One aspect of the present disclosure is an ablation catheter for ablating greater splanchnic nerves, comprising an elongate shaft, a conductive flexible ablation element (optionally a distal coiled element and a proximal coiled element) carried on a distal portion of the elongate shaft, and a plurality of irrigation ports in the distal portion of the elongate shaft. The conductive flexible ablation element may have an axial length (e.g., from a proximal end to a distal end) of 5 to 25 mm.

[0097] In this aspect, the elongate shaft can be of a length such that at least a portion of the distal portion of the elongate shaft can be positioned within the T9, T10, or T11 intercostal vein. In this aspect, the conductive flexible ablation element can include a distal conductive flexible ablation element and a proximal conductive flexible ablation element (optionally coiled) carried on the distal portion of the elongate shaft.

[0098] In this aspect, a first subset of the plurality of irrigation ports may be disposed between windings of the conductive flexible ablation element (e.g., RF electrode), which may be the first electrode or the second electrode. Another subset of the plurality of irrigation ports may be distal to the conductive flexible ablation element. Another subset of the plurality of irrigation ports may be axially disposed between the distal and proximal ablation elements.

[0099] In this aspect, the elongate shaft may be free of irrigation ports between at least one winding at the distal and / or proximal ends of the conductive flexible ablation element, and optionally may be free of irrigation ports between at least one winding at the distal and / or proximal ends of the first and second coiled electrodes.

[0100] In this aspect, the conductive flexible ablation element may include a distal coiled electrode and a proximal coiled electrode, the distal and proximal ends of each of which may include a coil with a non-uniform pitch.

[0101] In this embodiment, the distal irrigation port may be within 2 mm of the distal end of the conductive flexible ablation element, which may be the distal end of the distal ablation element. In some cases, the number of distal irrigation ports may be 2 to 4 or more. The distal irrigation ports described herein may be axially aligned, as shown in the example of FIG. 8E.

[0102] In this embodiment, the distal conductive flexible ablation element and the proximal conductive flexible ablation element may be axially spaced apart by 2 mm or less (optionally 1.5 mm or less).

[0103] In this embodiment, the central irrigation ports between the distal and proximal ablation electrodes may include two to four or more ports and may be arranged axially as shown in the example of Figure 8E.

[0104] In this embodiment, the multiple irrigation ports may have a combined total area in the range of 1.51e-4 to 1.08e-3 square inches.

[0105] In this embodiment, the irrigation ports may all be in the range of 0.002" to 0.009" in diameter.

[0106] In this embodiment, the number of irrigation ports may range from 17 to 344.

[0107] In this aspect, the size and number of the multiple irrigation ports may be determined so that the Weber number is in the range of 0.4 to 53 when irrigation fluid is delivered from the multiple irrigation ports, optionally at a rate of 15 to 50 ml / min, and optionally with saline.

[0108] In this embodiment, the distal portion may have a distal length of 60-70 mm and may be sufficiently flexible to be advanced from the azygos vein into an intercostal vein. In this embodiment, the elongate shaft may have a central transition portion proximal to the distal portion, the central portion optionally having a central length of 15-25 mm and optionally a central stiffness greater than the distal stiffness of the distal portion. In this embodiment, the elongate shaft may have a proximal portion proximal to the central portion, the proximal portion optionally having a length greater than the distal length and a length greater than the central length, and the proximal portion optionally having a proximal stiffness greater than the central stiffness and a distal stiffness. In this embodiment, the central portion may be directly axially adjacent to the distal portion and proximal to the distal portion. In this embodiment, the proximal portion may be directly axially adjacent to the central portion and proximal to the central portion. In this embodiment, the distal portion may have a durometer hardness of 50-60D, optionally 55D. In this embodiment, the durometer of the central portion may be 60-70D, optionally 60-65D. In this embodiment, the distal end of the proximal portion may be 50 mm or more from the distal end of the catheter. In this embodiment, the proximal portion may be 75-100 mm from the distal end of the catheter, optionally extending to the proximal end of the elongate shaft. In this embodiment, the proximal portion may include a braided reinforcement structure, while the distal and central portions may optionally be free of a braided reinforcement structure. In this embodiment, the durometer of the proximal portion may be 70-80D, optionally 70-75D.

[0109] In this embodiment, the distal portion of the elongate shaft may have a straight or straight configuration (as shown in the example of Figure 8E) and may have an outer diameter of 1.5 to 3 mm when outside the sheath.

[0110] Any of the first and second ablation elements in this embodiment may have a coiled configuration as shown in the example of Figure 8E.

[0111] In this embodiment, the distal portion may include multiple irrigation ports having a helical configuration. There may be multiple sets of ports, each with a distinct helical configuration, as shown, for example, in the multiple irrigation port sets shown in the example of Figure 8E. These multiple sets may be located between the distal and proximal ends of any particular electrode, as shown in the example of Figure 8E.

[0112] In this embodiment, the distal portion of the shaft may have a distal diameter, the central portion may have a central diameter, and the proximal portion may have a proximal diameter, the distal diameter optionally being smaller than the central diameter, and the central diameter optionally being smaller than the proximal diameter. In this embodiment, the distal diameter may be 1.5-2.5 mm, optionally 2 mm. The central diameter may be 2.0-3.0 mm, optionally 2.5 mm. The proximal diameter may be 2.5-3.5 mm, optionally 3 mm.

[0113] One aspect of the present disclosure relates to tracking or calculating a volume of fluid delivered through a catheter into a patient. This aspect may include a computer-executable method adapted to calculate a cumulative volume of fluid delivered through a catheter into a patient, excluding (i.e., excluding) fluid that may have passed through the catheter but not been delivered into the patient's vasculature. The method may include initiating a method of calculating a cumulative volume of fluid delivered through the catheter into the patient from outside the catheter, and responding to an exclusion event indicating that the catheter is no longer inside the patient by stopping the method of calculating the cumulative fluid volume, thereby excluding the volume of fluid that was not delivered into the patient's vasculature.

[0114] In this aspect, an exclusion event may include a manual action that stops the method.

[0115] In this aspect, the exclusion event may include an automatic action that stops the method.

[0116] In this aspect, the method of calculating the cumulative liquid volume may include calculating the cumulative volume by multiplying the flow rate by the elapsed time. The flow rate may be determined by multiplying the volume per pulse by the number of pulses per second.

[0117] This aspect may also include calculating or tracking the cumulative volume of fluid not delivered into the patient's vasculature if the catheter is determined not to be within the patient's vasculature.

[0118] In this aspect, the exclusion event may optionally include, for example, a measured or calculated impedance value falling outside a range or exceeding an upper threshold. The exclusion event may include, for example, a measured or calculated impedance value greater than 700-900 Ω in monopolar mode. The exclusion event may include, for example, a measured or calculated impedance value greater than 300-600 Ω in bipolar mode. The exclusion event may include, for example, a measured or calculated impedance value outside 60-80 Ω.

[0119] In this aspect, the exclusion event may include determining whether the catheter is outside the body based on measured or calculated impedance. Initially, the catheter is outside the body, and the algorithm may be adapted to determine that the catheter has entered the body when a lower threshold is exceeded, with the pumped saline being included in the cumulative calculation. The algorithm may be adapted to determine that the catheter has left the body when an upper threshold is exceeded, with the pumped saline not being included in the cumulative calculation. The exclusion event may include a determination that the catheter is outside the body. If the catheter is outside the body, the exclusion event may include the measured impedance being higher than a lower threshold. If the catheter is inside the body, the exclusion event may include the measured impedance being higher than an upper threshold.

[0120] In this manner, the method of calculating cumulative liquid volume may continue uninterrupted unless an exclusion event occurs.

[0121] In this embodiment, the liquid may be saline.

[0122] Any of the methods in this aspect may be stored in an external energy delivery console of an ablation system, which may be any of the external systems described herein adapted to be in operative communication with any of the ablation catheters described herein.

[0123] One aspect of the present disclosure relates to a method of delivering ablation energy to tissue (e.g., tissue surrounding an intercostal vein), which may include delivering a waveform from any of the external systems described herein to any of the suitable ablation catheters described herein, and which may include the external system receiving information from any of the suitable ablation catheters described herein.

[0124] In this aspect, a method may include delivering ablative RF energy of a first waveform having an initial power of 15-50 W from a power module (e.g., part of an external system) to a first electrode; delivering ablative RF energy of a second waveform having an initial power of 15-50 W from the power module to a second electrode; receiving information indicative of at least one of a sensed temperature or a measured impedance; determining whether at least one of the sensed temperature or the measured impedance is above a limit; and reducing the power of at least one of the first waveform and the second waveform if at least one of the sensed temperature or the measured impedance is above a limit threshold.

[0125] The method of this aspect may be used with any suitable catheter described herein. For example, a first waveform may be delivered to a first electrode (optionally a coiled electrode) and a second waveform may be delivered to a second electrode (optionally a coiled electrode).

[0126] In this aspect, if at least one of the sensed temperature or the measured impedance is equal to or greater than the limit threshold and the minimum treatment time has not yet expired, the reducing step may include reducing the power of at least one of the first waveform and the second waveform to a second power that is less than the initial power. In this aspect, the second power may be 5-10 W less than any initial power.

[0127] In this aspect, if at least one of the sensed temperature or the measured impedance is equal to or greater than a limit threshold and the minimum treatment time has expired, the reducing step may include reducing the power of at least one of the first waveform and the second waveform to a second power of 0-1 W.

[0128] In this embodiment, the first and second waveforms may be multiplexed.

[0129] In this embodiment, the first and second waveforms may be asynchronous.

[0130] In this aspect, delivering from the power module to the first electrode may include delivering from the power module to the first electrode ablative RF energy of a first waveform having an initial power of 25 W. Delivering from the power module to the second electrode may include delivering from the power module to the second electrode ablative RF energy of a second waveform having an initial power of 25 W.

[0131] In this embodiment, the first and second waveforms may be alternating waveforms that alternate between ablative and non-ablative power amplitudes. The non-ablative power amplitude in this embodiment may be in the range of 0-1 W.

[0132] In this aspect, the determining step may include determining whether the sensed temperature is 40-95°C or greater (optionally 90°C or greater).

[0133] In this aspect, the receiving step may include receiving information from a temperature sensor associated with the first electrode (e.g., any of the coiled electrodes described herein). In this aspect, the receiving step may include receiving information from a second temperature sensor associated with the second electrode (e.g., any of the coiled electrodes described herein).

[0134] In this aspect, the determining step may include determining whether the measured impedance is greater than or equal to 200-500 Ω (optionally greater than or equal to 500 Ω).

[0135] In this aspect, reducing the power of at least one of the first waveform and the second waveform may include reducing the power of at least one of the first waveform and the second waveform to a power of 10 to 30 W (optionally 20 W).

[0136] In this aspect, reducing the power of at least one of the first waveform and the second waveform may include reducing the power of at least one of the first waveform and the second waveform by a power decrement of 1 to 30 W (optionally 5 to 10 W).

[0137] In this embodiment, the pulse width of at least one of the first and second waveforms may be in the range of 0.5 to 4 seconds.

[0138] In this aspect, the power of the first waveform may be reduced if the sensed temperature corresponding to the first electrode is above a limit, and the power of the second waveform may be reduced if the sensed temperature corresponding to the second electrode is above a limit.

[0139] In this embodiment, the delivering step may occur for at least 60 seconds.

[0140] In this aspect, the delivering step may be performed at a default setting that occurs over a period of 30 to 180 seconds.

[0141] Any method of this aspect may further include delivering irrigation fluid to the ablation catheter at a flow rate ranging from 10 to 30 ml / min. Delivering irrigation fluid to the ablation catheter may include delivering fluid to, through, and out of any of the ablation catheters described herein, including any description of an irrigation port that allows irrigation fluid to be delivered into a patient from that port.

[0142] One aspect of the present disclosure relates to an external device (which may include one or more individual components) adapted for use with any of the ablation catheters described herein. External device, as used herein, primarily refers to one or more components of a system that remain external to the patient (e.g., a power module, an energy generator, etc.). The external devices described herein may be adapted to be coupled to or associated with any of the ablation catheters described herein so as to be in operative communication with the ablation catheter. The external devices described herein may be referred to as an external system, which is understood to refer to the external nature of one or more components. The ablation catheter and one or more external components may be collectively referred to herein as a system. Any of the features of this aspect may be incorporated into previously described aspects related to delivering ablation energy, and vice versa. For example, any of the methods described in previously described aspects may be stored in one or more memories of any of the external devices in this aspect of the present disclosure and used with any of the ablation catheters in this aspect.

[0143] This aspect may include an external device or system adapted for use with an ablation catheter including first and second ablation electrodes. The external device may include a power output module adapted to deliver ablative RF energy of a first waveform having an initial power of 15 to 50 W and ablative RF energy of a second waveform having an initial power of 15 to 50 W. The external device may also include a module adapted to receive information indicative of at least one of a sensed temperature or a measured impedance, determine whether at least one of the sensed temperature or the measured impedance is above a limit, and cause the power output module to reduce the power of at least one of the first waveform and the second waveform if at least one of the sensed temperature or the measured impedance is above a limit threshold.

[0144] In this aspect, the module may include at least one of a limit temperature module or a limit impedance module.

[0145] One aspect of the present disclosure relates to delivering irrigation fluid to an ablation catheter, which may include a method of delivering ablation energy and irrigation fluid to a catheter for ablating a greater splanchnic nerve, the method comprising: positioning an ablation catheter within an intercostal vein, delivering ablation energy to one or more ablation elements carried on a distal portion of the ablation catheter, ablating the greater splanchnic nerve outside the intercostal vein, and delivering irrigation fluid from a plurality of irrigation ports to the distal portion of the ablation catheter at a rate of 15-50 ml / min.

[0146] Any feature of this aspect of the present disclosure may be included or incorporated in any one or more steps of any other aspect, including aspects related to delivering ablation energy using any of the ablation catheters described herein.

[0147] In this aspect, delivering irrigation fluid may include delivering irrigation fluid from a plurality of irrigation ports to the distal portion of the ablation catheter at a rate of 30 ml / min.

[0148] In this aspect, delivering irrigation fluid may include delivering irrigation fluid to the distal portion of the catheter from between 17 and 344 irrigation ports.

[0149] In this aspect, delivering irrigation fluid includes delivering irrigation fluid from a plurality of distal irrigation ports disposed distal to the one or more ablation elements.

[0150] In this aspect, delivering irrigation fluid may include delivering irrigation fluid from a plurality of central irrigation ports positioned between the proximal and distal ablation elements.

[0151] In this aspect, the step of delivering irrigation fluid may include a step of not delivering irrigation fluid from any portion of the distal portion of the shaft proximal to the one or more ablation elements, optionally by not providing an irrigation port proximal to the one or more ablation elements.

[0152] In this aspect, delivering ablation energy may include delivering energy at a power of 15-50 W (optionally 35 W).

[0153] In this aspect, delivering irrigation fluid may include delivering irrigation fluid distal to the one or more ablation elements and not delivering irrigation fluid proximal to the one or more ablation elements.

[0154] In this aspect, delivering irrigation fluid may include delivering irrigation fluid from a plurality of irrigation ports, the plurality of irrigation ports optionally having a combined area in the range of 1.51e-4 to 1.08e-3 square inches.

[0155] In this embodiment, the diameter of the irrigation ports may range from 0.002 to 0.009 inches.

[0156] In this aspect, delivering irrigation fluid from multiple irrigation ports at a rate of 15-50 ml / min may result in a Weber number in the range of 0.4-53.

[0157] In this aspect, delivering ablation energy may include delivering ablation energy to first and second coiled ablation elements axially spaced apart on the shaft.

[0158] In this aspect, delivering irrigation fluid may include delivering irrigation fluid from at least some of a plurality of ports disposed between the windings of the first and second coiled ablation elements.

[0159] The drawings included herein are intended to illustrate various embodiments of the articles, methods, and apparatus herein and are not intended to limit the scope of the teachings in any way. [Brief explanation of the drawings]

[0160] [Figure 1] FIG. 1 is a schematic isometric view of an ablation catheter placed in an intercostal vein for ablation of thoracic splanchnic nerves. [Figure 2] FIG. 1 is a schematic cross-sectional view of an ablation catheter positioned within an intercostal vein and a centrally located azygos vein. [Figure 3] FIG. 1 is a schematic cross-sectional view of the anatomy showing a right-biased azygos vein. [Figure 4] FIG. 1 is a schematic cross-sectional view of the anatomy showing a left-biased azygos vein. [Figure 5] FIG. 1 is a schematic cross-sectional view of the anatomy showing the range of azygos vein locations and the range of right GSN locations. [Figure 6] This is an AP fluoroscopic image of the patient's T8-T12 chest region. [Figure 7] This is a RAO30 fluoroscopic image of the patient's T8-T12 chest region. [Figure 8A] FIG. 1 is a schematic diagram of an ablation catheter having two coiled RF electrodes. [Figure 8B] FIG. 1 is a schematic diagram of an ablation catheter having two coiled RF electrodes and a distal deployable element. [Figure 8C] 1 is a schematic diagram of first, second, and third sections of a catheter shaft. [Figure 8D] 1 is a schematic diagram of a distal portion of an ablation catheter, the distal portion including irrigation holes arranged in a spiral pattern between the windings of a helical electrode and irrigation holes distal to the distal electrode. [Figure 8E] 1 is a schematic diagram of a distal portion of an ablation catheter, the distal portion including irrigation holes arranged in a spiral pattern between at least some windings of a helical electrode, and a plurality of irrigation holes distal to the distal electrode and between the proximal and distal electrodes. [Figure 9] FIG. 1 is a schematic diagram of an ablation catheter having two coiled RF electrodes and a distal and proximal deployable element. [Figure 10] FIG. 1 is a schematic diagram of an ablation catheter having two coiled RF electrodes and a distal, proximal, and intermediate deployable elements. [Figure 11] FIG. 1 is a schematic diagram of an ablation catheter having an RF electrode with expandable wire struts. [Figure 12] 1 is a schematic diagram of an ablation catheter with RF electrodes that includes an inflatable balloon with RF electrodes on its surface. [Figure 13A] ~ [Figure 13B] FIG. 1 is a schematic diagram of an ablation catheter having an RF electrode comprising an inflatable balloon having an RF electrode thereon made from conductive ink. [Figure 14] FIG. 1 is a schematic diagram of an ablation catheter with RF electrodes that includes an inflatable balloon with a zigzag pattern of RF electrodes on its surface. [Figure 15] 1 is a schematic diagram of an ablation catheter having an RF electrode within a cavity defined by a membrane. [Figure 16] FIG. 1 is a schematic diagram of an ablation catheter having multiple RF electrode sections on a tapered shaft. [Figure 17A] ~ [Figure 17B] FIG. 1 is a schematic diagram of an ablation catheter having RF electrode pads on an inflatable balloon. [Figure 18] 1 is a schematic diagram of an ablation catheter having an ultrasound transducer. [Figure 19] The image includes plots of RF power delivered to the first electrode and the second electrode, temperature monitored by sensors associated with the first and second electrodes, and bioelectrical impedance monitored from the first and second electrodes on the same time axis. [Figure 20] FIG. 10 is an exemplary machine state diagram for an exemplary saline tracking algorithm. [Figure 21A] FIG. 1 is a schematic diagram of an ablation catheter with a flat spiral electrode. [Figure 21B] FIG. 1 is a schematic diagram of an ablation catheter with a flat spiral electrode. DETAILED DESCRIPTION OF THE INVENTION

[0161] Disclosed herein generally relates to methods for treating heart failure and / or hypertension by increasing splanchnic capacitance. Some approaches include systems, devices, and methods for transvascular (e.g., transvenous) ablation of target tissue to increase splanchnic venous capacitance or venous compliance. The devices and methods, in some embodiments, may be used to ablate splanchnic nerves to increase splanchnic capacitance. For example, the devices disclosed herein may be endovascularly navigated to one or more target vessels in the region of the thoracic splanchnic nerves ("TSN") (e.g., the preganglionic greater splanchnic nerve ("GSN"), the lesser splanchnic nerve, or the least splanchnic nerve, or one of their roots (the TSN nerve root)). The target vessel may be, for example, an intercostal vein or azygos vein (or both), or one of the veins of the azygos venous system, preferably one or more of the three lowest (i.e., most caudal) intercostal veins (which may be T9, T10, or T11).

[0162] FIG. 1 illustrates a patient's thoracic spine, including the T12 (62), T11 (63), T10 (64), and T9 (65) vertebrae, intervertebral discs, sympathetic trunk 54, azygos vein 50, right T11 intercostal vein 55, right T10 intercostal vein 56, right T9 intercostal vein 66, GSN root 53, and fully formed GSN 52. The lesser and least splanchnic nerves and their roots have been omitted for simplicity. The primary goal of the proposed procedure is to ablate the GSN or its roots, which will be discussed in detail herein. However, ablation of the lesser or least splanchnic nerves or their roots may also have therapeutic effects and may be the goal of the procedure. In the illustration, a delivery sheath 80 is positioned within the azygos vein, and an ablation catheter 81 is delivered through the sheath and passes from the azygos vein into the T11 intercostal vein. The sympathetic trunk runs roughly parallel to the spine, consistently passing near each costovertebral joint 61 (see Figure 2). The GSN roots branch off from the sympathetic trunk on the right side of the body, typically at the T9 vertebra, and converge to form the GSN, which extends at an angle from the sympathetic trunk toward the anterior center of the spine, anterior to the intercostal veins between the intercostal veins and the parietal pleura 60 (see Figure 2). The azygos vein 50 runs along the anterior portion of the spine and can be said to run somewhat straight and parallel to the axis of the spine, as shown in Figure 1. However, the exact location of the azygos vein relative to the spine varies from patient to patient and is located at various vertebral levels. At the T9, T10, and T11 vertebral levels, the azygos vein 50 may be centered relative to the midline of the vertebra 69, as shown in FIG. 2, or may be offset to the right 50R relative to the midline of the vertebra 69, as shown in FIG. 3, or may be offset to the left 50L relative to the midline of the vertebra 69, as shown in FIG. 4. Cadaveric analysis conducted by the authors indicates that the location of the azygos vein relative to the center of the spine at the T9, T10, and T11 levels falls within a range of 10 mm to the left or right of the center for the majority of people. FIG. 5 illustrates the left-offset azygos vein 50L, the right-offset azygos vein 50R, and the centrally located azygos vein 50C, along with the extent 67 of the azygos vein relative to the center of the vertebra 69.Furthermore, the exact location of the right GSN from patient to patient varies somewhat, including where it originates from the sympathetic trunk, the angle at which it extends, and its orientation relative to the spine. Therefore, there may be variability in the location of the GSN relative to the T9, T10, and T11 vertebrae. Based on a cadaveric analysis conducted by the authors, the location of the right GSN relative to the spinal center at the T9, T10, and T11 levels ranges from 0 to 25 mm to the right of the center 69, as shown in the range box 68 in Figure 5.

[0163] One endovascular approach for transvascular ablation of TSNs (particularly GSNs) involves accessing the patient's venous vasculature in the jugular or femoral vein with an access introducer sheath (e.g., 12F), delivering a delivery sheath (e.g., 9F sheath) to the azygos vein (e.g., one or two chest levels above the target intercostal vein), optionally delivering contrast through the sheath to fluoroscopically display the location of the vein, and optionally delivering a guidewire (e.g., 0.014" guidewire) through the delivery sheath to the targeted T9, T10, or T11 intercostal vein. The method may include one or more of the following steps: reaching the ablation catheter; delivering the ablation catheter through a delivery sheath to the azygos vein; placing the ablation element within the intercostal vein, the azygos vein, or both, optionally via a guidewire; and aligning radiopaque markers on the ablation catheter with (positioning relative to) anatomical landmarks to position the ablation element in an area that maximizes the effectiveness of ablation of the target TSN / GSN while minimizing the risk of injuring one or more non-target structures.

[0164] Several important anatomical structures near this area that must not be injured include the sympathetic trunk 54, vagus nerve, thoracic duct, and esophagus. Therefore, to ensure safety, the ablation zone must be contained within a safe area that will not injure such structures. Due to variations in the location of the azygos vein and GSN relative to the T9, T10, and T11 vertebrae, there is also variation in the location of the GSN relative to the intercostal or azygos vein within which the ablation element is placed.

[0165] Bone, blood vessels injected with radiopaque contrast agents, and medical devices made from radiopaque materials are visible under fluoroscopy, but nerves are not. To ensure the safety and effectiveness of ablation of the TSN (e.g., GSN), an ablation device designed for transvascular (e.g., transvenous) ablation of the TSN (e.g., GSN) via the intercostal veins, the azygos vein, or both may be provided during a procedure. The procedure may include fluoroscopic imaging to position the ablation elements of the ablation catheter relative to the bony or vascular structures.

[0166] In a first embodiment of a method for ablating the right GSN, an ablation catheter having a proximal radiopaque marker 136, a distal radiopaque marker 130, an ablation element 131 or multiple ablation elements 132, 133, and an optional gap 135 between the ablation element and the distal radiopaque marker is advanced from the azygos vein 50 into an intercostal vein 55 at one of the three lower thoracic levels (e.g., T9, T10, T11). The C-arm is positioned in an anterior-posterior (AP) orientation. The proximal radiopaque marker 136 is aligned with the midline of the vertebrae 69. This is possible if the azygos vein 50 is centered or deviated to the left. If the azygos vein 50 is deviated to the left, the proximal radiopaque marker must be advanced into the intercostal vein to align it with the midline of the vertebrae 69. If the azygos vein is deviated to the right, the proximal radiopaque marker 136 cannot be placed at the midline of the vertebra 69. In this case, the proximal radiopaque marker 136 may be placed at the ostium of the intercostal vein, which is on the right side of the vertebra 69. Optionally, the position of the distal radiopaque marker 130 relative to the costovertebral joint (e.g., with the C-arm in the RAO orientation) can be assessed to ensure there is no risk of injury to the sympathetic trunk (e.g., if the patient is very small and the azygos vein is deviated too far to the right). The C-arm may be angled obliquely to the right (in the RAO orientation) to maximize the 2D projection of the cross section of the intercostal vein between the costovertebral joint 61 and the anterior midline of the vertebra 69 ( FIG. 7 ). For example, the C-arm may be positioned at a right anterior oblique (RAO) angle ranging from 20 to 70° from the AP (e.g., in the range of 30 to 60°, in the range of 35 to 55°, at approximately 30°, or at an angle that maximizes the projection distance between the proximal and distal RO markers). With this in mind, the user may check that the distal radiopaque marker is not positioned too close to the costovertebral joint 61. For example, if the distal radiopaque marker is positioned just distal to the ablation element, a distance of at least 3 mm (e.g., at least 5 mm) may be selected to avoid injuring the sympathetic nerve trunk.In another example, if the distal radiopaque marker is located distal to the ablation element with a known spacing between them, the distal radiopaque marker may be aligned with or proximal to the costovertebral joint to ensure safety of the sympathetic joint. If the distal radiopaque marker is too close to or beyond the costovertebral joint, the catheter may be pulled back until the distance between the distal radiopaque marker and the costovertebral joint is deemed acceptable, allowing the proximal radiopaque marker to be positioned within the azygos vein (especially if the azygos vein is deviated to the right). If the ablation element consists of multiple (e.g., two) ablation elements, ablation may be performed first with the more proximal ablation element, after which the catheter may be pulled back to properly position the distal radiopaque marker relative to the costovertebral joint. Subsequent ablations may then be performed with the more distal ablation elements.

[0167] In a second embodiment of a method for ablating the right GSN, an ablation catheter having a proximal radiopaque marker 136, a distal radiopaque marker 130, one ablation element 131 or multiple ablation elements 132, 133, and an optional gap 135 between the ablation element and the distal radiopaque marker is advanced from the azygos vein 50 into an intercostal vein 55 at one of three lower chest levels (e.g., T9, T10, T11). The C-arm is positioned in an anterior-posterior (AP) orientation. The proximal radiopaque marker 136 is aligned with an intercostal vein ostium 59. The intercostal vein ostium can be found, for example, by injecting contrast to visualize the vasculature fluoroscopically, or, if a guidewire has been previously placed in the target intercostal vein, the location of the intercostal vein ostium can be determined from the bend in the guidewire or ablation catheter. If the azygos vein is deviated to the left, the catheter is advanced distal to the intercostal vein ostium until the proximal radiopaque marker 136 is aligned with the midline of the vertebra 69. With this placement strategy, the proximal radiopaque marker 136 will be aligned with the midline of the vertebra 69 if the azygos vein is deviated to the left or centered, and will be aligned to the right of the vertebral midline if the azygos vein is deviated to the right. At the same time, the proximal radiopaque marker 136 will be aligned with the intercostal vein ostium if the azygos vein is deviated to the right or centered, and will be aligned with the midline of the vertebra 69 if the azygos vein is deviated to the left. Optionally, the position of the distal radiopaque marker 130 relative to the costovertebral joint can be assessed (e.g., with the C-arm in the RAO orientation) to ensure there is no risk of injury to the sympathetic trunk (e.g., if the patient is very small and the azygos vein is extremely deviated to the right). The C-arm may be angled obliquely to the right (RAO direction) to maximize the 2D projection of the cross section of the intercostal veins between the costovertebral joint 61 and the anterior midline of the vertebrae 69 (Fig. 7).For example, the C-arm may be positioned at a right anterior oblique (RAO) angle ranging from 20 to 70° from the AP (e.g., ranging from 30 to 60°, ranging from 35 to 55°, or approximately 30°, at an angle that maximizes the projection distance between the proximal and distal RO markers). With this in mind, the user may check to ensure that the distal radiopaque marker is not positioned too close to the costovertebral joint 61. For example, if the distal radiopaque marker is positioned just distal to the ablation element, a distance of at least 3 mm (e.g., at least 5 mm) may be selected to avoid injury to the sympathetic trunk. In another example, if the distal radiopaque marker is positioned distal to the ablation element with a known spacing between them, the distal radiopaque marker may be aligned with or proximal to the costovertebral joint to ensure safety of the sympathetic joint. If the distal radiopaque marker is too close to or beyond the costovertebral joint, the catheter may be pulled back until the distance between the distal radiopaque marker and the costovertebral joint is deemed acceptable, allowing the proximal radiopaque marker to be placed within the azygos vein (especially if the azygos vein is deviated to the right).

[0168] In a third embodiment of a method for ablating the right GSN, an ablation catheter having a distal radiopaque marker 130, one or more ablation elements 131, 133, and a gap 135 between the ablation element and the distal radiopaque marker is advanced from the azygos vein 50 into an intercostal vein 55 at one of three lower thoracic levels (e.g., T9, T10, T11). The C-arm is angled obliquely to the right side to maximize the 2D projection of the cross section of the intercostal vein between the costovertebral joint 61 and the anterior midline of the vertebra 69 (FIG. 2). For example, the C-arm may be positioned at a right anterior oblique (RAO) angle ranging from 20 to 70° from the AP (e.g., in the range of 30 to 60°, in the range of 35 to 55°, at approximately 30°, or at an angle that maximizes the projection distance between the proximal and distal RO markers). A fluoroscopic image in an anterior-posterior (AP) view is shown in FIG. 6 . For comparison, a fluoroscopic image at 30° RAO is shown in FIG. 7 . The catheter is advanced so that the distal radiopaque marker 130 is aligned with the costovertebral joint 61. Because the sympathetic trunk 54 is adjacent to the costovertebral joint 61, a gap between the distal radiopaque marker and the ablation element prevents injury to the sympathetic trunk. This gap may, for example, be in the range of 0-25 mm in length (e.g., 3-25 mm, 5-25 mm, 5-20 mm). Optionally, an inflatable balloon 134 may be positioned on the catheter shaft within the gap, which may help to anchor the catheter or dam the ablation energy proximal to the balloon. Optionally, the catheter shaft 138 distal to the ablation element may be narrower or more flexible than the remainder of the shaft to facilitate delivery through the narrowed distal portion of the intercostal vein. Optionally, the ablation element is long enough to ablate up to the anterior midline of vertebra 69 when the distal radiopaque marker is aligned with the costovertebral joint. For example, the ablation element can have a total length in the range of 5-25 mm (e.g., 10-25 mm, 15-20 mm).The ablation catheter may have a proximal radiopaque marker positioned just proximal to the ablation element. Optionally, the user may image the proximal radiopaque marker to confirm its location at the anterior midline of the vertebra 69 before delivering ablation energy. If the proximal radiopaque marker is to the left of the midline 69, there may be a risk of injuring non-target tissue, such as the thoracic duct or esophagus, for example, in very small patients. To mitigate this risk, a catheter with reduced ablation element size may be used, or, if the ablation element is comprised of multiple ablation elements, only the elements between the midline 69 and the distal radiopaque marker may be activated for ablation. Conversely, if the proximal radiopaque marker is to the right of the midline 69, there may be a risk of missing the GSN, for example, in very large patients. To mitigate this risk, another ablation may be performed at another intercostal level, or another ablation may be performed within the same intercostal vein with the ablation element retracted until the proximal radiopaque marker is aligned with the midline 69.

[0169] In a fourth embodiment of a method for ablating the right GSN, an ablation catheter having ablation elements 131 is advanced from the azygos vein into an intercostal vein at one of the three lower thoracic levels (e.g., T9, T10, T11). The ablation catheter may include multiple ablation elements, distal radiopaque markers disposed at the distal ends of the ablation elements, and proximal radiopaque markers disposed at the proximal ends of the ablation elements. To maximize the 2D projection of the cross-section of the intercostal vein between the costovertebral joint 61 and the anterior midline of the vertebra 69, the C-arm is angled obliquely to the right side ( FIG. 5 ). For example, the C-arm may be positioned at a right anterior oblique (RAO) angle ranging from 25 to 65° from the AP (e.g., ranging from 30 to 60°, from 35 to 55°, or approximately 30°). The catheter is advanced so that the distal radiopaque marker is aligned with the relative position of the costovertebral joint and the opposite edge of the vertebral body in the oblique view. For example, the distal radiopaque marker may be aligned with a point midway between the costovertebral joint and the opposite edge of the vertebral body in the oblique view. The total length of the ablation element may be expected to cover the GSN location range 68 in most patients. As with the previous method, the proximal end of the ablation element may be at or to the left of the anterior midline of the vertebra 69 in situations where the azygos vein is centrally located or deviated to the left, or within the azygos vein in situations where the azygos vein is deviated to the right. Ablation energy may be delivered from the ablation element to ablate the range without moving the catheter. Optionally, the catheter may be moved to another intercostal level, and a second ablation may be created using the same method steps.

[0170] By implementing any of the exemplary embodiments of the placement strategies disclosed herein, it is expected that a total length of the ablation element 131 of less than 30 mm (e.g., less than 25 mm, less than 20 mm, or approximately 15 mm) will avoid injury to the sympathetic trunk in the majority of patients, even if the azygos vein is deviated to the right. Furthermore, when implementing the methods described herein, it is expected that a total length of the ablation element 131 of 15 mm or greater will ablate the GSN in the majority of patients. Therefore, a total length of the ablation element 131 in the range of 15 to 30 mm can be effective and safe for the majority of patients using these placement strategies. However, shorter total lengths of the ablation element may be appropriate for exceptional patients. For example, the ablation element may have a total length in the range of 5 to 25 mm (e.g., in the range of 10 to 20 mm, or in the range of 10 to 15 mm).

[0171] As used herein, an ablation element may refer to a single structure or multiple structures. For example, as used herein, an ablation element may include multiple axially spaced ablation electrodes, each of which may be adapted to facilitate delivery of ablation energy.

[0172] Once acceptable ablation element placement is achieved, ablation energy can be delivered from the one or more ablation elements without the need to move the catheter, for example, using any of the exemplary embodiments of the placement strategies described herein. By delivering ablation energy from the ablation elements, tissue surrounding the intercostal vein can be ablated circumferentially to a depth ranging from 2 to 10 mm (e.g., ranging from 2 to 8 mm, ranging from 3 to 8 mm, approximately 5 mm). Optionally, this procedure can be repeated at another thoracic level (e.g., a more cranial level, a more caudal level, another of the T9, T10, or T11 intercostal veins on the same side of the patient), particularly if the azygos vein is deviated to the right. As an alternative or addition to having distal and proximal radiopaque markers on either end of one or more ablation elements, the ablation elements themselves may be radiopaque, and the same methods described herein may be used to position the distal and proximal ends of the ablation elements relative to anatomical landmarks (e.g., the spinal midline, the costovertebral joint, etc.). Thus, as used herein, the term radiopaque marker may refer to the ablation elements if they are radiopaque. In some alternative embodiments, the radiopaque marker may include a relatively long radiopaque marker positioned below or next to one or more ablation elements, the proximal end of which is at least aligned with or extends up to 3 mm proximal to the ablation element, and the distal end of which is at least aligned with or extends up to 3 mm distal to the ablation element.

[0173] In any of the exemplary embodiments of the placement strategies disclosed thus far, situations may arise in which a portion of an ablation element is within the azygos vein and another portion is within an intercostal vein, specifically, when the total length of one or more ablation elements of an ablation catheter ranges from 10 to 25 mm. The azygos vein is larger and carries more blood than the intercostal veins. This may affect whether effective ablation can be created around the azygos vein and even within the intercostal veins, and may require different energy delivery parameters than ablation completed within the intercostal vein. To address this, an ablation catheter may have multiple ablation elements, with at least one ablation element located entirely within the intercostal vein and the remaining ablation elements within the intercostal vein, the azygos vein, or both. Different ablation energy delivery parameters may be used for different scenarios, for example, greater power or energy may be delivered to ablation elements within the azygos vein, or ablation energy may be delivered only to elements that are entirely or partially within the intercostal vein. The locations of the multiple ablation elements can be identified by fluoroscopic imaging or by monitoring the electrical impedance between each ablation element (eg, an RF electrode) and a dispersive electrode.

[0174] Optionally, two or even three levels may be ablated, particularly if the azygos vein is right-biased, but may also be performed if the azygos vein is centrally located or left-biased, which may further increase efficacy.

[0175] Alternative devices and methods of use may include shorter ablation elements, which are used to create relatively short ablations, with multiple repositioning to create multiple ablations within GSN location range 68. If the azygos vein is centrally located or deviated to the left, all ablations may be created within intercostal veins 55 to cover range 68. If the azygos vein is deviated to the right, ablations may be performed within the intercostal veins to cover a portion of range 68, followed by ablation at another intercostal level to increase the probability of ablation of the GSN. Optionally, ablations may be created from the azygos vein, which may use different energy delivery parameters (e.g., greater energy or power).

[0176] Ablation catheters adapted to ablate TSNs (e.g., GSNs) from the intercostal and / or azygos veins (e.g., using one or more of the embodiments of the placement strategies disclosed herein) may have features that enable the catheter to be delivered intravascularly to a desired location within the T9, T10, or T11 intercostal vein, and to be positioned relative to anatomical features to effectively ablate the target TSN while safely avoiding important non-target structures in the majority of patients, and to deliver ablation energy capable of ablating the target TSN. The features of the ablation catheter and system can enable a user to relatively easily and efficiently ablate the TSN without sacrificing efficacy or safety. For example, once the ablation element of the catheter is positioned (e.g., using the methods disclosed herein), ablation energy can be delivered from a computerized ablation console, which may be done by pressing a button or with at least minimal adjustment, repositioning, dragging, or torqueing of the catheter, or with minimal user decision-making regarding energy delivery. Despite the variability in the location of the GSN 68 and the azygos vein 67 (see FIG. 5), the features of the ablation catheters and systems disclosed herein can allow the TSN / GSN to be ablated with one placement and energy delivery procedure, or in some cases with additional placement (e.g., additional placement in another of the T9, T10, or T11 intercostal veins) and energy delivery, increasing the probability of success in the majority of patients.

[0177] An ablation catheter for transvascular ablation of a GSN may have a proximal end, a distal end, an elongate shaft therebetween, a distal portion (e.g., including the most distal 7 cm), and an ablation element on, at, or carried by the distal portion. The ablation element may be adapted (including sized and / or configured) to create an ablation having a length ranging from 5 to 25 mm, preferably 10 to 25 mm (e.g., 15 to 20 mm), and a radial depth of at least 5 mm from the vessel surface. A handle may be located at the proximal end of the catheter to accommodate electrical or fluid connections or to facilitate handling of the catheter. The elongate shaft from the strain relief region to the distal tip may be 100-140 cm in length (e.g., 110-130 cm, e.g., about 120 cm), which allows the distal portion to be delivered from an arteriotomy site, such as a femoral venous access (or other access location, e.g., a jugular, brachial, radial, hepatic, or subclavian vein), to the T11 intercostal vein in most human patients; alternatively, the elongate shaft may be 50-140 cm in length, which allows the distal portion to be delivered from a jugular venous access to the T11 intercostal vein in most patients. To be deliverable through a 9F delivery sheath, the catheter may have a maximum outer diameter of 3 mm (e.g., 2.5 mm, 2 mm, 1.5 mm), at least in its delivery state. In some embodiments, the catheter may optionally have a deployable structure that expands beyond this dimension once advanced through the delivery sheath and positioned within the target vessel. An ablation catheter for delivering an ablation element to an intercostal vein (e.g., a T9, T10, or T11 intercostal vein) via an endovascular approach, including an azygos vein approach to the intercostal vein, may have a shaft that facilitates guidewire tracking, pushability, transmission of translational forces from the catheter handle, and kinking-free passage through sharp bends from the azygos vein to the intercostal vein. As shown in FIG. 8C , the catheter shaft may include a first section 340, a second section 341, and a third section 342.The first section 340 may be more flexible than the second and third sections and may carry ablation elements such as the two coiled electrodes 133 and 132 shown. This first section may be flexible enough to navigate the sharp bends (e.g., radius of curvature ≧5 mm, angle up to 120 degrees) from the azygos vein to the intercostal veins. The first section may be in the range of 60-100 mm in length (e.g., approximately 65 mm) and may be made from a single piece of Pebax® tubing with a durometer of 50-60D (e.g., 55D).

[0178] The second section 341 may be intermediate in flexibility between the first and third sections and may act as a kink-resistant transition region and strain relief region. For example, the second section may be made from a single piece of Pebax® tubing having a length in the range of 15-25 mm (e.g., 20 mm) and a durometer hardness of 60-70D (e.g., 60-65D, e.g., 63D).

[0179] The third section 342 may be at least a portion of the proximal portion of the elongate shaft and may be adapted for pushability, kink resistance, torque transmission, and flexibility. For example, the third section of the elongate shaft may extend from the proximal end of the catheter to approximately 85 mm from the distal end (e.g., in the range of 75-100 mm), and may optionally include a metal wire braid embedded in the outer layer of the shaft. An example material for the third section of the elongate shaft may be extruded Pebax® with a durometer of 70-75D, e.g., 72D. For example, the first section 340 may be more flexible than the second section 341, which may be more flexible than the third section 342, and flexibility may be enhanced by using a lower durometer material, or a more flexible braided or non-braided outer layer. The maximum outer diameter of the elongate shaft, at least in the delivery state, can be in the range of 1.5 to 3 mm. Optionally, as shown in FIG. 8C , a first section 340 of the shaft can be made from a smaller diameter tubing than a second section 341, which can be smaller in diameter than a third section 342 of the shaft. For example, the first section can be made from a tubing with an outer diameter of 2 mm, the second section can be made from a tubing with an outer diameter of 2.5 mm, and the third section can be made from a tubing with an outer diameter of 3 mm. Optionally, the elongate shaft can have a tapered, soft distal tip 345, which can be in the range of 5 to 30 mm in length (e.g., approximately 8 mm) and softer than the first section. Optionally, the first, second, or third section of the shaft can have a lubricious coating applied to its outer surface to further improve delivery through the vasculature. A guidewire lumen may run through the elongate shaft with an exit port 82 at the distal tip of the shaft. The guidewire lumen may be made, for example, from polyimide tubing with an inner diameter of 0.014 inches and disposed within the lumen of the shaft.

[0180] The ablation catheter may have an ablation element adapted to deliver ablation energy to a target nerve up to 5 mm from the vessel surface when the total length is in the range of 10-25 mm (e.g., 10-20 mm, e.g., 15-20 mm). The ablation element may consist of multiple (e.g., two) ablation elements located in a region of the shaft having a total length of 10-25 mm (e.g., 10-20 mm, e.g., 15-20 mm), even if the ablation elements are axially spaced apart. The ablation element may include one or more of RF ablation electrodes, coiled wire electrodes, laser-cut RF electrodes, RF electrodes printed with conductive ink, RF electrodes on an inflatable balloon (e.g., made with conductive ink or flexible circuit), conductive membrane RF electrodes, RF electrodes on an inflatable cage or mesh, ultrasound ablation transducers, electroporation electrodes, cryoablation elements, or virtual RF electrodes.

[0181] The ablation element may be adapted to deliver ablation energy circumferentially, i.e., radially symmetrically, around the ablation element and the vessel within which it is located. While GSNs necessarily pass anterior to the intercostal and azygos veins, it is safe and feasible to ablate tissue surrounding the intercostal or azygos veins, and ablation in a circumferential direction may allow for a simpler and faster procedure because it does not require targeting of energy delivery, which tends to reduce user error. Features that may enable circumferential ablation may include, but are not limited to, ablation electrodes that expand to uniformly contact the vessel wall around the circumference of the vessel, ablation electrodes used with conductive fluids, electrically insulating balloons or expandable structures that contain the ablation energy to a segment of the target vessel and allow the ablation energy to be directed radially, and ablation elements (e.g., cylindrical ultrasound transducers) that direct ablation energy circumferentially.

[0182] In some embodiments, the ablation element is an RF electrode, and saline may be delivered to a blood vessel in fluid communication with the RF electrode. An irrigation lumen in communication with an irrigation port may be located distal to the ablation element, or beneath the ablation element (in some designs that allow irrigated saline to pass through the ablation element), or in some embodiments within the deployable structure. The irrigation lumen may be, for example, a lumen in the elongate shaft in fluid communication with tubing at the proximal end of the catheter that is connectable to a fluid source and pump.

[0183] Optionally, at least one deployable occlusion structure (e.g., a balloon, bellows, wire mesh, wire braid, coated wire mesh, or coated wire braid) may be located on the shaft distal to the ablation element. The deployable structure may function to secure the catheter in place during energy delivery and, in some cases, to enhance safety by avoiding ablation of the sympathetic nerve trunk by providing electrical insulation or by containing saline proximal to the deployable structure. Optionally, a deployable occlusion structure may be located just proximal to the proximal end of the ablation element and may function to divert blood flow in the azygos vein away from the ablation zone. For example, the deployable occlusion structure may be a balloon, e.g., a urethane balloon having a length (axially of the shaft) of approximately 2.5 mm and an inflated diameter of approximately 2.5-7 mm (e.g., 3-6 mm, 4-5 mm). The balloon may be in fluid communication with an inflation port that connects the balloon to an inflation lumen, which is connectable to an inflation source at the proximal end of the catheter. Optionally, the inflation lumen may be in fluid communication with an irrigation lumen, which is connectable to a lumen source and a pump. Optionally, the balloon of such a catheter may have holes that allow irrigation fluid to flow out of the inflated balloon and toward the ablation element.

[0184] The ablation catheter may have a proximal radiopaque marker located on the shaft at or proximal to the proximal end of the ablation element. Optionally, the ablation catheter may include a distal radiopaque marker located on or distal to the distal end of the ablation element. Optionally, there may be a space between the distal radiopaque marker and the distal end of the ablation element, the space being in the range of 0.1 to 25 mm in length (e.g., 0.1 to 5 mm, e.g., 0.1 to 3 mm, e.g., 0.5 mm, 1 mm, or 1.5 mm). For example, as shown in FIG. 2, the distal radiopaque marker 130 may be aligned with or positioned relative to an anatomical landmark such as the costovertebral joint 61, with a space 135 (e.g., 1 to 25 mm) between the distal radiopaque marker 130 and the distal end of the ablation element 132 to position the ablation element at a safe distance from the sympathetic nerve trunk 54. Optionally, an expandable structure 134 may be disposed in the space capable of transitioning between a contracted state (outer diameter equal to the outer diameter of the shaft, e.g., in the range of 1.5-3 mm) and an expanded state (expanded outer diameter to the range of 3-7 mm). The expandable structure may be a balloon, a bellows, a wire mesh, a wire braid, a coated wire mesh, or a coated wire braid.

[0185] An example of an ablation catheter sized and adapted for GSN ablation is shown in Figure 2. Ablation catheter 81 has an elongated shaft sized and adapted to reach the T11 intercostal vein from an entry point in the femoral or jugular vein. The distal portion of catheter 81 is shown positioned within intercostal vein 55 and includes a distal radiopaque marker 130 aligned with or positioned relative to costovertebral joint 61, an ablation element 131 including or consisting of a distal conductive coiled RF electrode 132 and a proximal conductive coiled RF electrode 133, and an optional inflatable balloon 134 positioned between ablation element 131 and distal radiopaque electrode 130. Distal radiopaque marker 130 is optionally spaced distally from the distal end of ablation element 132 by a distance 135 (e.g., in the range of 0-25 mm (e.g., 0.1-20 mm, e.g., 0.1-15 mm, 0.1-3 mm, e.g., 0.5 mm, 1 mm, or 1.5 mm)). Catheter 81 also includes a proximal radiopaque marker 136 located at or near the proximal end of ablation element 131. In some embodiments, proximal radiopaque marker 136 is spaced axially 0-25 mm from the proximal end of ablation element 131 (which may be from the proximal end of ablation element 133).

[0186] The exemplary axial distances between markers and electrodes described herein (e.g., 0-25 mm, or 0-15 mm) may be incorporated into any other ablation catheter described herein, unless otherwise indicated herein.

[0187] Ablation electrodes 132 and 133 (or any other ablation electrode described herein) may be made, for example, from nitinol wire coiled around the catheter shaft, allowing the electrodes to be flexible enough to traverse the sharp bends from the azygos vein to the intercostal veins and to create long ablations (e.g., 5-25 mm). Nitinol is an example of a superelastic material that allows the ablation element to bend as it traverses an anatomical bend and then elastically return to a straight or straight configuration once the electrode has passed the bend.

[0188] Any distal portion described herein may thus be referred to as having a linear or straight configuration at rest (as manufactured), as opposed to a distal portion that may return to or assume a non-linear rest configuration (e.g., an electrode-carrying distal portion that returns to a coiled configuration).

[0189] Optionally, ablation catheter 81 includes at least one irrigation port 137 (as shown in FIG. 2 ) that is in fluid communication with an irrigation lumen near the coil electrode for delivery of a fluid, such as saline. Saline delivery can facilitate device delivery and removal, or can be delivered during energy delivery to improve ablation formation and prevent overheating, for example. Optionally, catheter 81 can include a guidewire lumen 82 for delivery over a guidewire 79.

[0190] FIG. 8A shows a portion of an exemplary ablation catheter, including at least a portion of its distal section. The ablation catheter of FIG. 8A includes an ablation element, which includes a distal ablation element and a proximal ablation element. This ablation element (and other ablation elements described herein) includes or consists of a distal conductive coiled RF electrode 132 and a proximal conductive coiled RF electrode 133, as shown in FIG. 8A. Both the distal and proximal coiled electrodes may be helical coils positioned around the shaft, at least a portion of which is located on the outer surface of the shaft (optionally within a groove in the shaft). The coiled electrodes may be helical, may not be uniform in direction, pitch, or wire thickness, and may be made from round or ribbon wire of an electrically conductive material (optionally containing a radiopaque material such as platinum iridium), such as stainless steel or superelastic nitinol (optionally electropolished). Alternatively, one or more coiled electrodes may be made from laser-cut tubing, such as Nitinol tubing, that forms a coiled or other flexible pattern. Alternatively, the ablation element (e.g., ablation element 131) may be made from distal and proximal flexible electrodes in the form of a wire mesh or wire braid. Alternatively, the flexible ablation element may include multiple ring electrodes, each having a length of 5 mm or less (e.g., 3 mm). Optionally, the flexible ablation element may have an expandable diameter that can transition from a contracted delivery state to an expanded, deployed state (e.g., an outer diameter of up to about 5 mm) so that it can expand and contact the vessel wall.

[0191] The electrodes described herein, for example, the proximal and distal electrodes described herein (e.g., distal electrode 132 and proximal electrode 133), can range in length from 4 to 12 mm (e.g., 5 to 11 mm), or in some embodiments, they are approximately 5 mm, 5.5 mm, 6 mm, 6.5 mm, 7.0 mm, 7.5 mm, 8 mm, 8.5 mm, 9 mm, 9.5 mm, 10 mm, 10.5 mm, or 11 mm. The proximal and distal electrodes can be the same or approximately the same length, including lengths within the ranges provided herein (e.g., 5 to 11 mm). In some embodiments, the lengths of the electrodes can be different. For example, in some examples, distal electrode 132 can be longer than proximal electrode 133, but the individual electrodes can have any of the lengths described herein. In some examples, distal electrode 132 can be shorter than proximal electrode 133, but the individual electrodes can have any of the lengths described herein.

[0192] If the catheter has multiple electrodes, each electrode may be connected to an independent conductor that runs through the elongate shaft to the proximal portion of the catheter, which conductor may be connected to an extension cable or a source of ablation energy, allowing each electrode to be individually energized in either monopolar or bipolar mode.

[0193] For some catheters having distal and proximal electrodes, the catheters may include a gap between the distal end of the proximal electrode and the proximal end of the distal electrode. In some embodiments, the gap may be in the range of 0 to 5 mm, e.g., 0 to 4 mm, e.g., 0.1 to 1.25 mm, e.g., 0.25 mm, 0.5 mm, 0.75 mm, 1 mm, or 0.25 mm. Preferably, the proximal and distal electrodes are not in electrical communication with each other. Alternatively, the proximal and distal electrodes may overlap at least a portion of each other along their length, provided they are not in electrical communication with each other.

[0194] The gap between the proximal and distal electrodes may not be so large as to prevent the formation of a continuous ablation lesion, with gaps described herein (e.g., 0-5 mm, e.g., 0.1-1.25 mm, e.g., 0.25 mm, 0.5 mm, 0.75 mm, 1 mm, or 1.25 mm) providing exemplary benefits of continuous lesion formation.

[0195] The ablation catheters described herein may include one or more temperature sensors. FIG. 8A shows an exemplary ablation catheter including at least one temperature sensor. The illustrated ablation catheter includes, for example, a proximal temperature sensor 139, which may be located in contact with the proximal electrode 133 and optionally at the proximal end of the proximal electrode 133. The illustrated ablation catheter also includes a distal temperature sensor 140, which may be located in contact with the distal electrode 132 and optionally at the distal end of the distal electrode. Any of the ablation catheters described herein may optionally include another temperature sensor, which may be located between the proximal and distal electrodes or between multiple electrodes. If the catheter includes one or more temperature sensors, the temperature sensors may be thermocouples (e.g., T-type) or thermistors. Optionally, at least one temperature sensor may extend or be radially extendable from the catheter shaft to contact tissue up to 3 mm away from the catheter surface. The temperature sensor may be connectable at the proximal portion of the catheter to a computerized energy delivery console where signals from the sensor may be input and used in an energy delivery control algorithm.

[0196] Any of the ablation catheters described herein may include one or more irrigation ports (sometimes referred to herein as holes or apertures) in fluid communication with an irrigation lumen that is connectable to a fluid source at the proximal portion of the catheter for delivering a fluid, such as saline (e.g., normal or hypertonic saline), to the blood vessel. Ports may be formed in one or more layers of the elongate shaft to provide fluid communication between the ports and the irrigation lumen. The function of the fluid may be to cool (i.e., remove heat from) the electrode and / or the blood vessel wall, flush blood from the blood vessel to reduce the risk of thrombus formation or improve ablation uniformity, conduct electrical energy from the ablation electrode, control intravascular pressure, facilitate delivery of the distal portion of the ablation catheter to the target blood vessel (e.g., an intercostal vein), or facilitate removal of the distal portion of the ablation catheter from the target blood vessel. Optionally, one or more irrigation ports may be distal to the ablation element or distal to each of multiple flexible ablation elements. In some embodiments, any of the irrigation ports may be located radially beneath the flexible ablation element. In some embodiments, one or all of the irrigation ports may be located between the windings of the coiled ablation element, in which case the ports are not located radially beneath the windings of the ablation element. Optionally, irrigation ports may be located in the axial gap or space between adjacent ablation electrodes. Optionally, one or more irrigation ports may be in a cavity of a deployable occlusion structure (e.g., a balloon) and may function to inflate the balloon. The balloon may have a perforation hole on its proximal side that allows fluid to exit the balloon and enter the target region of the blood vessel.

[0197] 8A-10 show the distal portion of the ablation catheter, which includes multiple irrigation ports between the windings of the coiled ablation element (only one port 137 is labeled in the figures, but other ports are visible). In the side views shown in FIGS. 8A, 8B, 9, and 10, the exemplary ports are aligned in a straight line parallel to the longitudinal axis of the distal portion. As further shown in the side views of FIGS. 8A, 8B, 9, and 10, there is an irrigation port between every adjacent pair of windings (even if each of the coiled elements 132 and 133 is formed with a continuous winding along its length). A central axial port 137 between the ablation elements may or may not be present. In any of the embodiments, all ports in the distal portion may be between the windings (in the side views). In other words, in any of the embodiments, there may not be ports radially below the winding structure of the ablation element.

[0198] Optionally, as shown in FIG. 8D , irrigation holes (sometimes referred to herein as apertures or ports) 137 may be located between the windings of the coil electrode and may be dispersed circumferentially along the length of the ablation electrode to deposit saline circumferentially around the electrode. In FIG. 8D , the irrigation holes 137 follow a spiral path, optionally with the same pitch as the coil electrode, and the holes are equally spaced as shown in FIG. 8D . As shown, the embodiment of FIG. 8D does not have a central port between the electrodes (as in the embodiments of FIGS. 8A and 8B ), but the irrigation holes may still be considered to have or follow a spiral path. That is, the spacing between sections of the spiral port may be greater than the spacing between adjacent ports within a section. The embodiment shown in FIG. 8D , however, may include a central irrigation port between the electrodes (similar to the embodiments of FIGS. 8A and 8B ).

[0199] Irrigation holes may be created (e.g., laser drilled) in the tubing (or tubular member) before or after placing or connecting the electrode coil to the tubing. Optionally, the size and number of irrigation holes may be selected along with an irrigation flow rate range to maintain backpressure within the irrigation lumen so that irrigation saline can be ejected through the irrigation holes and blood vessels (e.g., intercostal veins) fill with saline uniformly, consistently, and predictably. For example, an ablation catheter may be adapted to accept a saline flow rate in the range of 30-50 mL per minute during ablation and may have 34 0.003" diameter irrigation holes, or alternatively, 17 0.009" diameter irrigation holes.

[0200] Optionally, there may be more holes associated with a distal electrode than with a proximal electrode, and more holes associated with a proximal electrode than with a distal electrode. Optionally, one or more irrigation holes may be located distal to the distal electrode, e.g., within 3 mm distal to the distal electrode. This may enhance cooling of a distal electrode that includes a temperature sensor in communication with the distal electrode, particularly if the temperature sensor is at the distal end of the distal electrode. For example, as shown in the schematic diagram of the distal portion of the ablation catheter in FIG. 8E , irrigation holes 137 may be arranged in a spiral pattern between at least some of the windings of the proximal helical electrode 133, and similarly, irrigation holes 137 may be arranged in a spiral pattern between at least some of the windings of the distal helical electrode 132, multiple irrigation holes 461 may be arranged distal to the distal electrode, and multiple irrigation holes 460 may be arranged between the proximal and distal electrodes. In this embodiment, the irrigation holes 137 between the turns of the coiled proximal and distal electrodes 133, 132 follow a helical path around the shaft 340 with the same or at least a sufficiently similar pitch as the helical coil electrodes, so that the holes 137 remain between the turns of the coil electrodes. Furthermore, the holes 137 may be spaced apart from one another along the helical path (e.g., every 96 degrees (or at regular intervals between 4 and 110 degrees)), allowing for circumferentially uniform irrigation distribution. The pitch of the coiled electrodes may be tighter at one or both ends of each coil. For example, each end of each coil may form a closed loop at each end of the coil by wrapping around the shaft 340 and contacting adjacent turns of the coil, with the connections soldered together. This may help securely hold the coil to the shaft and contain the ends, avoiding the risk of loose wire ends getting caught on tissue or the delivery sheath. The solder joints may include an RF conductor and optionally thermocouple wire forming thermocouple junctions shown in the figure as distal thermocouple junction 140 at the distal end of distal electrode 132 and proximal thermocouple junction 139 at the proximal end of proximal electrode 133.The closer coil pitch at the ends of the coil reduces the space for irrigation holes. Optionally, irrigation holes may be located only in the center of the coil electrode, and not in the tighter pitch at the ends (e.g., within the first or last three turns). To compensate for reduced irrigation at the ends of the coil electrode when holes are not located in the last few turns, irrigation holes 461 may be located distal to the distal electrode 132, and irrigation holes 460 may be located between the proximal and distal electrodes 133 and 132. For example, the number of distal holes 461 may be in the range of 1 to 5 (e.g., 3), evenly spaced circumferentially (e.g., radially symmetrically), and may be within a distance 462 (e.g., in the range of 0.1 to 3 mm, 0.1 to 1 mm) from the distal end of the distal electrode 132. Similarly, for example, the number of inter-electrode holes 460 may range from 1 to 5 (e.g., 3), be evenly spaced circumferentially (e.g., radially symmetric), and may be within the space 463 (e.g., in the range of 0.5 to 1.0 mm) between the distal electrode 132 and the proximal electrode. As blood flows from distal to proximal in the intercostal veins, the irrigation saline flowing from the distal hole 461 will sufficiently immerse and cool the distal turns of the electrode 132, and the proximal turns of the distal electrode will be cooled by the saline flowing from the inter-winding holes and from the distal hole 461. Similarly, the distal turns of the proximal electrode 133 will be cooled by the saline flowing from the inter-electrode hole 460, and the proximal turns of the proximal electrode will be cooled by the saline flowing from the inter-winding holes and from the hole 460 and other holes 137 and 462 associated with the distal electrode. In one exemplary embodiment as shown in FIG. 8E, the catheter has three evenly spaced distal irrigation holes 461, three evenly spaced irrigation holes 460 between the proximal and distal electrodes, fifteen evenly spaced irrigation holes 137 spirally spaced between the windings of the distal electrode, and fifteen evenly spaced irrigation holes 137 spirally spaced between the windings of the proximal electrode for a total of 36 irrigation holes, each 0.003" in diameter.

[0201] Alternatively, in any of the embodiments described herein, irrigation holes may be located below the coil electrode windings as well as between the windings.

[0202] Alternatively, any of the devices described herein may include a tube section on which the electrodes are disposed, which may be a porous tube (e.g., a mesh or woven tube) made from an inherently porous material.

[0203] Alternatively, any of the coiled electrodes described herein may have a flattened profile, such as a ribbon of conductive material helically wrapped around a tube. A flattened profile may, in some circumstances, facilitate easier delivery through and removal from narrow vessels compared to a round wire profile. FIG. 21A shows an exemplary distal portion of an ablation catheter having an ablation element 385 with multiple coiled electrodes (in this example, first coiled electrode 386 and second coiled electrode 387) made from a flat ribbon helically wrapped around a tubular shaft 388. The flat ribbon may be a conductive material, optionally a superelastic nitinol ribbon shaped into a helical coil, which may have, by way of example only, an inner diameter of 0.069"±0.004" and a pitch of approximately 0.047". Superelastic nitinol has the advantage of being kink resistant and able to elastically return to a preset shape during or after deformation when delivering the device to the target vessel. However, alternative materials such as stainless steel or conductive alloys may also be used. Optionally, at least a portion of the ribbon electrode may be made of a radiopaque material such as platinum iridium. Optionally, the surface of the ribbon electrode may be etched and passivated. The thickness of the flat ribbon may be By way of example only, the flat ribbon electrodes may be in the range of 0.002-0.003", and the width 389 may be in the range of 0.010-0.020". The length 390 of each coil may be approximately 8±0.5 mm. The flat ribbon electrodes may be applied flush with the surface of the tubular shaft. For example, the tubular shaft may be indented where the flat ribbon joins the shaft, or the tubular shaft may be reshaped or softened to allow the flat ribbon to sink into the shaft during application. Alternatively, the flat ribbon electrodes may extend beyond the surface of the shaft, for example by the thickness of the ribbon, which may be in the range of 0.002-0.003".Optionally, the edges 391 of the ribbon electrode (e.g., on the outer diameter) may be rounded, chamfered, or tapered to further facilitate delivery or withdrawal of the catheter into or from the target vessel or to reduce high current densities during RF energy delivery. Irrigation ports 137 may be located between the windings of the flat ribbon electrode, as shown in FIG. 21A or other configurations disclosed herein. Another alternative form of flat spiral electrode may include an assembly made of a conductive material 396, such as superelastic nitinol, stainless steel, or alloy, on a non-conductive substrate 397 (e.g., a flexible circuit), as shown in FIG. 21B, which may facilitate manufacturing. The non-conductive substrate 397 may be, for example, polyimide, and the conductive pattern 396 may be connected to the substrate with an adhesive. The assembly may have wire strain reliefs 398 in the substrate through which conductors extend from a lumen in the catheter shaft to wire solder pads 399, which are in electrical communication with the conductive material 396. Optionally, temperature sensors 139, 140 (such as thermocouples) may be disposed on the wire solder pads along with conductors that provide RF to the electrodes. The thickness of the assembly may range from 0.002 to 0.003", and the thickness of the conductors may range from 0.0015 to 0.0025". The width of each trace may range from 0.010 to 0.020".

[0204] Optionally, the ablation catheter may have a deployable element capable of transitioning from a contracted delivery state (e.g., having an outer diameter in the range of 1.5-3 mm) to an expanded, deployed state (e.g., having an outer diameter in the range of 2.5-6 mm) to one or more of the following functions: anchoring the distal portion of the catheter to a target region of the blood vessel; occluding blood flow; containing delivered fluids such as saline; maintaining vascular patency; or acting as an electrical insulator. For example, as shown in FIG. 8B , any of the catheters described herein may include a distal deployable element 134, which, in combination with optimized irrigation flow, can form a virtual electrode that achieves effective ablation without the need for wall contact. The distal deployable element 134 may be a balloon (e.g., a compliant balloon) as shown in FIG. 8B , or alternatively, a bellows, or a coated stent or mesh. The distal deployable element 134 may be distal to the ablation element, which may include a proximal electrode and a distal electrode as shown in FIG. 8B .

[0205] Optionally, any of the ablation catheters described herein may have a proximal deployable element. Figure 9 shows an exemplary ablation catheter including a proximal deployable element 141, which may be contracted to have an outer diameter in the range of 1.5 to 3 mm in a delivery state and deployed to have an outer diameter in the range of 4 to 10 mm in a deployed state, as shown in Figure 9. The functions of the proximal deployable element 141 may be one or more of: anchoring the distal portion of the catheter to the target region of the blood vessel; occluding blood flow; containing delivered fluids such as saline; acting as an electrical insulator; maintaining vascular patency; acting as a depth stop (e.g., with a deployed outer diameter larger than the target intercostal vein) to prevent the distal portion from advancing too far into the intercostal vein; or directing blood flow in the azygos vein away from the venous ostium to facilitate ablation near the venous ostium. The proximal and distal deployable elements, in combination with optimized irrigation flow, can form virtual electrodes that achieve effective ablation without the need for wall contact. The proximal deployable element can be a balloon (e.g., a compliant balloon) as shown in FIG. 9, or alternatively, a bellows, or a coated stent or mesh. Any of the catheters described herein can include a proximal and a distal deployable element.

[0206] Optionally, any of the ablation catheters described herein may include an intermediate or central deployable element. FIG. 10 illustrates an exemplary ablation catheter including an intermediate deployable element 142, which may be contracted to have an outer diameter in the range of 1.5-3 mm in a delivery state and deployed to an expanded state (e.g., having an outer diameter in the range of 2.5-6 mm) as shown in FIG. 10 . The function of the intermediate deployable element may be one or more of: anchoring the distal portion to a target region of the blood vessel; occluding blood flow; containing delivered fluids such as saline; maintaining blood vessel patency; or acting as an electrical insulator. The intermediate deployable element may be used to isolate the blood vessel between the distal and intermediate deployable elements and around the distal ablation element, forming a virtual electrode that achieves effective ablation without requiring wall contact. Similarly, the section of the blood vessel between the intermediate and proximal deployable elements may also be isolated. The intermediate deployable element may be a balloon (e.g., a compliant balloon) as shown in FIG. 10, or alternatively, may be a bellows, or a coated stent or mesh. In one embodiment where the ablation energy is electroporation, the intermediate deployable element can act as an electrical insulator to more effectively ablate the target nerve by directing the electrical current exiting the blood vessel into the tissue surrounding the blood vessel. In alternative embodiments, the ablation catheter can have only an intermediate and a distal deployable element (i.e., no proximal deployable element), or only an intermediate and a proximal deployable element (i.e., no distal deployable element).

[0207] The above disclosure has provided exemplary methods for positioning an ablation catheter within an intercostal vein to ablate a GSN while minimizing or avoiding damage to non-target structures. The ablation catheters described above, including those shown in FIGS. 8A, 8B, 9, and 10, included one or more radiopaque markers (e.g., distal marker 130 and proximal marker 136) that can be used as part of their positioning methods. While the ablation catheters of FIGS. 8A, 8B, 9, and 10 are examples of ablation catheters that can be used in practicing the methods described herein, it will be understood that the methods can be practiced with a variety of ablation catheters. Accordingly, it will be understood that the methods described herein are not limited to the specific ablation catheters described herein. It will also be understood that the ablation catheters described herein need not be used in the positioning methods described herein.

[0208] Alternative embodiments of TSN / GSN ablation catheters may have one or more of the features described herein, such as spaced-apart proximal and distal radiopaque markers, irrigation lumens, temperature sensors, guidewire lumens, and flexible shaft sections, as described, and may include alternative ablation elements. For example, the ablation elements may be RF electrodes having various configurations or ablation elements delivering various types of ablation energy (e.g., ultrasound, electroporation, cryoablation, laser, chemical, or other ablation modalities). Features of ablation catheters described with respect to one embodiment or example described herein may be incorporated into other suitable embodiments, except where inconsistent with the present disclosure. Features with the same or similar reference numbers are intended to be included optionally and may be the same components.

[0209] For example, FIG. 11 shows the distal portion of one ablation catheter. This ablation catheter includes an ablation element, which may be an RF electrode, with multiple wire struts 143 running the length of the ablation element and aligned around the circumference of the shaft. The wire struts are electrically conductive and made of (e.g.) stainless steel, nitinol, or the like, and are capable of transitioning from a contracted delivery state (e.g., having an outer diameter in the range of 1.5-3 mm) to an expanded, deployed state (e.g., having an outer diameter in the range of 2.5-6 mm) in contact with the vessel wall (particularly intercostal veins). The wire struts may be deployed by applying tension to a pull wire that moves a collar holding or otherwise securing one end of the wire strut, shortening the distance between the two ends and causing the wire strut to bend outward. The struts may be heat-set in a biased configuration, as shown in FIG. 11. Optionally, the RF electrode may include multiple (e.g., two) RF electrodes made of wire struts, positioned adjacent to one another similar to the coiled electrodes shown in Figures 8-10. Optionally, the wire struts may be made from laser-cut tubing. Optionally, the distal end, proximal end, or both, of the expandable wire electrode may have a membrane that functions to occlude a blood vessel when inflated, and can function similarly to the deployable structures (e.g., balloons) shown in Figures 8A-10.

[0210] FIG. 12 shows an exemplary ablation catheter in which an inflatable balloon carries an ablation element. FIG. 12 shows the distal portion of an ablation catheter with an RF ablation element, which comprises one or more conductive elements disposed on an inflatable balloon 144. The conductive elements may be a film, conductive ink, or flexible circuit. Sensors (e.g., temperature sensors) may also be disposed on the balloon. Optionally, the balloon may be inflated by delivering a fluid, such as saline, or air into the balloon. Optionally, the conductive elements or balloon may have perforations to allow fluid to pass through for electrode cooling or energy conduction. The pattern of conductive elements may be cylindrical 148 (FIG. 12), helical 149 (FIG. 13A), multiple electrodes 150 each having a helical configuration (FIG. 13B), electrodes 151 having a wavy (e.g., sinusoidal) or zigzag pattern (FIG. 14), or other patterns adapted to ablate circumferentially around a blood vessel. The embodiments shown in FIGS. 12-14 include optional distal and proximal radiopaque markers that can be used with any of the positioning methods described above.

[0211] Figure 15 shows another exemplary distal portion of an ablation catheter that includes a conductive element within a membrane. The catheter of Figure 15 includes an RF ablation element that is a conductive wire 145 (e.g., a wire coil) on or around the catheter shaft within a cavity defined by a membrane 185. The membrane may be an ionomer, a conductive membrane, or a wettable membrane. Optional distal and proximal markers are shown on the distal and proximal sides of the balloon, respectively.

[0212] FIG. 16 shows an example of a distal portion of an ablation catheter that can be used with the positioning methods described herein. Shown in FIG. 16 is another embodiment of an RF ablation element, where the ablation element is a plurality of short RF electrodes 146 on a tapered shaft 147. This embodiment differs in that the overall length of the shaft carrying the ablation elements can be longer than the previously mentioned 5-25 mm (preferably 10-15 mm). Instead, the catheter includes multiple sections (e.g., two or three) each with a length within this range, which are selectively selected to deliver ablation energy depending on how well they fit within the intercostal veins. The tapered shaft can function to fit within a range of intercostal veins (e.g., in the range of 2.5-5 mm). The distal end is thinner than the proximal end, and the electrodes are individually and selectively energizable. If the distal portion of the catheter is delivered to a relatively small intercostal vein (e.g., approximately 2.5 mm internal diameter), the narrow distal portion may be advanced into the intercostal vein and selected for ablation energy delivery, while the larger proximal portion may remain in the azygos vein and not be used for ablation energy delivery. If the intercostal vein is large (e.g., 5 mm internal diameter), the distal portion may be advanced further into the intercostal vein until the larger electrode penetrates the vessel and contacts its wall. The larger proximal electrode may be selected for energy delivery, while the distal electrode is inactive to avoid damage to the sympathetic nerve trunk. Optionally, the midsection of the electrode may be sized to fit into an intercostal vein with an internal diameter of approximately 3.5 mm. The electrodes may be coiled wire, laser-cut tubing, or solid electrodes. The electrodes may be radiopaque or may have radiopaque markers associated with them, allowing the user to visualize where the electrode is located within the intercostal vein and select which section of the electrode to activate.

[0213] Another embodiment of a transvascular ablation catheter 241 for ablating TSNs or GSNs from within an intercostal nerve is shown in FIG. 17A. The catheter 241 may extend along a longitudinal axis. An expandable member (e.g., in the form of a balloon 242 having an uninflated state and an inflated state) may be coupled to a distal portion 243 of the catheter. The expandable member (e.g., balloon) may have a circumferential treatment zone 248 (e.g., having a length ranging from 5 to 25 mm, such as 10 to 15 mm) that extends along the longitudinal axis and surrounds the blood vessel 55 in the inflated state. The catheter includes an electrode assembly 252, which may include multiple electrode pads 244 and may be mounted or otherwise secured to the balloon 242. Each electrode pad assembly may include a substrate supporting first and second electrode pads, each having a pair of elongated bipolar electrodes and connected to an electrical pattern 249. The electrode pads of each electrode pad assembly may be offset from one another longitudinally and circumferentially. The method may also include inflating a balloon within the intercostal vein so that the electrodes are electrically coupled to the wall of the intercostal vein to redistribute the patient's blood volume for the treatment of conditions such as pulmonary hypertension or heart failure (e.g., HFpEF), and driving bipolar energy between the electrodes of each bipolar pair to therapeutically modify the TSN or GSN within 5 mm of the intercostal vein.

[0214] Each electrode pad may include a temperature sensor disposed between the electrodes of the bipolar pair. Inflation of the balloon may couple the temperature sensor to a wall of the intercostal vein. In some embodiments, the method may further include directing energy to the bipolar pair in response to a temperature signal from the temperature sensor to achieve substantially uniform heating of the wall.

[0215] To create a 5 mm deep ablation to target GSNs from the intercostal veins, cooling the electrode pads can prevent tissue drying of the vein wall, which would otherwise interfere with ablation depth, and allow for greater power delivery. Cooling of the electrodes can be achieved, for example, by circulating a coolant through the balloon 242. In one embodiment, coolant can be infused into the balloon 242 through a coolant inlet port 246 at one end of the balloon chamber, exit the chamber through an outlet port 247 at the opposite end of the balloon chamber, and be allowed to return to the catheter through an outlet lumen.

[0216] In another embodiment, the coolant may be deposited in the bloodstream instead of returning through the catheter lumen. This embodiment may allow for a thinner, more flexible catheter shaft or a larger coolant delivery lumen to increase the flow rate of the coolant. The coolant outlet port may be smaller than the coolant inlet port to allow for increased pressure within the balloon to inflate it. The coolant outlet port may communicate with a lumen that travels to the distal end of the catheter and deposits coolant (e.g., normal saline) into an intercostal vein, rather than a lumen that runs entirely through the catheter shaft to the proximal end. Optionally, the coolant outlet lumen may be the same lumen as the guidewire delivery lumen.

[0217] The electrode pads may be arranged around the balloon to create a circumferential ablation pattern of a length comparable to the target ablation zone 58 (e.g., up to 20 mm, about 15 mm, 12-18 mm). For example, as shown in FIG. 17B, a balloon with electrode pads mounted on an elongate shaft 253 may have an undeployed state with a diameter of about 1-2.5 mm and a circumference of about 3.14-7.85 mm, and may be capable of being inflated to a deployed state with a diameter in the range of about 3-5 mm and a circumference in the range of about 9.4-15.7 mm. The electrode pads 244 may be spaced apart, i.e., spaced apart, by a distance 250 of less than 5 mm (e.g., less than 2.5 mm), with a width or arc length 251 in the range of 3-3.5 mm. The electrode pads 244 may each have a length of about 3-5 mm. As shown in FIG. 17A, the electrode pad assembly 252 may include a plurality of electrode pads 244 arranged in four separate rows, connected to each other by electrical traces 249, and the rows are evenly spaced around the circumference of the balloon 242 (e.g., four rows arranged in 90-degree quadrants). In the longitudinal direction, the pads 244 in one row may be offset from the pads in an adjacent row. When the balloon is in an uninflated state, the electrode pads are spaced apart (e.g., approximately 0-1 mm) and adjacent rows are interlocking. When the balloon is in an inflated state, the pad spacing 250 is increased by the inflatable balloon 242 to approximately 2-5 mm. The balloon 242 may be made of a compliant material, such as latex, or a non-compliant material that flexes and contracts.

[0218] Alternatively, electrode pads may be placed on only one side (e.g., 50%, 40%, 30%, or 25% of the balloon's circumference) to generate a directional ablation pattern that all faces the same side and spans the length of the target ablation zone 58. In the case of a directional ablation catheter, radiopaque markers may be placed on the distal portion of the catheter to indicate the radial direction. For example, the radiopaque markers may be asymmetric and placed on the same or opposite side of the directional electrode pad to be displayed. During use, the physician can rotate the catheter to aim the radiopaque marker, and therefore the electrode pad, away from the vertebrae, which always faces the GSN. Figure 17A shows several small electrode pads. Alternatively, the device may have larger and fewer electrode pads, for example, two or three directional electrode pads (e.g., 3-5 mm in length) on the same side of the balloon that span the target ablation zone 58. A gap (e.g., 1-3 mm) between the electrode pads can facilitate bending the device to traverse from the azygos vein to the intercostal veins. The ablation catheters of Figures 17A and 17B can include proximal and / or distal radiopaque markers and can be used with the positioning methods described herein.

[0219] The catheter shaft just proximal to the balloon may include a flexible neck 245, allowing the ablation balloon to conform to the natural orientation of the intercostal vein. A tight bend radius at this location could result in a stiff shaft exerting force on the ablation balloon, distorting the intercostal vein and reducing the predictability of the ablation zone. The flexible neck may be made of a soft (low durometer) polymer (e.g., Pebax®) with a wire coil embedded in the material, allowing for flexible bending while still providing easy pushability. This type of flexible neck may also be incorporated into the other ablation catheters described herein.

[0220] The most proximal electrode may be placed immediately adjacent to the ostium of the intercostal vein. Blood flow through the azygos vein can metabolically cool nearby tissue, potentially impeding ablation. To compensate for this cooling, the amount and duration of ablation power (e.g., RF) delivered to this proximal electrode may be greater than that of the other electrodes.

[0221] Catheter 241 may have a distal radiopaque marker 255 located distal to ablation element 244 (e.g., distal to balloon 242) and / or a proximal radiopaque marker 254 located proximal to ablation element 244 (e.g., proximal to balloon 242). Distal radiopaque marker 255 and proximal radiopaque marker 254 may be separated by a distance ranging from 5 to 25 mm (e.g., 10 to 15 mm) along the longitudinal axis of the shaft. Any other characteristics or descriptions of radiopaque markers described herein may also apply to markers 255 and / or 254.

[0222] FIG. 18A illustrates an exemplary ultrasound ablation catheter. The catheter 220 includes an elongate shaft 225 having a proximal portion and a distal portion, and an ablation assembly 232 mounted on or located at the distal portion. The ultrasound ablation catheter 220 includes an inflatable balloon 221, which may have a geometry suitable for inflation within an intercostal vein (e.g., an outer diameter 222 in an inflated state ranging from 2.5 to 5 mm) and a length 223 ranging from 8 to 30 mm. Within the balloon 221, multiple ultrasound transducers 224 are disposed on a shaft 233 centrally located within the balloon 221. The transducers 224 may be arranged in series over a length 226 ranging from 5 to 25 mm to generate an ablation of equivalent length, capable of creating an ablation of the length of the target ablation zone 58. The small diameter of the intercostal veins, resulting in a smaller balloon size, poses a risk of contact with or overheating by the transducer, potentially rupturing the balloon or reducing the effectiveness of the ablation. To eliminate this risk, struts or protrusions 227 may be placed between the transducer and the balloon. The struts 227 may be, for example, elastically preformed polymer strands that radiate away from the transducer 224. To create long ablations spanning the target ablation zone, multiple transducers (e.g., three 4 mm long transducers) may be incorporated, spaced apart by flexible gaps 228 between them, facilitating traversal of the tight bending radii from the azygos vein to the intercostal veins. For example, the shaft 225 may be a braided, reinforced polyimide tube with an optional guidewire lumen 229 for delivery over a guidewire 79, which may carry an electrical conductor to energize the transducer 224. The ultrasound transducer 224 may be cylindrical to create a circumferential ablation around the target vein.Alternatively, the ultrasound transducer may be flat or semi-cylindrical to create an ablation that is a partial segment of the vein's circumference, and a radially identifiable radiopaque marker 230 may be placed on the distal portion, allowing the user to direct the ablation toward the front of the patient, where the GSN passes over the vein 55. Optionally, the ultrasound transducer may be configured for imaging and ablation, and the imaging function may be used to evaluate nearby structures such as the lungs, vertebrae, and ribs. Ultrasound imaging may be used to confirm that the transducer is aimed at the lungs (in the direction of the target GSN). Optionally, the shaft may have a flexible neck 231 within 10 mm proximal to the balloon 221 to allow the distal portion to fit snugly within the intercostal vein.

[0223] In an alternative embodiment of an ultrasound ablation catheter, the catheter may comprise an active ultrasound transducer and an inflatable reflector balloon, which may be on the same catheter or, alternatively, on separate catheters. The reflector balloon may have an inflated diameter in the range of 2.5-4 mm and its proximal surface may be shaped (e.g., concave curvature) to focus reflected waves onto the target ablation zone. The reflector balloon is located distal to the transducer and inserted into a small intercostal vein, while the ultrasound transducer resides within the large azygos vein. The ultrasound transducer may be exposed to the blood flow in the azygos vein, or alternatively, may be housed within a chamber within the inflatable balloon filled with a coolant (e.g., a circulating coolant such as sterile water or saline). Ultrasound energy is directed toward the distal reflector balloon, reflected, and focused into the tissue surrounding the splanchnic nerves. The advantage of this approach is that the active ultrasound transducer can be made thicker and does not have to be threaded through the sharp bends between the azygos vein and the intercostal veins. A second advantage is that the same catheter can be used to target ablation in several intercostal veins.

[0224] Catheter 220 may have a distal radiopaque marker 230 located distal to the ablation element (e.g., distal to balloon 221) and a proximal radiopaque marker located proximal to the ablation element (e.g., proximal to the balloon). The distal and proximal radiopaque markers may be separated by a distance ranging from 5 to 25 mm (e.g., 10 to 15 mm) along the longitudinal axis of the shaft.

[0225] 8A-10 illustrate exemplary ablation catheters. The ablation elements included in these embodiments of the ablation catheter include first and second axially spaced flexible coiled ablation electrodes. Having first and second electrodes, rather than a single long electrode, may be beneficial to avoid the tendency of a single long electrode to heat tissue primarily toward one end of the electrode. Thus, having two or more electrodes may aid in creating long, consistent ablations in tissue. Accordingly, FIGS. 8A-10 illustrate embodiments of ablation catheters capable of more consistently creating continuous ablations of a desired length (e.g., 10-25 mm, e.g., 15-25 mm, e.g., 15-20 mm).

[0226] A further exemplary advantage of having first and second electrodes over a single long electrode is that it is possible to energize only a single, relatively short electrode rather than a single long electrode. This can be advantageous when the patient's anatomy requires or could benefit from creating a shorter ablation (e.g., when the azygos vein is perfectly centrally located). In such cases, it may be difficult or dangerous to safely ablate tissue while avoiding non-target structures with a single long electrode, as discussed in more detail elsewhere herein.

[0227] 8A-10 further illustrate ablation catheters in which the first and second ablation elements are axially separated by a gap or spacing that is small enough (i.e., not too large) to form a continuous lesion when the first and second ablation elements are energized, yet large enough to prevent shorting.

[0228] Thus, an exemplary advantage realized by the design features of the distal portion of the ablation catheter described herein (e.g., Figures 8A-10) is that the distal portion can be advanced to a predetermined position within an intercostal vein to reliably create a continuous ablation of at least 10-25 mm in length, while allowing the ablation section to be shortened as needed based on the patient's anatomy.

[0229] In some methods of use, the ablation energy is RF and the energy delivery controller is adapted to deliver RF power in the range of 15 to 50 W. In some embodiments, the controller is adapted to deliver RF power in the range of 15 to 40 W, or in the range of 15 to 35 W, or in the range of 20 to 35 W (e.g., about 25 W, about 30 W, or about 35 W).

[0230] In some methods of use, the energy is delivered over a period of time ranging from 25 to 120 seconds. For example, the energy may be delivered over 90, 100, 110, or 120 seconds, with the energy being delivered to a first electrode for a portion (e.g., half) of that period and to a second electrode for the remaining portion (e.g., half) of that period.

[0231] In some methods of use, the irrigation flow rate during ablation is 10-50 mL / min (e.g., 10 mL / min, 15 mL / min, 20 mL / min). Optionally, the flow rate may be automatically altered by a control algorithm in response to changes in measured temperature, impedance, or phase. The devices and methods disclosed herein allow the TSN to be ablated relatively safely, minimizing or mitigating adverse effects (e.g., pulmonary or other nerve damage). Some method of use embodiments described herein advantageously avoid the challenges of changing thermal and electrical environments during the heating process by temporarily occluding blood flow to reduce the effect of venous collapse. Some method of use embodiments described herein allow nerves to be ablated up to 5 mm from the target vessel. Some of the devices described herein are sized and configured for delivery and positioning in the vasculature designated for ablation of target nerves (e.g., TSN, GSN).

[0232] Some of the devices described herein may have one or more features that allow for safe delivery to the target vessel.

[0233] Some of the devices and methods of use described herein allow for safe delivery of energy with temperature-monitored energy delivery.

[0234] In some of the methods of use described herein, a single positioning and energy delivery can produce lesions capable of targeting nerves up to 5 mm away from the target vessel within a target area with a continuous lesion length of 5 to 25 mm, e.g., 10 to 25 mm, e.g., 15 to 20 mm (e.g., 15 mm, 16 mm, 17 mm, 18 mm, 19 mm, 20 mm).

[0235] Some of the devices and methods described herein are adapted to avoid the risk of boiling, hot spots, or erratic energy delivery that can reduce the effectiveness of ablation. Additionally, some embodiments may include nerve stimulation to distinguish between targeted and non-targeted nerves to confirm positioning before ablation or to confirm technical success during or after ablation.

[0236] It is believed preferable, but not required, that the ablation method create a continuous ablation zone (i.e., not having separate, discrete regions of ablated tissue that are not connected to one another). This maximizes the likelihood that the ablation energy will effectively ablate the tissue region where the target GSN nerve or GSN nerve root is likely to be located. The continuous ablation zone may be circumferential or may be less than circumferential.

[0237] An ablation confirmation test may then optionally be performed, for example, by delivering a neural stimulation signal. A physiological response to the ablation confirmation test (e.g., splanchnic vasoconstriction, increased heart rate, increased blood pressure) may be monitored. If the physiological response indicates that the first lesion did not achieve clinically significant GSN blocking (e.g., by observing a lack of physiological response), ablation energy may be delivered from the ablation catheter to create a second lesion in tissue up to 5 mm from the second intercostal vein. The distal portion of the ablation catheter may be moved to a third intercostal vein above (e.g., above and adjacent to) the second intercostal vein. The same or another ablation confirmation test may be performed, followed by further monitoring tests. If the physiological response indicates that the first and second lesions did not achieve clinically significant GSN blocking (e.g., by observing a lack of physiological response), ablation energy may be delivered from the ablation catheter to create a third lesion in tissue up to 5 mm from the third intercostal vein. Any of these ablation confirmation tests may include delivering a neural stimulation signal configured to generate action potentials in the thoracic splanchnic nerve from a stimulation electrode positioned on a distal portion of the ablation catheter. Alternatively or additionally, the ablation confirmation test may include a leg raise test. Alternatively or additionally, the ablation confirmation test may include adding a fluid volume to the venous system. Alternatively or additionally, the ablation confirmation test may include a hand grip test. Alternatively or additionally, the ablation confirmation test may include measuring venous compliance or venous capacitance.

[0238] In an exemplary method in which the ablation confirmation test includes a leg-raising test, the method may include any of the following steps: A baseline measurement may be obtained prior to ablation in the lowest intercostal vein, which may be done by raising the leg, measuring the change in central venous pressure, and waiting for equilibrium (i.e., measuring total venous compliance, including the central veins and the splanchnic bed). The leg may then be lowered, allowing equilibrium and redistributing blood flow to the leg. An ablation in the lowest intercostal vein (e.g., T11) may then be performed as described herein. The leg may then be raised, after which equilibrium is allowed and the central venous pressure is remeasured. A measurement may then be taken to determine whether there has been an appropriate decrease in total venous compliance. If there has been, the ablation of the GSN has been successful. If there has not been, an ablation in the next higher intercostal vein (e.g., T10) may be performed as described herein. This measurement may then be repeated. It may then be determined whether there has been an appropriate decrease in total venous compliance. If there has been, the ablation of the GSN has been successful. If not, ablation at the next higher intercostal vein (e.g., T9) may be performed.

[0239] An exemplary method in which the ablation confirmation test includes a gripping activity or other activity that increases sympathetic nervous system (SNS) outflow to the splanchnic bed may include the following steps: An ablation may be performed in the lowest intercostal vein (e.g., T11). Venous compliance may then be measured. A gripping test may then be performed for a predetermined length of time (e.g., 60 seconds). Venous compliance may then be re-measured. If there is no change in venous compliance, the first ablation was sufficient to achieve a clinically significant result. If there is still a decrease in compliance, some of the SNS activity caused by the grip has not yet ended. Therefore, the ablation in the lowest intercostal vein was insufficient to achieve a clinically significant result. Next, an ablation may be performed in the next higher intercostal vein (e.g., T10). A gripping test may be performed for a predetermined length of time (e.g., 60 seconds). Venous compliance may then be re-measured. If there is no change in compliance, a second ablation was sufficient. If there is a decrease in compliance, some of the SNS activity caused by the grip has not yet ended, and ablation of the next higher intercostal vein was insufficient to achieve a clinically significant result. Next, ablation of the next higher intercostal vein (T9) may be performed. At this point, the procedure is complete, as ablation is not intended above the third lowest intercostal vein.

[0240] Energy Delivery Algorithm

[0241] One aspect of the disclosure described herein relates to an energy delivery algorithm adapted to be particularly suitable for circumferentially ablating tissue around small blood vessels (e.g., intercostal veins or other similar vessels) to a depth of at least 5 mm and up to 10 mm from an ablation catheter. The ablation catheter may be any of the catheter embodiments shown in Figures 1, 2, 8A, 8B, 8C, 8D, 8E, 9, 10, 21A, and 21B, and the ablation catheter includes first and second electrodes (e.g., two coiled electrodes, each having a length ranging from 2.5 to 10 mm, preferably 5 to 8 mm, an outer diameter ranging from approximately 1.5 to 3 mm, and a spacing between the electrodes ranging from 0 to 5 mm).

[0242] In a first embodiment of the energy delivery algorithm, called "multiplexed monopolar RF," pulses of RF are delivered to multiple (e.g., two) electrodes in a monopolar configuration with an asynchronous waveform. Each electrode receives a pulsed RF energy waveform that alternates on and off at a steady frequency. The waveform may be, for example, a square wave, a sine wave, or another form of alternating waveform. An ablative level of RF power is delivered during the on-time, and a non-ablative level of RF power (e.g., in the range of 0-1 W, e.g., approximately 0.1 W) is delivered during the off-time. The waveforms for each electrode are asynchronous; that is, they are aligned in time such that the on-time of one electrode is aligned with the off-time of the other electrode, and the off-time of one electrode is aligned with the on-time of the other electrode. The algorithm has an ablation mode, which is initiated by user activation (e.g., pressing a button or foot pedal). The ablation mode algorithm may include parameters, as shown in FIG. 19, which may be optionally user-defined, may be at default settings until the user changes them, or may be automatically defined. Note that Figure 19 is not drawn to scale and the total time t TOTALare drawn abbreviated to simplify the parameters and concepts. For example, if the total time was 180 seconds and both the first and second electrode pulse widths were 2 seconds each, the correct plot would show 45 cycles, but for simplicity, fewer cycles are shown. The parameters are the initial power P i , the pulse width of the first electrode PW1, the pulse width of the second electrode PW2, and the total treatment time t TOTAL , minimum treatment time, lockout time t LO , a second power P2, and optionally, a lower power level. i refers to the amplitude (in watts) of radio frequency power initially delivered to each of the ablation electrodes (e.g., the proximal electrode 133 and distal electrode 132 shown in Figures 8A, 8B, 8C, 8D, 8E, 9, and 10) at the start of an energy delivery protocol. The initial power may be selectable in the range of 15-50 W, preferably in the range of 20-50 W, with a default setting of 35 W (e.g., for a flow rate in the range of 10-50 ml / min). The first electrode pulse width PW1 is the duration of each pulse of RF energy (i.e., the ablation portion of the waveform) delivered to the distal electrode 132, and may be selectable in the range of 0.5-4 seconds (e.g., 1-3 seconds, preferably 2 seconds), with a default setting of preferably 2 seconds. The second electrode pulse width PW2 is the duration of each pulse of RF energy (i.e., the ablation portion of the waveform) delivered to the proximal electrode 133 and may be selectable from 0.5 to 4 seconds (e.g., 1 to 3 seconds), with a default setting of preferably 2 seconds. Some embodiments may have three or more electrodes and may have pulse width parameters associated with each electrode accordingly. The off-time of one electrode waveform may be the same duration as the on-time of the other electrodes. In an embodiment having four electrodes, the alternating electrodes (e.g., the first and third electrodes) may be synchronized with each other and asynchronous with the other electrodes (e.g., the second and fourth electrodes). The total treatment time t TOTALis the duration of time from the start to the end of delivery of ablation energy, and may be selectable in the range of 60 to 400 seconds (e.g., 120 to 200 seconds), and may preferably be 180 seconds. The minimum treatment time is an optional portion of the total treatment time (e.g., less than or equal to the total treatment time) that begins at the start of delivery of ablation energy, and if the temperature or impedance reaches a limit before the completion of the minimum treatment time, the power may be reduced to a second power level or a subsequent lower power level, and if the temperature or impedance reaches a limit after the completion of the minimum treatment time, the power may be reduced to zero (e.g., the delivery of ablation energy may be terminated). The lockout time t LO is the time allowed for the tissue temperature to respond (e.g., decrease in temperature) after an event that triggers a response (e.g., temperature or impedance exceeding a limit, the algorithm responding to a power drop, etc.). During the lockout time, the algorithm may ignore temperature or impedance measurements for either the electrode associated with the trigger or all electrodes unless they indicate a critical error, such as a critical upper temperature limit T CU (e.g., 105°C or higher), critical lower limit temperature T CL (e.g., below 20°C), critical upper limit impedance Z CU (e.g., >800 Ω, >900 Ω, >1000 Ω, user-selectable value between 800 and 2000 Ω), or a critical lower impedance Z that may indicate equipment damage. CL (e.g., 50Ω or less). The lockout time may be selectable in the range of 2 to 7 seconds, or alternatively, the default setting may be 5 seconds, with a time length from one pulse width to a maximum of four pulse widths. The second power P2 refers to a radio frequency power amplitude (in watts) that is less than the initial power, e.g., 5 to 10 W less than the initial power. The limit temperature T L or limit impedance Z (for example, in the range of 200 to 500 Ω) LThe power level is changed to a second power if the temperature sensor senses a limit temperature T (e.g., distal electrode 132 or proximal electrode 133) or is associated with a temperature sensor that senses a limit temperature T (e.g., distal temperature sensor 140 or proximal temperature sensor 139) or is associated with an electrode across which a limit impedance is measured. Alternatively, if the temperature measured by one of the temperature sensors is greater than or equal to the limit temperature T L If the power to all electrodes exceeds the second power, the power to all electrodes may be reduced. Optionally, the algorithm parameters may further include a power level less than the second power, e.g., a third power level, a fourth power level, etc. Alternatively, instead of the second power, a power decrement P may be included as a user-defined parameter. d It is good to have a power decrement P d is the amount of power amplitude reduction triggered by exceeding the temperature limit or impedance limit, and may be selectable in the range of 1-30 W, with a default of 5 W. Optionally, the power decrement may be variable or calculated as a percentage of the previous power level (e.g., a percentage in the range of 1-30%). If the power is reduced to an absolute level, such as a second power, or by the power decrement, and a minimum power Pmin (e.g., in the range of 1-10 W, e.g., 5 W) is reached and the temperature is still above the temperature limit or the impedance is still above the impedance limit, the algorithm may respond by a) terminating delivery of ablation power to the electrode associated with the trigger and continuing delivery of ablation power to the other electrodes using the current alternating waveform or in the form of continuous RF, b) terminating delivery of ablation power to all electrodes, c) increasing the flow rate of irrigation fluid, or d) adjusting the temperature limit. If treatment is terminated due to failure to maintain a temperature below a limit temperature or impedance below a limit, or due to some other error, the algorithm may instruct the user to reposition the device, remove and inspect the device, or inspect the equipment setup.

[0243] Upon user activation, saline may be pumped from the irrigation source, through the catheter, and out of irrigation port 137. This may be done to prime the irrigation lumen or test functionality before the device is placed in the patient, or may be done while the device is being advanced into position or during device withdrawal to facilitate delivery or withdrawal; the flow rate or pumping speed during delivery or withdrawal may be user-selectable in the range of 0-50 mL / min. Optionally, ablation will not begin unless flow is turned on in the range of 15-30 ml / min.

[0244] Saline tracking is a function that has an algorithm that calculates the volume of saline delivered to the patient, which may be done by multiplying the flow rate by the elapsed time or by calculating the area under a plot of the flow rate used to deliver saline to the patient's vasculature against time, and the calculated volume is displayed on a user interface (e.g., a computerized console). Additionally, the algorithm may determine whether the portion of the catheter that delivers irrigation fluid is external or internal to the body through manual input or through an automatic detection algorithm that uses one or more input signals, such as temperature sensed by a temperature sensor on the catheter (e.g., sensor 139 or 140 in FIG. 8A ), monopolar impedance, or bipolar impedance. If the algorithm determines that the catheter is internal to the patient (or within a delivery sheath inserted into the patient), all saline pumped by a pump connected to the computerized console is considered in calculating the volume of saline delivered to the patient. If the algorithm determines that the catheter is not inside the patient, any saline pumped by the pump connected to the computerized console is not considered in calculating the volume of saline delivered to the patient. This feature helps the user calculate how much saline has been introduced into the patient's fluid system, which may be of concern to some patients. Optionally, an alarm may be triggered if the volume of saline reaches or approaches a predetermined value. If the device is outside the body, the saline irrigation flow rate may be turned on, for example, to prime the irrigation lumen or to test the functionality of the catheter and irrigation system. To calculate how much volume has been delivered to the body, the saline tracking algorithm may identify, via manual input, whether the catheter is inside or outside the body. This may be done by having the user press an actuator when the catheter is inside the body, which signals the algorithm to begin calculating volume when the pump is activated.If the catheter is removed from the body, the user may press the actuator to signal to the algorithm that the catheter is no longer in the body and the calculation accumulating saline volume is paused. Any volume delivered outside the body is not included in the calculation of the volume of saline delivered to the patient. If this or another catheter is returned to the patient for a subsequent treatment, all saline delivered to the patient is added to the volume calculation by the user pressing the actuator to resume tracking. Alternatively, the saline tracking algorithm may automatically identify whether an irrigated ablation catheter is in the body by monitoring monopolar impedance measured between one or more ablation electrodes and a ground pad, or alternatively, by monitoring bipolar impedance measured between two ablation electrodes. Monopolar impedance has an advantage over bipolar impedance for detecting in vivo versus ex vivo conditions. This is because monopolar impedance is the impedance of the electrical circuit from at least one of the electrodes on the catheter, through the body, to a distributed grounding pad attached to the patient's skin, while bipolar impedance is the impedance of the circuit from a first electrode on the catheter, through a conductive medium, to a second electrode on the catheter. The conductive medium may be within the patient's body, such as blood or tissue, but may also include saline or a conductive medium outside the body, such as when the electrodes are immersed in a saline bath or when saline is irrigated through the catheter to moisten the electrodes completing the circuit. However, bipolar impedance may still be used to detect environmental changes and may be useful in saline tracking algorithms. When impedance is measurable because no ablation therapy is being performed, very low (non-ablative, e.g., 0.1 W) power may be delivered.For example, in monopolar mode, when the catheter is inside the body and connected to the console, and the grounding pad in electrical communication with the console is connected to the patient's skin, the monopolar impedance can be within a certain range that is distinguishable from a catheter outside the body. For example, as determined empirically, a monopolar impedance measurement in monopolar mode between 700 and 900 Ω indicates that the distal portion of the catheter, including the electrodes and irrigation lumen, is inside the sheath and within the patient's vasculature; an impedance measurement that is significantly lower than the sheathed impedance (e.g., between 80 and 130 Ω), indicates that the distal portion is inside the vasculature and outside the sheath; and a monopolar impedance above a high impedance threshold (e.g., above the high impedance threshold, or 900 Ω, 2000 Ω, or 3000 Ω) indicates that the electrodes are outside the body or that the grounding pad is improperly connected. Alternatively, if the bipolar impedance (e.g., measured by passing a current through a conductive medium between two ablation electrodes at the distal portion of the catheter) is in the range of approximately 300-600 Ω (e.g., approximately 500 Ω), the distal portion is within the sheath and inside the body; if the bipolar impedance is in the range of 60-80 Ω, the distal portion is within the vasculature and outside the sheath; if the bipolar impedance is above a high impedance threshold (e.g., above 600 Ω, 900 Ω, 2000 Ω, or 3000 Ω), the electrodes are outside the body or the catheter's electrical circuitry is broken. The algorithm may determine that the distal portion of the ablation catheter from which saline is being released is inside the body if the measured impedance is below the high impedance threshold, in which case the accumulated saline volume is taken into account; if the measured impedance is above the high impedance threshold, the algorithm may determine that the distal portion is inside the body, in which case the saline pumped during this scenario is not taken into account in the volume accumulation. Optionally, if a change in in vivo / ex vivo conditions is detected, the algorithm may display a message asking the user to acknowledge the change.Optionally, the user may input a known volume of saline injected by other means (e.g., saline injected along with a control fluid injected from a syringe into the delivery sheath), which may be added to the accumulated volume calculation.

[0245] Figure 20 shows a machine state diagram for the automatic saline tracking algorithm. On the main treatment screen 321, with the ablation catheter connected to the console and external to the body, and grounding pads connected to the patient and console, the user may first press button 325 to enable saline tracking (326). This can initiate an automatic calculation of the volume of saline pumped, which determines how much of the saline volume will accumulate inside the body and, optionally, how much will be pumped while the catheter is outside the body. Once the ablation catheter is inserted inside the body, the bioelectrical impedance should drop to a range indicating tissue contact (322), and a message (323) is displayed suggesting the user start saline tracking. The user may press button 324 to acknowledge this message, which instructs the algorithm to include the accumulated saline pumped in the total accumulated saline volume accumulated inside the body. When the catheter is removed from the body, an impedance rise outside the range associated with body contact is measured (327), and a message automatically appears suggesting the user pause (328) saline tracking. The user may press button 329 to acknowledge the message, which instructs the algorithm to exclude the accumulated saline pumped from the total accumulated saline volume accumulated in the body. Additionally, the user may press button 330 at any time to pause (331) saline tracking, i.e., to pause the inclusion of the pumped saline volume in the calculation of saline accumulated in the body. Alternatively, instead of automatically indicating that the catheter is inside the body based on impedance, the algorithm may alert the user that the catheter is believed to be outside the body, and the user may manually select that flow rate should be excluded from the saline tracking total. The user may reset the volume total to zero by pressing the reset actuator.

[0246] An alternative saline tracking algorithm may ignore rapid increases in impedance within a predetermined amount, which may be caused by injection of contrast or saline near the ablation electrodes, while the catheter is in the body to avoid false positives. To distinguish between injecting contrast or saline and withdrawing or inserting the distal portion of the catheter from the patient when a large change in impedance is detected, the algorithm may have two impedance thresholds, which are used depending on whether the system is in in vivo or ex vivo mode. A first impedance threshold (e.g., approximately 500 Ω, in the range of 400-600 Ω) may be used when the catheter is not in the patient (i.e., ex vivo), and a drop in impedance below this first impedance threshold may automatically indicate that the catheter is inserted. A second impedance threshold (e.g., approximately 900 Ω, in the range of 800-3000 Ω) may be used when the catheter is inside the patient (i.e., in vivo), and a rise in impedance above this second impedance threshold can automatically indicate that the catheter has been removed from the body. For example, an ablation catheter may be outside the patient's body, while the impedance may be above the second threshold (e.g., 900 Ω). If the saline pump is operating, the algorithm determines that the catheter is not inside the body, and the volume of saline is not included in the cumulative calculation. The catheter may be inserted into the patient, while the impedance may drop below the first threshold (e.g., 500 Ω), in which case the algorithm determines that the catheter is inside the body, and all movement of the pump is considered in the cumulative calculation. When saline or control solution is injected, the impedance may rise above the first threshold, but because the catheter is inside the body, the algorithm determines that the rise does not indicate withdrawal, and therefore all pump activity continues to be considered in the cumulative calculation.If the catheter is withdrawn from the body, the impedance rises above a second threshold (e.g., 900 Ω), the tracking algorithm determines that the catheter has been withdrawn, and pump activity is not considered in the accumulation calculation at all. Optionally, the first and second thresholds may be adjusted or selected in user settings. To ensure that the algorithm functions properly, the catheter may be specified for use with a uniform concentration of saline (e.g., 0.9% normal saline).

[0247] In addition to calculating the cumulative amount of saline injected, the algorithm may optionally vary other functional behavior depending on whether the system is in in vivo or ex vivo mode (e.g., as shown in Table 1). [Table 1]

[0248] Another use of algorithmic bipolar impedance monitoring may be to display a message to the user asking them to verify that the distributed ground pads are properly connected if the bipolar impedance is low (e.g., less than 500 Ω) and the monopolar impedance is high (e.g., greater than 900 Ω).

[0249] Another use of algorithmic bipolar impedance monitoring may be to display a message to the user asking if there is an open circuit on one or both electrodes when the bipolar impedance is high (e.g., greater than 900 Ω), the irrigation pump is running, and the system is in in vivo mode.

[0250] During the ablation mode algorithm, a pump may be activated to irrigate saline through the irrigation port 137 at a flow rate ranging from 15 to 30 ml / min (e.g., for a period of 5 seconds) before delivery of ablation energy begins. Radio frequency electrical energy (RF) (e.g., having a frequency ranging from 350 to 500 kHz) is then delivered from the computerized energy console to a first electrode (e.g., the distal electrode 132) of the plurality of electrodes in a monopolar mode (i.e., through the ground pad and back) at an initial power for a duration equal to the pulse width (e.g., the pulse width of the first electrode). RF delivery to a second electrode (e.g., the proximal electrode) then begins at the initial power for a duration equal to the pulse width of the second electrode, while the first electrode (e.g., the distal electrode) enters the first electrode's off time (e.g., at 0 W or a low power of less than 1 W) of the waveform. Optionally, if the ablation device has three or more electrodes, power delivery to subsequent electrodes may be performed for an appropriate pulse width before power delivery to the first electrode is repeated. Alternatively, power delivery to the electrodes may be performed in other orders or combinations without departing from the spirit of the disclosure herein. The multiplexing of RF power through each electrode continues for the total treatment time unless an event is triggered that tapers or stops the delivery of ablation RF.

[0251] Throughout the ablation mode algorithm, and optionally before or after, temperatures may be measured by temperature sensors (140 and 139 in FIGS. 8A, 8B, 9, and 10) and the temperatures may be displayed on the console. If these temperatures exceed a predetermined limit temperature T L It can be compared with T LThe temperature may range from 40 to 95°C, preferably 90°C. Because the intravascular space around the electrodes and temperature sensor is irrigated, the measured temperature can be expected to be lower than the temperature of the hottest tissue. Because blood vessel size and shape vary, the relationship between the measured temperature and the temperature of the hottest tissue or ablation volume can also vary. However, if the measured temperature is higher than the limit temperature, this may indicate excessive power. The limit temperature may be considered a safety control above which the measured temperature should be reduced. On the other hand, if the measured temperature falls below the limit temperature, this does not necessarily indicate that the tissue is too hot. If the measured temperature remains below the limit temperature throughout the total treatment time, the RF power remains at the initial power. If one of the measured temperatures exceeds the limit temperature T L Exceeds or optionally T L In this case, treatment (total treatment time) t TOTAL During, or optionally before the completion of the minimum treatment time, the power may be reduced to a second power P2, preferably for the active electrode as shown in FIG. 19 , or alternatively, for the electrode associated with the measured temperature, or for all electrodes. If the measured temperature is expected to drop below the limit temperature within about 5 seconds (or about 2-3 pulse widths) after the power reduction, but does not do so, or if it does but rises above the limit temperature again before the completion of the total treatment time (or optionally the minimum treatment time), the power may be reduced to 0 W or a lower level less than 1 W, preferably for all electrodes, or alternatively, for the active electrode or the electrode associated with the measured temperature. Alternatively, the power may be reduced to a third power or a subsequent power. If, after the completion of the minimum treatment time, any of the measured temperatures reaches or exceeds the limit temperature, the power may be reduced to 0 W or a lower level less than 1 W instead of tapering to a lower ablation level.

[0252] Optionally, the ablation mode algorithm further defines a limit impedance Z L, which may be in the range of 200-500 Ω, preferably 500 Ω, and may be indicative of tissue desiccation. If the monopolar impedance measured from one of the electrodes in electrical communication with the ground pad rises above the limit impedance, delivery of ablation energy to that electrode may be terminated to avoid vapor formation or damage. Optionally or additionally, if the limit impedance is exceeded before completion of the minimum treatment time, the power of the ablation RF energy may be reduced to a second power, or optionally, to another lower power level on subsequent occurrences. As shown in FIG. 19, if the impedance for all electrodes exceeds the limit impedance Z L remains smaller than the critical lower limit impedance Z CL If it remains larger, the power of each electrode does not change as a result.

[0253] Optionally, if the temperature or impedance for a particular electrode exceeds a limit temperature or limit impedance when the second power is being delivered, the ablation RF power may be reduced to 0 W, preferably for the active electrode, or alternatively for the electrode associated with that sensor, or for all electrodes.

[0254] Optionally, the total treatment time or minimum treatment time (if included) may be extended when the power is reduced to a second power or to an optional subsequent lower power level, e.g., to match the amount of energy that would be delivered if the power had not been reduced.

[0255] The algorithm considers the critical upper temperature limit T in addition to the temperature and impedance limits. CU , the critical lower limit temperature T CL , critical upper impedance Z CU , and the critical lower limit impedance Z CL The critical upper limit temperature T CUmay be used to identify a damaged temperature sensor or an ultimately high tissue temperature that is undesirable to exceed, and may be 105° C. or higher. CL can indicate something is wrong with the installation or device damage and may be below body temperature (e.g., 35°C). CU The critical lower impedance Z may be used to identify catheter damage (e.g., broken wires or improperly applied ground pads) and may range from 800 to 2000 Ω. CL may be used to identify catheter damage (e.g., short circuit or electrode damage) and may be less than 20 Ω.

[0256] Optionally, the energy delivery algorithm may include a bipolar RF component, in which RF current passes from a first electrode to a second electrode (bipolar mode). Bipolar RF can concentrate current density between the two electrodes, generating an ablation pattern that heats the tissue between the electrodes more intensely than if the two electrodes delivered monopolar RF independently. The bipolar RF component may be added at the beginning or end of the multiplexed monopolar RF treatment. For example, the bipolar RF component may have a duration ranging from 30 to 120 seconds, preferably about 60 seconds, deliver power at an initial level ranging from 10 to 50 W (e.g., 20 to 35 W, preferably about 30 W), and may be delivered either before or after the multiplexed monopolar RF treatment.

[0257] Alternatively and optionally, the ablation waveform may be similar to the multiplexed monopolar RF algorithm, but may have an additional pulse width at which the electrodes deliver bipolar RF. For example, the bipolar pulse width may be in the range of 0.5 to 5 seconds (e.g., 2 seconds). The waveform may include alternating cycles of monopolar RF from a first electrode over a first pulse width, monopolar RF from a second electrode over a second pulse width, and bipolar RF between the first and second electrodes over repeated bipolar pulse widths. If the ablation catheter has three or more electrodes, the waveform may include repeated cycles of monopolar RF for each electrode over its respective pulse width and bipolar RF between each adjacent pair of electrodes over the bipolar pulse width.

[0258] An alternative embodiment of an ablation energy delivery algorithm used to create the desired lesion for GSN ablation is called "Sequential Monopolar with Bipolar Fill," in which ablative RF energy is delivered to a first ablation electrode (e.g., distal electrode 132 shown in FIGS. 1, 2, 8A, 8B, 9, and 10) in monopolar mode for the first electrode's monopolar duration, then to a second ablation electrode (e.g., proximal electrode 133) for the second electrode's monopolar duration, and then ablative RF energy is delivered between the first and second electrodes in bipolar mode at an initial bipolar power for the bipolar duration. If the temperature measured by a temperature sensor associated with the electrode receiving the ablation energy increases above the monopolar upper temperature limit, the initial monopolar power of RF energy may be reduced to the second monopolar power, or alternatively, by a power decrement. If the temperature rises above the upper temperature limit again while the reduced power is being delivered, the power may be reduced again, either to a third power or by a power decrement. Optionally, the user may define parameters such as the initial power to each ablation electrode, the monopolar duration of the first and second electrodes, the power decrement, or the second, third, etc. monopolar power. Similarly, if the measured temperature from any of the temperature sensors associated with the active electrodes rises above the bipolar upper temperature limit during the bipolar phase, the initial bipolar power may be reduced to a second bipolar power or by a power decrement.

[0259] Initial monopolar power is the amplitude of RF power initially delivered to either ablation electrode during the monopolar phase and may be selectable in the range of 20-50 W, with a default setting of 25 W.

[0260] The first electrode monopolar duration is the length of time that ablation RF energy is delivered to the first electrode in monopolar mode and may be selectable in the range of 30 to 180 seconds, with a default setting of 60 seconds.

[0261] The second electrode monopolar duration is the length of time that ablation RF energy is delivered to the second electrode in monopolar mode and may be selectable in the range of 30 to 180 seconds, with a default setting of 60 seconds.

[0262] The second monopolar power is an RF power amplitude smaller than the initial monopolar power and is triggered when the measured temperature rises above the upper temperature limit. This can be selectable from 10 to 50 W as long as it is below the initial monopolar power, with the default setting being 20 W.

[0263] The monopolar power decrement is an alternative to the second monopolar power (and optionally the third, etc. monopolar power) and is the amount of power reduction triggered by the measured temperature increasing above the monopolar upper temperature limit, and may be selectable in the range of 1-20 W, with a default setting of 5 W.

[0264] The initial bipolar power is the amplitude of RF power initially delivered to the two ablation electrodes (e.g., two electrodes that were previously activated with monopolar RF) during the bipolar phase and may be selectable in the range of 10-50 W, with a default setting of 20 W.

[0265] Bipolar duration is the length of time that ablation RF energy is delivered to the two electrodes in bipolar mode and may be selectable in the range of 10 to 180 seconds, with a default setting of 20 seconds.

[0266] The second bipolar power is a smaller RF power amplitude than the initial bipolar power and is triggered when the measured temperature rises above the bipolar upper temperature limit. This may be selectable from 5 to 50 W, as long as it remains below the initial bipolar power, with a default setting of 15 W.

[0267] The bipolar power decrement is an alternative to the second bipolar power (and optionally the third, etc. bipolar power) and is the amount of power reduction triggered by the measured temperature increasing above the bipolar upper temperature limit, and may be selectable from 1 to 20 W, with a default setting of 5 W.

[0268] The monopolar upper temperature limit is the threshold temperature that is compared to the monopolar measured temperature during the monopolar phase. This may be selectable between 60 and 90°C, with a default setting of 90°C.

[0269] The Bipolar Upper Temperature Limit is a threshold temperature that is compared to the Bipolar Measured Temperature. It may be selectable between 60 and 90°C, with a default setting of 90°C.

[0270] Optionally, if the upper temperature limit is exceeded during either the monopolar or bipolar phase, the initial power may be reduced to a second power or power decrement (optionally with the electrode in the same position), and the duration may be repeated. If the upper temperature limit is still exceeded, treatment may be terminated with an error message. The user may attempt the ablation procedure with a repositioned electrode or with a new catheter.

[0271] Optionally, the algorithm may have a monopolar upper impedance limit, which is a threshold impedance that is compared to the monopolar measured impedance during the monopolar phase, which may be selectable in the range of 150-300 Ω, with a default setting of 200 Ω.

[0272] Optionally, the algorithm may have a bipolar upper impedance limit, which is a threshold impedance that is compared to the bipolar measured impedance during the bipolar phase, which may be selectable in the range of 100-300 Ω, with a default setting of 150 Ω.

[0273] The following disclosure provides some exemplary methods of use and their steps. Some embodiments of the methods of use may include one or more of the following steps, the order of which may be varied in some cases, and not all of which must be performed. The methods described herein may include interventional access, which may include one or more of the following steps, to treat a patient with anticoagulation therapy compatible with venous interventional procedures: the patient's right chest; tracing the standard technique for femoral, clavicular, or jugular vein puncture, guidewire insertion, and sheath placement, using heparinized saline as needed; placing a 0.035 exchange length guidewire (e.g., Cordis Amplatz Super Stiff 260 cm or equivalent); advancing a 6F general-purpose catheter (e.g., JR4 or equivalent) over the guidewire to the azygos ostium; injecting a bolus of radiopaque contrast using the 6F general-purpose catheter to identify the azygos ostium under fluoroscopy; engaging the azygos ostium with the guidewire and 6F general-purpose catheter and advancing the guidewire through the valve (if present) into the azygos vein; and exchanging the 6F general-purpose catheter for an azygos vein access sheath (which may be 9F and at least 100 cm in length, e.g., Arrow 9F Super Arrow Flex Introducer). The ablation procedure may include one or more of the following steps: positioning an azygos vein access sheath (e.g., a ChoICE Pt LS Floppy or equivalent) at approximately the T9 level; adjusting the C-arm off the vertical axis to obtain the best visualization of the azygos vein tree using contrast imaging prior to introduction of the ablation catheter; loading a 0.014 exchange length guidewire (e.g., a ChoICE Pt LS Floppy or equivalent) into the azygos vein access sheath; and advancing and placing the 0.014 guidewire deep into the first target intercostal vein (e.g., the T11 intercostal vein).

[0274] The methods described herein may include preparing the device, generator, and accessories, which may include one or more of the following steps: inspecting the catheter package prior to use, opening the ablation catheter package using aseptic technique, removing the catheter from the package and placing it in the sterile field while maintaining sterility, carefully visually inspecting the electrodes and ablation catheter for integrity and general condition, filling a 10 cc or larger syringe with saline and connecting the syringe to the guidewire lumen hub on the handle of the ablation catheter, flushing the guidewire lumen with saline to remove all air, preparing the ablation catheter by connecting the ablation catheter irrigation line to the 3-way stopcock, connecting the tubing to the 3-way stopcock, connecting the saline spike to a hanging sterile saline bag, and ensuring the saline inlet and saline outlet line stopcocks are in the open position, placing the irrigation pump tubing through a bubble detector and into the pump, and closing the pump door, and the ablation catheter irrigation lumen and tubing system (the ablation catheter may be continuously irrigated (e.g., at a flow rate of 2 mL / min) while it is in the vasculature to avoid blockage of the irrigation conduit and prevent air from entering the ablation catheter) (irrigation may be stopped after the ablation catheter is removed from the body); verifying user-selectable ablation parameters on the generator; plugging the ablation catheter, along with its cable, into the RF generator; and noting the polarity of the connectors.

[0275] The methods described herein may include ablation catheter insertion and ablation energy delivery, which may include one or more of the following steps: with a 0.014 guidewire positioned deep within a first target intercostal vein, advancing the ablation catheter along the guidewire into the intercostal vein; and, once the ablation catheter is inserted into the patient, initiating a saline chase (examples of which are described herein) from the generator (the ablation catheter may be threaded from a peripheral vessel to the desired location with the assistance of fluoroscopy). (The saline infusion rate of the ablation catheter may be adjusted to assist in entry of the device into the target intercostal vein.) may be increased up to a maximum of 50 mL / min), placing the proximal marker at the anterior midline of the vertebrae on the AP view (if possible), and if the azygos vein to the intercostal vein ostia is to the right of the patient's midline, advancing the device so that the proximal radiopaque marker is in the azygos vein, proximal to the intercostal vein ostia and approximately at the patient's midline, and rotating the C-arm to RAO30 (or an appropriate angle that maximizes the projection length between the proximal and distal radiopaque markers) so that the distal marker passes the costovertebral joint. and adjusting if necessary; verifying that valid impedance readings are displayed on the generator for both electrodes (e.g., values ​​in the range of 80-150 Ω in monopolar mode or values ​​in the range of 60-80 Ω in bipolar mode); activating a saline infusion rate of 15-30 ml / min before the start of ablation energy delivery (the recommended saline infusion rate during ablation may be 15 ml / min) (the saline infusion rate may be adjusted to be in the range of 15-30 ml / min after the start of RF delivery); initiating the RF ablation mode algorithm from the generator; monitoring the impedance display on the RF generator before, during, and after RF power delivery; manually terminating power delivery if a sudden increase in impedance is observed during RF delivery that does not exceed a pre-set limit; clinically assessing the situation; and, if necessary, removing the ablation catheter.Inspect for damage; if steam burst or automatic shutoff occurs, discontinue RF and remove the ablation catheter; terminate the saline chase from the RF generator and perform a visual inspection to check for clots, charring, or other catheter malfunctions; verify the saline infusion rate before reinsertion into the patient, flush the port, and resume saline chase upon insertion; replace the ablation catheter if malfunctioning; reposition the ablation catheter and attempt a new RF application (optionally, no more than two 180-second RF applications must be completed at any one target site); if the pump alarms and stops irrigation, immediately remove the catheter from the patient and inspect and re-flush the ablation catheter; and once ablation is complete at the first target intercostal vein (e.g., T11), The method may include one or more of the following steps: withdrawing the guidewire and ablation catheter from the target intercostal vein and holding them in place within the azygos vein access sheath (the ablation catheter saline injection rate may be increased up to 50 cc / min to assist in device withdrawal from the target intercostal vein) (the ablation catheter may be withdrawn for inspection); delivering contrast through the azygos vein access sheath to visualize a second target intercostal vein (e.g., T10); repeating the ablation catheter insertion step and ablation energy delivery step to advance the ablation catheter along the guidewire into the second target intercostal vein and perform ablation; and upon completion of ablation in the second target intercostal vein, withdrawing the ablation catheter into the 9F azygos vein access sheath and delivering contrast through the azygos vein access sheath to obtain fluoroscopic images of the azygos vein tree.

[0276] The methods described herein include device withdrawal, which may include one or more of the following steps: withdrawing the ablation catheter into a 9F azygos vein access sheath and withdrawing it from the patient, terminating the saline trace (which may serve to disconnect the connector cable), inspecting the ablation catheter, withdrawing the azygos vein sheath from the patient and closing the venipuncture, and disposing of the device after use in accordance with hospital, governmental, and / or local government policy.

[0277] Not all of these steps must be performed in any of the methods described herein, including the ablation confirmation tests described herein. And some of these steps may be performed in a different order. It is notable that the procedures described herein seek to target specific nerves or nerve roots, do so from specific target veins, and place ablation elements or members in specific regions within those veins. The access and targeted anatomical regions necessitate specific design requirements. Other treatments targeting various anatomical locations for placement and targeting various target nerves may have very different device design constraints for those approaches, and therefore very different devices that can be used in those treatments. Thus, the present disclosure presents specific reasons for designing specific devices, including the ability to effectively perform the treatments specifically described herein.

[0278] While the above description presents one or more process or apparatus embodiments, it will be understood that other processes or apparatus may be within the scope of the appended claims.

[0279] To the extent that any amendment, characterization, or other assertion previously made with respect to any art, whether prior art or otherwise (in this patent application or in any related patent application or patent, including any parent, sibling, or progeny thereof) may be construed as a disclaimer of any subject matter supported by the present disclosure of this application, Applicant hereby vacates and withdraws such disclaimer. Applicant also respectfully submits that reconsideration of any prior art previously contemplated in any related patent application or patent, including any parent, sibling, or progeny thereof, may be necessary.

[0280] Specific embodiments described herein do not limit any claim, and any claim may encompass a process or apparatus different from the process or apparatus described below, unless otherwise specified. A claim is not limited to an apparatus or process having all of the features of any one apparatus or process described below, or to features common to more than one or all of the apparatus described below, unless otherwise specified. An apparatus or process described below may not be an embodiment of any exclusive rights conferred by the issuance of this patent application. Any subject matter described below to which exclusive rights are not conferred by the issuance of this patent application may be the subject of a separate protective instrument, e.g., a continuing patent application, and the applicant, inventor, or owner does not waive, disclaim, or make available to the public any such subject matter by its disclosure in this document.

[0281] Additional Examples

[0282] A first additional example is a method for characterizing the position of a patient's azygos vein relative to a portion of the patient's spine, the method including the steps of: intravascularly delivering a device into the patient's azygos vein while imaging at least a portion of the patient's spine; and at least one of injecting a radiopaque contrast agent (e.g., a dye) from the device into the patient's vasculature (e.g., into the azygos vein and / or one or more intercostal veins) to visualize the vasculature relative to the position of the spine; or identifying the position of at least a portion of the device relative to the portion of the spine; and characterizing (e.g., qualifying and / or quantifying) the position of the patient's azygos vein relative to the portion of the spine (e.g., relative to the midline of the spine).

[0283] In this first additional embodiment, the imaging may include imaging as an anterior-posterior view.

[0284] This first additional embodiment may further include determining a lateral position of the patient's azygos vein (where the azygos vein intersects with the intercostal veins) relative to the patient's spine. Determining the lateral position of the patient's azygos vein may be performed while imaging the patient's azygos vein. The imaging may include radiographic imaging (e.g., fluoroscopy) after injecting a radiopaque contrast agent (e.g., dye) from the device into the patient's vasculature. Determining the lateral position may be used to determine where to place an ablation catheter relative to the intercostal veins as part of an ablation procedure (optionally ablating the GSN).

[0285] A second additional example is a method that includes assessing the position of a patient's azygos vein to determine whether the azygos vein is centrally located, right-biased (to the right of the patient's center), or left-biased (to the left of the patient's center). Evaluating the position of the patient's azygos vein may be performed while imaging the patient's azygos vein. The imaging may include radiological imaging (e.g., fluoroscopy). The imaging may include imaging as an anterior-posterior view. Evaluating the position may be used to determine where to place an ablation catheter as part of an ablation procedure (optionally intended to ablate the GSN).

[0286] In this second additional embodiment, the evaluating step may be used to determine where to place a radiopaque marker (optionally a proximal radiopaque marker) on an ablation catheter, the ablation catheter including an ablation element distal to the radiopaque marker.

[0287] In this second additional embodiment, the evaluating step is used to determine whether the radiopaque marker should be placed at the venous ostium where the azygos vein meets the intercostal veins or at (approximately including) the midline of the spine.

[0288] In this second additional embodiment, if the evaluating step indicates that the azygos vein is right-biased or centrally located (including near-centrally), the method may include placing a radiopaque marker at the venous ostium where the azygos vein meets the intercostal veins.

[0289] In this second additional embodiment, if the evaluating step indicates that the azygos vein is deviated to the left, the method may include placing a radiopaque marker at (or approximately at) the midline of the spine (as determined, for example, on an anterior-posterior imaging image).

[0290] In this second additional embodiment, the evaluating step may be used to determine where to place an ablation element (eg, one or more electrodes) that is part of an ablation catheter.

[0291] In this second additional embodiment, the method may further include assessing the location of the distal radiopaque marker relative to at least one or more of the vertebrae, the ribs, or a portion of the costovertebral joint. The method may further include retracting the ablation catheter proximally if the assessment indicates that the distal radiopaque marker is located too distally (and thus the ablation element is located too distally). The method may further ensure that the distal radiopaque marker is not distal to the costovertebral joint.

[0292] A third additional embodiment is a method of intravascularly placing an ablation catheter for GSN ablation, the method including placing an ablation catheter in one or both of an intercostal vein (e.g., T9, T10, or T11) and an azygos vein, where the location of the ablation catheter is selected based on a characterized relative position of a portion of the spine and a location in the azygos vein where the azygos vein intersects with the intercostal vein.

[0293] A fourth additional example is a method for characterizing the position of a distal portion of an ablation catheter to facilitate placing at least a portion of the ablation catheter within an intercostal vein, the method including: placing the ablation catheter in an intercostal vein (e.g., a T9, T10, or T11 intercostal vein) of a patient; and determining the location of one or more components of the ablation catheter relative to one or more of a portion of the spine, a rib, or a costovertebral joint while imaging a portion of the patient including the intercostal vein and a portion of the spine.

[0294] A fifth additional embodiment is a method of any claim described herein, the method including the step of accessing the venous vasculature in a patient's jugular or femoral vein with an access introducer sheath (e.g., 12F).

[0295] A sixth additional embodiment is a method of any claim described herein, wherein the method includes delivering a delivery sheath (e.g., a 9F sheath) to the azygos vein (e.g., one or two chest levels above the target intercostal vein).

[0296] A seventh additional embodiment is the method of any claim described herein, wherein the method includes delivering a contrast agent to indicate the location of the azygos vein and one or more intercostal veins while imaging the azygos vein and one or more intercostal veins.

[0297] Any of the additional embodiments may include an imaging step that includes imaging in the anterior-posterior direction (eg, with the C-arm in the AP position).

[0298] Any of the additional embodiments may include positioning the C-arm at a right anterior oblique (RAO) angle.

[0299] Any of the additional embodiments may include positioning the C-arm in a range of 20-70 degrees (eg, 30-60 degrees).

[0300] Any of the additional embodiments may include positioning the C-arm at an angle that maximizes the projected distance between a first location and a second location axially spaced apart on the ablation catheter (e.g., the location of a proximal radiopaque marker and the location of a distal radiopaque marker).

[0301] Any of the additional embodiments may include assessing whether an RO marker (eg, a distal RO marker) is at or proximal to a particular anatomical location (eg, the costovertebral joint).

[0302] In any additional embodiment, if the marker is at or proximal to the particular anatomical location, the method may include continuing the ablation procedure (e.g., ablating tissue). If the marker is not at or proximal to the particular anatomical location, the method may include moving the ablation catheter within the intercostal vein. If the marker is not at or proximal to the particular anatomical location, the method may include generating ablation energy with a proximal ablation element (e.g., a coiled electrode) rather than a distal ablation element (e.g., a coiled electrode).

[0303] An eighth additional embodiment is an ablation catheter sized and configured such that a distal portion of the ablation catheter can be advanced from the azygos vein into a T9, T10, or T11 intercostal vein and adapted to deliver ablation energy, the ablation catheter including an elongate shaft of a length such that the distal portion of the catheter can be positioned within the T9, T10, or T11 intercostal vein, the distal portion including an electrically conductive, flexible ablation element carried on the elongate shaft, the electrically conductive, flexible ablation element (which may include two or more ablation elements) having a length of 5-20 mm, and the distal portion having an outer diameter (at least in the delivery configuration) of 1.5-3 mm.

[0304] A ninth additional example is an ablation catheter sized and configured such that a distal portion of the ablation catheter can be advanced from the azygos vein into a T9, T10, or T11 intercostal vein and adapted to deliver ablation energy, the catheter including an elongate shaft of a length such that the distal portion of the catheter can be positioned within the T9, T10, or T11 intercostal vein, the distal portion including an electrically conductive, flexible ablation element carried on the elongate shaft.

[0305] In this ninth additional embodiment, the ablation element may include a first ablation element and a second ablation element axially spaced apart from one another, the first and second ablation elements being carried on a shaft. The first ablation element may have a coiled configuration, and the second ablation element may have a coiled configuration. The coiled configuration of the first ablation element may be the same as the coiled configuration of the second ablation element in all respects. The coiled configuration of the first ablation element may differ from the coiled configuration of the second ablation element in at least one respect.

[0306] In this ninth additional embodiment, the first ablation element may have a different length than the second ablation element.

[0307] In this ninth additional embodiment, the coil orientation (eg, left-handed or right-handed) of the first ablation element may be different from the second ablation element.

[0308] In this ninth additional embodiment, the pitch of the first ablation element may be different from the pitch of the second ablation element.

[0309] In this ninth additional embodiment, the wire thickness of the first ablation element may be different from the second ablation element.

[0310] In this ninth additional embodiment, the outer diameter of the distal portion at the location of the first ablation element may be different from the outer diameter of the distal portion at the location of the second ablation element.

[0311] In this ninth additional embodiment, the first ablation element and the second ablation element may each have a curvilinear (e.g., circular) or rectilinear (e.g., rectangular) cross-sectional profile.

[0312] In this ninth additional embodiment, the material of the first ablation element and the second ablation element may be a superelastic material, such as Nitinol.

[0313] In this ninth additional embodiment, the first ablation element and the second ablation element may have sufficient flexibility to allow the distal portion to be advanced from the azygos vein into one of the T9, T10, or T11 intercostal veins.

[0314] In this ninth additional embodiment, at least one of the first and second ablation elements may be made from a laser-cut tubular element (eg, a nitinol tube).

[0315] In this ninth additional embodiment, at least one of the first and second ablation elements may comprise a wire mesh or a wire braid.

[0316] In this ninth additional embodiment, at least one of the first and second ablation elements may be a ring electrode having a length of 5 mm or less, optionally around 3 mm.

[0317] In this ninth additional embodiment, the length of each of the first and second ablation elements may be between 1 and 12 mm, optionally between 2 and 12 mm, optionally between 5 and 12 mm, optionally between 6 and 11 mm, optionally between 7 and 10 mm, for example around 8 mm.

[0318] In this ninth additional embodiment, the axial spacing between the first ablation element and the second ablation element may be 0 to 8 mm, such as 0 to 5 mm, such as 0.5 to 5 mm, such as 1 to 4 mm.

[0319] In this ninth additional embodiment, the overall axial length of the ablation element may be between 1 and 25 mm, optionally between 2 and 22 mm, optionally between 5 and 20 mm, optionally between 8 and 20 mm, optionally between 10 and 20 mm, optionally between 10 and 18 mm, optionally preferably between 10 and 15 mm.

[0320] In this ninth additional embodiment, the diameter of the ablation elements (optionally both the first and second ablation elements) may be expandable.

[0321] In this ninth additional embodiment, the ablation element may include a plurality of ablation elements, the first and second of which may be a portion of the entire plurality of ablation elements or may define the entire plurality of ablation elements.

[0322] In this ninth additional embodiment, multiple ablation elements may be configured to be individually energized in a monopolar mode (with a ground pad).

[0323] In this ninth additional embodiment, any two of the plurality of ablation elements may be configured to be energized in a bipolar mode.

[0324] In this ninth additional embodiment, the catheter may include a temperature sensor mounted on the shaft and positioned between the first ablation element and the second ablation element.

[0325] In this ninth additional embodiment, the catheter may further include one or both of a temperature sensor distal to the distal ablation element or a temperature sensor proximal to the proximal ablation element.

[0326] In this ninth additional embodiment, the catheter may include at least one irrigation port in fluid communication with the irrigation lumen, the irrigation lumen being connectable to a fluid source at a proximal portion of the ablation catheter. The ablation catheter may further include a second irrigation port distal to the proximal ablation element.

[0327] In this ninth additional embodiment, the catheter may include one or more irrigation ports located between the distal and proximal ends of the distal ablation member, and optionally between the windings of the coiled distal ablation member.

[0328] In this ninth additional embodiment, the catheter may include one or more irrigation ports located between the distal and proximal ends of the proximal ablation member, and optionally between the windings of the coiled proximal ablation member.

[0329] In this ninth additional embodiment, the catheter may include one or more irrigation ports beneath any of the flexible ablation elements (eg, the distal ablation element and / or the proximal ablation element).

[0330] In this ninth additional embodiment, the catheter may further include a deployable element (optionally expandable) carried on the shaft. The deployable element may be distal to the ablation element and, optionally, distal to the distal ablation element. The deployable element may be expandable, and the shaft may include an inflation port within the expandable element. The deployable element may have a delivery configuration and a deployed configuration having a larger outer diameter than the delivery configuration. The deployable element may have an outer diameter of 3-6 mm, e.g., 4-6 mm, in the deployed configuration. The outer diameter of the deployable element may be equal to or less than 0.2 mm larger than the outer diameter of the shaft in the distal portion. The deployable element may include at least one of a balloon, a bellows member, or a coated stent or coated stent-like device (e.g., a reinforcing member coated with one or more layers of material).

[0331] In this ninth additional embodiment, the ablation catheter may further include a proximal deployable element carried on the shaft proximal to the ablation element, which may be proximal to the proximal ablation element. The proximal deployable element may be inflatable, and the shaft may include an inflation port within the proximal deployable element. The proximal deployable element may have a delivery configuration and a deployed configuration having a larger outer diameter than the delivery configuration. The outer diameter of the deployable element may be 4-10 mm in the deployed configuration and may optionally be larger than the outer diameter of the distal deployable member. The outer diameter of the proximal deployable element may be equal to or less than 0.2 mm larger than the outer diameter of the shaft within the distal portion. The proximal deployable element may include at least one of a balloon, a bellows member, or a coated stent or coated stent-like device (e.g., a reinforcing member coated with one or more layers of material).

[0332] In this ninth additional embodiment, the catheter may include a central deployable element that may include any of the features of the distal or proximal deployable members described herein, including any combination of those features.

[0333] In this ninth additional embodiment, the catheter is configured to perform transvascular ablation of the GSN. The ablation catheter may include a distal section comprising the most distal 7 cm of the ablation catheter. The ablation element may be adapted to create an ablation ranging in length from 5 to 25 mm.

[0334] In this ninth additional embodiment, the distal portion may be adapted to flexibly traverse the curvature (eg, radius of curvature ≧5 mm, angle approximately 120 degrees) from the azygos vein to the T9-T11 intercostal veins.

[0335] In this ninth additional embodiment, the outer diameter of the distal portion is in the range of 1.5 to 3 mm (at least in the delivery state).

[0336] In this ninth additional embodiment, the ablation catheter may further include a guidewire lumen within the elongate shaft.

[0337] In this ninth additional embodiment, the overall length of the ablation element (which may include multiple individual ablation elements) may be between 5 and 20 mm, for example between 10 and 15 mm.

[0338] In this ninth additional embodiment, any of the ablation elements may include one or more of an RF ablation electrode, a coiled wire electrode, a laser cut RF electrode, an RF electrode printed with conductive ink, an RF electrode on an inflatable balloon (e.g., conductive ink, flexible circuit), a conductive membrane RF electrode, an RF electrode on an inflatable cage or mesh, an ultrasonic ablation transducer, an electroporation electrode, a cryoablation element, or a virtual RF electrode.

[0339] In this ninth additional embodiment, the ablation element may be adapted to deliver ablation energy circumferentially (radially symmetrically around the ablation element / circumferentially around the blood vessel).

[0340] In this ninth additional embodiment, the catheter may further include a proximal radiopaque marker located on the shaft at or proximal to the proximal end of the ablation element.

[0341] In this ninth additional embodiment, the catheter may further include a distal radiopaque marker located on the shaft distal to the distal end of the ablation element.

[0342] In this ninth additional embodiment, the catheter may include an axial space between the distal radiopaque marker and the distal end of the ablation element.

[0343] Any of the methods in any of these additional methods may be used with any of the catheters in these additional embodiments. Any of the catheters in these additional embodiments may be used with the methods described herein or in ways not described herein. [Appendix 1] 1. An ablation catheter adapted to ablate a great splanchnic nerve from within an intercostal vein, comprising: an elongate shaft having a length such that at least a portion of a straight distal portion of the elongate shaft can be positioned within a T9, T10, or T11 intercostal vein; a distal conductive flexible and coiled ablation electrode and a proximal conductive flexible and coiled ablation electrode carried on the straight distal portion, The distal conductive flexible and coiled ablation electrode and the proximal conductive flexible and coiled ablation electrode have a combined axial length of 5 to 25 mm and an axial separation between them of 2.0 mm or less; a plurality of distal electrode irrigation ports in a helical configuration disposed between windings of at least a central portion of the distal electrode; a plurality of proximal electrode irrigation ports in a spiral configuration disposed between windings of at least a central portion of the proximal electrode; a plurality of distal irrigation ports distal to the distal electrode, the plurality of distal irrigation ports being axially aligned and equally spaced circumferentially around the linear distal portion; a plurality of central irrigation ports axially between the distal electrode and the proximal electrode, the plurality of central irrigation ports being aligned axially and equally spaced circumferentially around the linear distal portion; an ablation catheter comprising: [Appendix 2] 2. The ablation catheter of claim 1, wherein the plurality of distal irrigation ports consists of three irrigation ports spaced circumferentially at 120 degree intervals around the straight distal section. [Appendix 3] 2. The ablation catheter of claim 1, wherein the plurality of central irrigation ports consists of three irrigation ports spaced circumferentially at 120 degree intervals around the straight distal portion. [Appendix 4] 2. The ablation catheter of claim 1, wherein the plurality of distal electrode irrigation ports are arranged in a spiral pattern having the same pitch as the coiled distal electrode. [Appendix 5] 5. The ablation catheter of claim 4, wherein the plurality of proximal electrode irrigation ports are arranged in a spiral pattern having the same pitch as the coiled proximal electrode. [Appendix 6] 2. The ablation catheter of claim 1, wherein the plurality of proximal electrode irrigation ports are arranged in a spiral pattern having the same pitch as the coiled proximal ablation electrode. [Appendix 7] 2. The ablation catheter of claim 1, wherein the straight distal section has no irrigation ports proximal to the proximal ablation electrode. [Appendix 8] 2. The ablation catheter of claim 1, wherein there are no irrigation ports between the windings at the distal and proximal ends of at least one of the proximal and distal electrodes. [Appendix 9] 2. The ablation catheter of claim 1, wherein the distal and proximal ends of the distal and proximal ablation elements, respectively, have a non-uniform pitch. [Appendix 10] 2. The ablation catheter of claim 1, wherein the plurality of distal irrigation ports are within 2 mm of the distal end of the distal ablation electrode. [Appendix 11] 2. The ablation catheter of claim 1, wherein the plurality of distal electrode irrigation ports, the plurality of proximal electrode irrigation ports, the plurality of distal irrigation ports, and the plurality of central irrigation ports collectively define a plurality of irrigation ports having a combined total area in the range of 1.51e-4 to 1.08e-3 square inches. [Appendix 12] 13. The ablation catheter of claim 12, wherein the diameter of the plurality of irrigation ports is in the range of 0.002 to 0.009 inches. [Appendix 13] 13. The ablation catheter of claim 12, wherein the number of irrigation ports is in the range of 17 to 344. [Appendix 14] 14. The ablation catheter of claim 13, wherein the size and number of the irrigation ports are determined so that the Weber number is in the range of 0.4 to 53 when irrigation fluid is delivered from the irrigation ports at a rate of 15 to 50 ml / min. [Appendix 15] 2. The ablation catheter of claim 1, wherein the distal portion has a distal length of 60 to 70 mm and is sufficiently flexible to be advanced from the azygos vein into an intercostal vein, and the elongate shaft has a central portion proximal to the distal portion, the central portion having a central length of 15 to 25 mm and a central stiffness greater than the distal stiffness of the distal portion. [Appendix 16] 1. An ablation catheter adapted to advance from an azygos vein into an intercostal vein for transvascular ablation of a thoracic splanchnic nerve (particularly ablation of a greater splanchnic nerve or a greater splanchnic nerve root), comprising: an elongate shaft having a length such that at least a portion of a straight distal portion of the elongate shaft can be positioned within a T9, T10, or T11 intercostal vein; a distal conductive flexible and coiled ablation electrode and a proximal conductive flexible and coiled ablation electrode carried on the straight distal portion; Including, the distal conductive flexible and coiled ablation electrode and the proximal conductive flexible and coiled ablation electrode have a combined axial length of 5 to 25 mm; the distal portion has a distal length of 60 to 70 mm and is sufficiently flexible to be advanced from the azygos vein into an intercostal vein; the elongate shaft has a central portion proximal to the distal portion, the central portion having a central length of 15 to 25 mm and a central stiffness greater than a distal stiffness of the distal portion; the elongate shaft has a proximal portion proximal to the central portion, the proximal portion having a length greater than the distal length and greater than the central length, and the proximal portion having a proximal stiffness greater than the central stiffness and greater than the distal stiffness; Ablation catheter. [Appendix 17] 17. The catheter of claim 16, wherein the central portion is directly axially adjacent to the distal portion. [Appendix 18] 18. The catheter of claim 17, wherein the proximal portion is directly axially adjacent to the central portion. [Appendix 19] 17. The catheter of claim 16, wherein the durometer of the distal portion is 50-60D, optionally 55D. [Appendix 20] 17. The catheter of claim 16, wherein the durometer of the central portion is 60-70D, optionally 60-65D. [Appendix 21] 17. The catheter of claim 16, wherein the distal end of the proximal section is at least 50 mm from the distal end of the catheter. [Appendix 22] 17. The catheter of claim 16, wherein the distal end of the proximal portion is 75 to 100 mm from the distal end of the catheter. [Appendix 23] 17. The catheter of claim 16, wherein the proximal portion extends to a proximal end of the elongate shaft. [Appendix 24] 17. The catheter of claim 16, wherein the proximal portion includes a braided reinforcement structure therein. [Appendix 25] 25. The catheter of claim 24, wherein the distal section and the central section do not include a braided reinforcement structure. [Appendix 26] 17. The catheter of claim 16, wherein the proximal portion has a durometer of 70-80D, optionally 70-75D. [Appendix 27] 17. The catheter of claim 16, wherein the distal portion has an outer diameter of 1.5 to 3 mm when outside the sheath. [Appendix 28] 17. The catheter of claim 16, wherein the distal portion has a distal diameter, the central portion has a central diameter, and the proximal portion has a proximal diameter, the distal diameter being smaller than the central diameter, and the central diameter being smaller than the proximal diameter. [Appendix 29] 17. The catheter of claim 16, further comprising a distal tip portion distal to the distal section, the distal tip portion having a length of 5 to 10 mm, and the distal stiffness being greater than the distal tip stiffness of the distal tip portion. [Appendix 30] 1. A computer-executable method adapted to calculate a cumulative volume of fluid delivered to a patient through a catheter, excluding fluid that may not have been delivered through the catheter into the patient's vasculature, comprising: commencing a method of calculating a cumulative volume of fluid delivered from outside a catheter through said catheter into a patient; in response to an exclusion event indicating that the catheter is no longer within the patient, stopping the method of calculating the cumulative fluid volume so that the cumulative volume does not include any volume of fluid that was not delivered into the patient's vasculature; A method comprising: [Appendix 31] 31. The method of claim 30, wherein the exclusion event comprises a manual action that stops the method. [Appendix 32] 31. The method of claim 30, wherein the exclusion event includes an automatic action that stops the method. [Appendix 33] 31. The method of claim 30, wherein the method of calculating the cumulative liquid volume comprises calculating the cumulative volume by multiplying the flow rate by an elapsed time. [Appendix 34] 34. The method of claim 33, wherein the flow rate is determined by multiplying the volume per pulse by the number of pulses per second. [Appendix 35] 31. The method of claim 30, further comprising calculating a cumulative volume of the fluid that has not been delivered into the patient's vasculature if it is determined that the catheter is not within the patient's vasculature. [Appendix 36] 31. The method of claim 30, wherein the exclusion event comprises a measured or calculated impedance value falling outside a range or exceeding a limit threshold. [Appendix 37] 37. The method of claim 36, wherein the exclusion event comprises a measured or calculated impedance greater than 700-900 Ω in monopolar mode. [Appendix 38] 37. The method of claim 36, wherein the exclusion event comprises a measured or calculated impedance greater than 800-3000 Ω (e.g., greater than 900 Ω). [Appendix 39] 37. The method of claim 36, wherein the exclusion event comprises a measured or calculated impedance greater than 300-600 Ω in bipolar mode. [Appendix 40] 37. The method of claim 36, wherein the exclusion event comprises a measured or calculated impedance greater than 900 ohms. [Appendix 41] 31. The method of claim 30, wherein the exclusion event comprises measured or calculated impedance being above an upper threshold or below a lower threshold. [Appendix 42] 42. The method of claim 41, wherein the exclusion event comprises a measured or calculated impedance greater than 900 Ω in monopolar mode. [Appendix 43] 31. The method of claim 30, wherein the method of calculating cumulative liquid volume continues uninterrupted unless the exclusion event occurs. [Appendix 44] 31. The computer-executable method of claim 30, wherein the method is stored in an external energy delivery console of the ablation system. [Appendix 45] 1. A method of delivering ablation energy to ablate tissue surrounding an intercostal vein, comprising: delivering ablative RF energy of a first waveform from a power module to a first electrode, the ablative RF energy having an initial power of 15-50 W; delivering ablative RF energy of a second waveform from the power module to a second electrode, the ablative RF energy having an initial power of 15-50 W; receiving information indicative of at least one of a sensed temperature or a measured impedance; determining whether at least one of the sensed temperature or the measured impedance is equal to or greater than a limit; reducing power of at least one of the first waveform and the second waveform if at least one of the sensed temperature or the measured impedance is equal to or greater than a limit threshold; A method comprising: [Appendix 46] 46. ​​The method of claim 45, wherein if at least one of the sensed temperature or the measured impedance is greater than or equal to a limit threshold and a minimum treatment time has not yet expired, the reducing step includes reducing a power of at least one of the first waveform and the second waveform to a second power that is less than the initial power. [Appendix 47] 47. The method of claim 46, wherein the second power is 5 to 10 W less than the initial power. [Appendix 48] 46. ​​The method of claim 45, wherein if at least one of the sensed temperature or the measured impedance is equal to or greater than a limit threshold and a minimum treatment time has elapsed, the reducing step includes reducing a power of at least one of the first waveform and the second waveform to a second power of 0-1 W. [Appendix 49] 49. The method of any one of claims 45 to 48, wherein the first and second waveforms are multiplexed. [Appendix 50] 50. The method of any one of appendix 45 to 49, wherein the first and second waveforms are asynchronous. [Appendix 51] 51. The method of any one of claims 45 to 50, wherein the step of delivering from the power module to the first electrode comprises delivering ablative RF energy of a first waveform from the power module to the first electrode, the ablative RF energy having an initial power of 25 W. [Appendix 52] 52. The method of claim 51, wherein the step of delivering from a power module to a second electrode comprises delivering ablative RF energy of a first waveform from a power module to the second electrode, the ablative RF energy having an initial power of 25 W. [Appendix 53] 53. The method of any one of appendices 45 to 52, wherein the first and second waveforms are alternating waveforms that alternate between ablation and non-ablative power amplitudes. [Appendix 54] 54. The method of claim 53, wherein the non-ablative power amplitude is in the range of 0 to 1 W. [Appendix 55] 55. The method of any one of appendices 45 to 54, wherein the determining step includes determining whether the sensed temperature is 40 to 95°C or higher (optionally 90°C or higher). [Appendix 56] 56. The method of claim 55, wherein the receiving step includes receiving information from a temperature sensor associated with the first electrode. [Appendix 57] 57. The method of any one of claims 55 to 56, wherein the receiving step includes receiving information from a second temperature sensor associated with the second electrode. [Appendix 58] 56. The method of any one of appendixes 45 to 55, wherein the determining step includes determining whether the measured impedance is greater than or equal to 200-500 Ω (optionally greater than or equal to 500 Ω). [Appendix 59] 59. The method of any one of appendixes 45-58, wherein reducing the power of at least one of the first waveform and the second waveform comprises reducing the power of at least one of the first waveform and the second waveform to a power of 10-30 W (optionally 20 W). [Appendix 60] 59. The method of any one of claims 45 to 58, wherein reducing the power of at least one of the first waveform and the second waveform comprises reducing the power of at least one of the first waveform and the second waveform by a power decrement of 1 to 30 W (optionally 5 to 10 W). [Appendix 61] 59. The method of any one of appendixes 45 to 58, wherein the step of reducing the power of at least one of the first waveform and the second waveform includes the step of reducing the power of at least one of the first waveform and the second waveform. [Appendix 62] 62. The method of any one of appendixes 45 to 61, wherein the pulse width of at least one of the first and second waveforms is in the range of 0.5 to 4 seconds. [Appendix 63] 63. The method of any one of appendixes 45 to 62, wherein the power of the first waveform is reduced when the sensed temperature corresponding to the first electrode is equal to or greater than the limit, and the power of the second waveform is reduced when the sensed temperature corresponding to the second electrode is equal to or greater than the limit. [Appendix 64] 64. The method of any one of clauses 45-63, wherein the delivering step is carried out for at least 60 seconds. [Appendix 65] 65. The method of any one of claims 45 to 64, wherein the delivering step is performed at a default setting over a period of 30 to 180 seconds. [Appendix 66] 66. The method of any one of claims 45 to 65, further comprising delivering irrigation fluid to the ablation catheter at a flow rate in the range of 10 to 30 ml / min. [Appendix 67] 1. A system for ablating the greater splanchnic nerve from within an intercostal vein, comprising: 1. An ablation catheter comprising: an elongate shaft having a length such that at least a portion of a straight distal portion of the elongate shaft can be positioned within a T9, T10, or T11 intercostal vein; a distal conductive flexible and coiled ablation electrode and a proximal conductive flexible and coiled ablation electrode carried on the straight distal portion, The distal conductive flexible and coiled ablation electrode and the proximal conductive flexible and coiled ablation electrode have a combined axial length of 5 to 25 mm and an axial separation between them of 2.0 mm or less; a plurality of distal electrode irrigation ports in a helical configuration disposed between windings of at least a central portion of the distal electrode; a plurality of proximal electrode irrigation ports in a spiral configuration disposed between windings of at least a central portion of the proximal electrode; a plurality of distal irrigation ports distal to the distal electrode, the plurality of distal irrigation ports being axially aligned and equally spaced circumferentially around the linear distal portion; a plurality of central irrigation ports axially between the distal electrode and the proximal electrode, the plurality of central irrigation ports being aligned axially and equally spaced circumferentially around the linear distal portion; the ablation catheter comprising: an external device or system adapted to be coupled with the ablation catheter to establish operable communication with the ablation catheter, a power output module adapted to deliver ablative RF energy of a first waveform having an initial power of 15 to 50 W and ablative RF energy of a second waveform having an initial power of 15 to 50 W; a module adapted to receive information indicative of at least one of a sensed temperature or a measured impedance, determine whether at least one of the sensed temperature or the measured impedance is above a limit, and cause the power output module to reduce power of at least one of the first waveform and the second waveform if at least one of the sensed temperature or the measured impedance is above a limit threshold; the external device or system including: A system including: [Appendix 68] 68. The system of claim 67, wherein the module includes at least one of a limit temperature module or a limit impedance module. [Appendix 69] 68. The system of claim 67, wherein the module is adapted to cause the power output module to reduce a power of at least one of the first waveform and the second waveform to a second power less than the initial power when at least one of the sensed temperature or the measured impedance is equal to or greater than a limit threshold and a minimum treatment time has not yet expired. [Appendix 70] 70. The system of claim 69, wherein the second power is 5 to 10 W less than the initial power. [Appendix 71] 68. The system of claim 67, wherein the module is adapted to cause the power output module to reduce a power of at least one of the first waveform and the second waveform to a second power of 0-1 W when at least one of the sensed temperature or the measured impedance is equal to or greater than a limit threshold and a minimum treatment time has expired. [Appendix 72] 68. The system of claim 67, wherein the power output module is adapted to deliver asynchronous first and second waveforms. [Appendix 73] 68. The system of claim 67, wherein the power output module is adapted to deliver ablative RF energy of the first waveform having an initial power of 25 W and ablative RF energy of the second waveform having an initial power of 25 W. [Appendix 74] 68. The system of claim 67, wherein the module is adapted to determine whether the sensed temperature is 40-95°C or greater (optionally 90°C or greater). [Appendix 75] 68. The system of claim 67, wherein the module is adapted to determine whether the measured impedance is greater than 200-500 Ω (optionally greater than 500 Ω). [Appendix 76] 68. The system of claim 67, wherein the power output module is adapted by a default system to deliver the ablation energy for 30 to 180 seconds.

Claims

[Claim 1] 1. An ablation catheter adapted to ablate a great splanchnic nerve from within an intercostal vein, comprising: an elongate shaft having a length such that at least a portion of a straight distal portion of the elongate shaft can be positioned within a T9, T10, or T11 intercostal vein; a distal conductive flexible and coiled ablation electrode and a proximal conductive flexible and coiled ablation electrode carried on the straight distal portion, the distal conductive flexible and coiled ablation electrode and the proximal conductive flexible and coiled ablation electrode having a combined axial length of 5 to 25 mm and an axial separation therebetween of 2.0 mm or less; a plurality of distal electrode irrigation ports in a helical configuration disposed between windings of at least a central portion of the distal conductive flexible coiled ablation electrode; a plurality of proximal electrode irrigation ports in a helical configuration disposed between windings of at least a central portion of the proximal conductive flexible coiled ablation electrode; a plurality of distal irrigation ports distal to the distal conductive flexible coiled ablation electrode, the plurality of distal irrigation ports being axially aligned and equally spaced circumferentially around the straight distal portion; a plurality of central irrigation ports axially between the distal conductive flexible and coiled ablation electrode and the proximal conductive flexible and coiled ablation electrode, the plurality of central irrigation ports being axially aligned and equally spaced circumferentially around the straight distal portion; an ablation catheter comprising:

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