Method and device for endovascular ablation of visceral nerves

Abstract

Systems, devices, and methods for transvascular ablation of target tissue. In some examples, the devices and methods may be used for visceral nerve ablation to increase visceral venous blood volume to treat at least one of heart failure and hypertension. For example, the devices disclosed herein may be advanced in an intravascular manner to a target vessel in a thoracic visceral nerve (TSN) region, such as a visceral major nerve (GSN) or a TSN nerve root. Also disclosed are methods of treating heart failure, such as HFpEF, by endovascularly ablating thoracic visceral nerves to increase vein volume and reduce lung blood pressure.

Description

[0001] This application is a divisional application of the international application filed on January 19, 2021, with international application number PCT / US2021 / 014001, national application number 202180009584.7, entitled "Method and apparatus for endovascular ablation of visceral nerves", which has entered the Chinese national phase.

[0002] By incorporating references This application claims priority to U.S. Provisional Application No. 62 / 962,627, filed January 17, 2020, and U.S. Provisional Application No. 63 / 086,516, filed October 1, 2020, the disclosures of which are incorporated herein by reference in their entirety for all purposes.

[0003] All publications and patent applications mentioned in this specification are incorporated herein by reference in a manner similar to each individual publication or patent application being specifically and individually indicated to be incorporated by reference.

[0004] This invention relates to U.S. Provisional Application No. 62 / 864,093, filed June 20, 2019; U.S. Provisional Application No. 62 / 881,251, filed July 31, 2019; U.S. Provisional Application No. 62 / 962,627, filed January 17, 2020; U.S. Publication Nos. US2019 / 0175912 and US2019 / 0183569; and U.S. Patent No. 10,376,308. The publications of 10,207,110, 16 / 510,503, 62 / 836,720, 62 / 837,090, 62 / 864,093, PCT / US2019 / 15400, PCT / US2020 / 038934 and PCT publications WO2018 / 023132, WO2019 / 118976 and WO / 2020 / 257763 are incorporated herein by reference in their entirety for all purposes. Background Technology

[0005] Heart failure (HF) is a medical condition that occurs when the heart is unable to pump enough blood to sustain the body's organs. HF is a serious condition affecting millions of patients in the United States and around the world.

[0006] A common measure of heart health is the left ventricular ejection fraction (LVEF), or ejection fraction. By definition, the volume of blood in the ventricles immediately preceding systole is called the end-diastolic volume (EDV). Similarly, the volume of blood remaining in the ventricles at the end of systole is called the end-systolic volume (ESV). The difference between EDV and ESV is stroke volume (SV). SV describes the amount of blood ejected from the right and left ventricles with each heartbeat. Ejection fraction (EF) is the fraction of EDV ejected with each beat; that is, it is SV divided by EDV. Cardiac output (CO) is defined as the amount of blood pumped by each ventricle of the heart per minute. CO equals SV multiplied by heart rate (HR).

[0007] Cardiomyopathy (in which the heart muscle is weakened, stretched, or exhibits other structural problems) can be further classified into systolic and diastolic dysfunctions based on ventricular ejection fraction.

[0008] While many pharmacological therapies have successfully targeted systolic dysfunction and HFrEF, promising treatments have not yet been identified for the large number of patients with diastolic dysfunction and HFpEF. The clinical course of patients with HFrEF and HFpEF is significant for relapses of acute decompensated heart failure (ADHF) accompanied by symptoms such as dyspnea, decreased exercise capacity, and peripheral edema. Relapsed hospitalizations for ADHF utilize a large portion of existing healthcare resources and can continue to incur substantial costs.

[0009] Despite a growing understanding of the pathophysiology of heart failure (HF), modern medicine has so far failed to develop new therapies for the chronic management of HF or recurrent acute depressive heart failure (ADHF). Over the past few decades, strategies for the management and prevention of ADHF have focused, and continue to focus, on the classic paradigm that salt and fluid retention are the cause of intravascular fluid dilation and cardiac decompensation.

[0010] Therefore, there remains a need for safe and effective improved therapies for patients with heart failure, as well as devices and systems suitable for and configured to perform these therapies. Summary of the Invention

[0011] This invention relates to methods, apparatus, and approaches for ablating thoracic splanchnic nerves or thoracic splanchnic nerve roots. Ablation can be performed to treat at least one of hypertension and heart failure, but general methods can also be used for other treatments. For example, the methods described herein can be used to treat pain, or even generally benefit a subject by reducing the amount of blood draining from the visceral bed into the central thoracic vein.

[0012] The treatment described in this article can be achieved by increasing visceral volume. The therapy typically involves ablation of the patient's preganglionic thoracic splanchnic nerves or thoracic splanchnic nerve roots to increase visceral volume, thereby treating at least one of hypertension and heart failure.

[0013] The methods described in this article describe the ablation of thoracic splanchnic nerves, such as the greater splanchnic nerve or the greater splanchnic nerve root. While the methods described in this article provide specific examples of targeting the greater splanchnic nerve or the greater splanchnic nerve root, they can alternatively or additionally ablate other thoracic splanchnic nerves (e.g., the lesser splanchnic nerve, the smallest splanchnic nerve) to perform one or more of the treatments described in this article.

[0014] One aspect of the invention is a method for ablating tissue, wherein a medical device is positioned intravascularly near a target tissue, and the medical device is used to ablate the tissue and create damage. Another aspect of the invention is a method for ablating tissue, wherein a medical device is positioned intravascularly within one or more target blood vessels, and the medical device is used to ablate the tissue and create damage. Therefore, the methods 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, wherein the target tissue is relatively close to a target region within the one or more blood vessels. Any method steps described herein (including, for example, but not limited to, those in the claims or specification portions) may be incorporated into any other method of use used herein, unless expressly indicated to the contrary herein.

[0015] One aspect of the invention is a method for ablating a major splanchnic nerve or a major splanchnic nerve root to increase splanchnic venous blood volume and / or venous compliance, the method comprising advancing a medical device into a first blood vessel, advancing the medical device at least partially into a second blood vessel, and delivering ablation energy from the medical device to induce damage in tissue surrounding the first blood vessel.

[0016] In some implementations, the first vessel is the azygos vein, and the second vessel is the intercostal vein. The intercostal vein can be one of the three lowest intercostal veins. The intercostal vein can be the T9, T10, or T11 intercostal vein.

[0017] The method may include positioning the distal end of the ablation element in the second blood vessel and at a distance of no more than 30 mm (e.g., 20 mm, 15 mm, 12 mm) from the junction between the first and second blood vessels when delivering energy from the ablation element.

[0018] The method may include placing the proximal portion of the ablation element in a second blood vessel while delivering energy.

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

[0020] In some implementations, aligning or positioning the ablation element relative to a bony landmark (such as a costovertebral joint) involves using medical imaging (such as fluorescence fluoroscopy) to visualize the bony landmark.

[0021] In some implementations, using medical imaging (such as fluorescence fluoroscopy) to observe bony landmarks involves orienting the medical imaging viewpoint at an anterior oblique angle ranging from 25º to 65º from the AP toward the patient side where the target nerve is located (e.g., within the range of 30º to 60º, or within the range of 35º to 55º).

[0022] In some implementations, medical imaging (such as fluorescence fluoroscopy) is used to orient the medical imaging viewpoint by observing bony landmarks, including a line approximately perpendicular to the patient's first blood vessel (e.g., azygos vein) and a bony landmark (e.g., costovertebral joint).

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

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

[0025] The method may include positioning the entire ablation element in the second blood vessel, and the method may further include positioning less than the entire length of the ablation element in the second blood vessel.

[0026] The method may include performing an ablation procedure within one or more target vessels (e.g., intercostal veins or azygos veins). The ablation method described herein may also be performed in a second vessel.

[0027] The method may include performing ablation confirmation tests, such as any of the tests described herein. If desired or required, the ablation element may be repositioned into a second target vessel, which may be the azygos vein or a different intercostal vein.

[0028] The method may further include delivering stimulation energy to a first stimulation electrode and a second stimulation electrode carried by a medical device before, during, and / or after the delivery of ablation energy. Delivering stimulation energy can help determine whether the ablation element is at its target location within the intercostal vein and / or whether the ablation procedure is effective.

[0029] One aspect of the invention is a method comprising: delivering an ablation catheter including an energy delivery element (or component) through a patient's venous system; positioning the energy delivery element at least partially (optionally, completely) medial to a vein selected from the T9, T10, and T11 intercostal veins; and delivering ablation energy from the energy delivery element to produce a continuous lesion having a depth of at least 5 mm and a length from 10 mm to 25 mm. The continuous lesion and its parameters can be formed by selecting or choosing certain energy delivery parameters that will produce the lesion. In some embodiments, the lesion may extend along the intercostal vein from the sinus ostium of the azygos vein to a maximum of 20 mm. Any other method steps described in the context of other methods may be performed using this exemplary method.

[0030] In some alternative approaches described herein, multiple ablations (i.e., from ablation energy on to energy ablation off) can be performed within a single target vessel (e.g., intercostal vein) to produce a total damage resulting from two or more lesions formed by multiple ablations. The total damage formed from multiple lesions can possess any of the characteristics of other lesions described herein. For example, the total damage can be continuous (formed by the connection of multiple lesions produced during different ablation periods), can be up to 20 mm in length, can be circumferential (or not circumferential), etc. After the first ablation, the ablation device can be moved within the same vessel and produce a second lesion, which may or may not overlap with the first lesion. This can be repeated multiple times as needed. Even with multiple ablations performed in a single vessel, any stimulation or testing steps described herein can be performed before, during, or after any ablation step.

[0031] One aspect of the invention is a method for positioning an ablation catheter in the T9, T10, or T11 intercostal veins for ablation of the greater visceral nerve (GSN), the method comprising: imaging a portion of a subject including at least one of the T9, T10, or T11 intercostal veins and a portion of the subject's spine; positioning a distal segment of the ablation catheter in the T9, T10, or T11 intercostal veins; and positioning a radiopaque marker of the ablation catheter at a location based on the position of the radiopaque marker relative to anatomical landmarks, such as a portion of the spine, a rib, a costovertebral joint, the azygos vein, or one or more sinus ostia between the azygos vein and the T9, T10, or T11 intercostal veins. The method may further include delivering energy from an ablation element of the ablation catheter to ablate tissue.

[0032] One aspect of the invention is a method comprising characterizing the relative position of a patient's azygos vein to determine whether the azygos vein is centrally or substantially centrally located, right-biased (to the right of the patient's center), or left-biased (to the left of the patient's center). This characterization step can occur while observing specific portions of the patient's anatomy and begins from a specific viewpoint that allows for precise characterization. The method may also include locating an ablation catheter based on this characterization step.

[0033] One aspect of the invention is a method for characterizing the position of the azygos vein relative to a portion of the spine of a human patient, the method comprising: imaging at least a portion of the patient's spine and vascular system, particularly the azygos vein and / or one or more intercostal veins, using an imaging device, particularly a radiographic imaging device that injects a radiopaque contrast agent into the patient's vascular system; or imaging at least one radiopaque device located in the azygos vein and / or one or more intercostal veins relative to a portion of the spine using an imaging device, particularly a radiographic imaging device, thereby characterizing the position of the patient's azygos vein relative to the midline of the spine, the radiopaque device optionally including a radiopaque portion of a guidewire; and determining, based on one or more images generated by the imaging device, whether the azygos vein is centered, left-biased, or right-biased relative to the midline of the vertebrae. This aspect may also include a method for determining the appropriate location where a catheter should be inserted into the vascular system of a human patient, particularly to allow ablation of the greater splanchnic nerve or the greater splanchnic nerve root, the method comprising determining, based on the determination that the azygos vein is centered, left-biased, or right-biased relative to the midline of the vertebrae, where to place an ablation element for transvascular ablation, particularly any ablation catheter herein.

[0034] This aspect may also include: determining, based on the determination that the azygos vein is centered, left-biased, or right-biased relative to the midline of the vertebra, where to place a radiopaque marker carried by the distal segment of the ablation catheter, optionally, positioning a proximal radiopaque marker proximal to any ablation element carried by the same distal segment.

[0035] One aspect of the invention is a method for determining the proper positioning of a catheter inserted into the vascular system of a human patient, the catheter optionally being a catheter according to any of the claims or disclosures herein, wherein the catheter includes an elongated shaft having a distal segment carrying one or more ablation elements and a proximal radiopaque marker, wherein the distal segment of the elongated shaft is positioned in the T9, T10, or T11 intercostal vein; wherein the method includes: determining whether the azygos vein is centered, left-biased, or right-biased relative to the midline of the vertebra; assessing the position of the proximal radiopaque marker relative to the midline of the vertebra; and verifying whether the catheter is properly positioned relative to the patient's anatomical landmarks, wherein the verification includes: considering the catheter properly positioned when one of the following occurs: if the azygos vein is right-biased, the proximal radiopaque marker is placed at the sinus opening of the intercostal vein and to the right of the midline of the vertebra; or if the azygos vein is centered or left-biased, the proximal radiopaque marker is aligned with the midline of the vertebra.

[0036] In any aspect of the method described herein, the proximal radiopaque marker can be carried by the distal segment and can be positioned proximally to all ablation elements. The proximal radiopaque marker can be located directly proximally to the ablation element or directly proximally to the nearest side of the ablation element carried by the distal segment of the catheter.

[0037] In any aspect of the method herein, the catheter may include a distal radiopaque marker positioned distal to all ablation elements, and the verification step further includes: assessing the position of the distal radiopaque marker relative to the patient's costovertebral joints and / or ribs, confirming that the distal radiopaque marker is spaced at least a predetermined threshold distance from the costovertebral joints and / or ribs. The distal radiopaque marker may be positioned directly distal to the ablation element, or directly distal to the distal end of the ablation element carried by the distal region of the catheter, and the confirmation includes confirming that the distal radiopaque marker is at least 3 mm, preferably at least 5 mm, from the costovertebral joint.

[0038] In any aspect of the methods described herein, verification may include considering the catheter not properly positioned if none of the following occurs: if the azygos vein is right-biased, the proximal radiopaque marker is placed at the sinus opening of the intercostal vein and to the right of the midline of the vertebra; if the azygos vein is centrally located or left-biased, the proximal radiopaque marker is aligned with the midline of the vertebra.

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

[0040] In any aspect of the method herein, the step of determining whether the azygos vein is centered, left-biased, or right-biased relative to the midline of the vertebrae may include: imaging at least a portion of the patient’s spine and vascular system, particularly the azygos vein and / or one or more intercostal veins, using an imaging device, particularly a radiographic imaging device that injects a radiopaque contrast agent into the patient’s vascular system; or imaging at least one radiopaque device located in the azygos vein and / or one or more intercostal veins relative to a portion of the spine, thereby characterizing the position of the patient’s azygos vein relative to the midline of the spine, said radiopaque device optionally including a radiopaque portion of a guidewire.

[0041] In any aspect of the method described herein, the step of assessing the position of the proximal radiopaque marker relative to the midline of the vertebra may include imaging at least a portion of the duct including the proximal radiopaque marker using an imaging device, particularly a radiographic imaging device.

[0042] In any aspect of the method described herein, the step of assessing the position of the distal radiopaque marker relative to the costovertebral joint may include imaging at least a portion of the duct including the distal radiopaque marker using an imaging device, particularly a radiographic imaging device.

[0043] One aspect of the invention is a method for determining the proper positioning of a catheter inserted into the vascular system of a human patient, optionally as claimed in any of the claims or disclosures herein, wherein the catheter includes an elongated shaft having a distal segment carrying one or more ablation elements and a distal radiopaque marker, wherein the distal segment of the elongated shaft is located in the T9, T10, or T11 intercostal vein; wherein the method includes: determining the position of the distal radiopaque marker relative to the costovertebral joint of the patient; verifying whether the catheter is properly positioned relative to the anatomical landmarks of the patient, wherein the verification includes: considering the catheter properly positioned when the distal radiopaque marker is spaced from the costovertebral joint by at least a predetermined threshold distance. The distal radiopaque marker may be positioned directly distal to the ablation element, or directly distal to the distal end of the ablation element carried by the distal segment of the catheter, and wherein the predetermined threshold distance is at least 3 mm, preferably at least 5 mm.

[0044] In this respect, if it has been verified that the catheter is not properly positioned, the method may further include adjusting the position of the catheter by further moving the distal radiopaque marker away from the costovertebral joint.

[0045] In this respect, the step of determining the position 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 vascular system, particularly the azygos vein and / or one or more intercostal veins, using an imaging device, particularly a radiographic imaging device that injects radiopaque contrast agent into the patient's vascular system; or imaging at least one radiopaque device located in the azygos vein and / or one or more intercostal veins relative to a portion of the spine, thereby characterizing the position of the patient's azygos vein relative to the midline of the spine, the radiopaque device optionally including a radiopaque portion of a guidewire; and imaging at least a portion of a catheter including the distal radiopaque marker using an imaging device, particularly a radiographic imaging device.

[0046] One aspect of the invention is an ablation catheter for transvascular ablation of thoracic splanchnic nerves, particularly for ablation of the greater splanchnic nerve or the greater splanchnic nerve root, the ablation catheter comprising: an elongated shaft having a length such that a distal segment of the elongated shaft can be positioned in the T9, T10, or T11 intercostal vein; a proximal conductive flexible ablation element and a distal conductive flexible ablation element carried in the distal segment of the elongated shaft, the length from the distal end of the distal ablation element to the proximal end of the proximal ablation element being 10 mm-25 mm.

[0047] In this respect, the distal section of the slender shaft can have an outer diameter of 1.5 mm to 3 mm.

[0048] In this respect, there may be an axial gap of 0.1 mm to 5 mm between the proximal ablation element and the distal ablation element, for example, 0.1 mm to 3 mm, 0.1 mm to 2 mm, or 5 mm to 1 mm.

[0049] In this respect, distal ablation elements and proximal ablation elements can be electrodes.

[0050] In this respect, the distal ablation element and the proximal ablation element may each have the same length.

[0051] In this respect, distal ablation elements and proximal ablation elements can each have different lengths.

[0052] In this respect, the distal ablation element and the proximal ablation element may each have a length of 5 mm to 12 mm, for example, 6 mm to 10 mm, for example, 7 mm to 9 mm, for example, any length within any of these ranges.

[0053] In this respect, the distal ablation element may have a helical configuration, and the proximal ablation element may also have a helical configuration. The helical configurations of the distal and proximal ablation elements may be identical. The helical configurations of the distal and proximal ablation elements may have one or more different characteristics, such as one or more of the following: coil orientation (e.g., left-hand versus right-hand), pitch, or thickness.

[0054] In this respect, both the distal ablation element and the proximal ablation element can have a curved cross-section configuration.

[0055] In this respect, both the distal ablation element and the proximal ablation element can have a linear cross-section configuration.

[0056] In this respect, distal and proximal ablation elements can be made of hyperelastic materials such as nitinol.

[0057] In this respect, distal and proximal ablation elements can be flexible and sized to allow the distal segment to be advanced from the azygos vein to one of the T9, T10, or T11 intercostal veins.

[0058] In this respect, the distal ablation element and the proximal ablation element can be attached to the axis at the distal region and the proximal region, respectively, rather than being attached to the axis between the distal region and the proximal region.

[0059] In this respect, the catheter may also 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 0 mm to 5 mm, optionally 0 mm to 3 mm, or 0 mm to 2 mm distal to the distal end of the distal ablation element. The radiopaque marker may also be positioned proximal to the proximal end of the proximal ablation element. The radiopaque marker may be 0 mm to 5 mm, optionally 0 mm to 3 mm, or 0 mm to 2 mm proximal to the distal end of the distal ablation element.

[0060] In this respect, neither the distal ablation element nor the proximal ablation element was configured to expand to an expanded configuration.

[0061] In this respect, the distal ablation element and the proximal ablation element each have the same or substantially the same operating configuration as the delivery configuration.

[0062] In this respect, the distal ablation element and the proximal ablation element each have the same or substantially the same outer diameter in the operating state as in the delivery state.

[0063] In this respect, the distal ablation element and the proximal ablation element can each have an expansion configuration different from the delivery configuration.

[0064] In this respect, the catheter may also include a temperature sensor carried by a shaft. The temperature sensor may be positioned distal to the distal end of the distal ablation element. The temperature sensor may be positioned proximal to the proximal end of the proximal ablation element. The catheter may include a second temperature sensor positioned distal to the distal end of the distal ablation element and proximal to the proximal end of the proximal ablation element.

[0065] In this respect, the catheter may further include one or more infusion ports in fluid communication with an infusion lumen, which is connectable to a fluid source in the proximal region of the ablation catheter. One of the one or more infusion ports may be axially located between the distal ablation electrode and the proximal ablation electrode. Optionally, none of the one or more infusion ports may be radially arranged below the ablation element structure. The one or more infusion ports may be arranged between the helical windings of the distal and proximal ablation electrodes. In a side view, the infusion ports may be arranged between each pair of adjacent helical segments of the distal and proximal ablation elements.

[0066] In this respect, the distal ablation element and the proximal ablation element can be electrically configured to be energized independently in unipolar mode.

[0067] In this respect, the distal ablation element and the proximal ablation element can be electrically configured to be energized in bipolar mode.

[0068] In this respect, the distal segment can be no more than 7 cm from the distal end of the ablation catheter.

[0069] In this respect, distal and proximal ablation elements can be sized and adapted to produce continuous ablation in lengths ranging from 5 mm to 25 mm, for example, 10 to 25 mm, or 15 to 20 mm.

[0070] In this respect, the distal segment can be adapted to flexibly pass through the bends from the azygos vein to the T9, T10 or T11 intercostal veins.

[0071] In this respect, the catheter may also include a guidewire lumen within an elongated shaft and have a distal port at the distal end of the catheter.

[0072] In this respect, the distal ablation element and the proximal ablation element may each include one or more of the following: 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 expandable balloon (e.g., conductive ink, flexible circuit), a conductive film RF electrode, an RF electrode on an expandable cage or mesh, an ultrasonic ablation transducer, an electroporation electrode, a cryoablation element, or a virtual RF electrode.

[0073] In this respect, distal ablation elements and proximal ablation elements can each be adapted and configured to deliver ablation energy circumferentially to produce a ring of damage.

[0074] One aspect of the invention is an ablation catheter for transvascular ablation of thoracic splanchnic nerves, particularly for ablation of the greater splanchnic nerve or the greater splanchnic nerve root, said catheter comprising: an elongated shaft of such length that a distal segment of the elongated shaft can be positioned in the T9, T10, or T11 intercostal vein; a conductive flexible ablation element carried by the distal segment of the elongated shaft, the ablation element having a length of 10 mm to 25 mm; and a radiopaque marker carried by the elongated shaft.

[0075] In this respect, the distal section of the slender shaft can have an outer diameter of 1.5 mm to 3 mm.

[0076] In this respect, the radiopaque marker carried by the elongated shaft can be arranged at a distance of 0 mm to 5 mm from the end of the ablation element, for example, 0 to 4 mm, 0 to 3 mm, or 0 to 2 mm. This end can be the distal end of the ablation element. This end can be the distal end of the distal ablation electrode, and the ablation element can also include a proximal ablation electrode axially spaced from the distal ablation electrode.

[0077] In this respect, the end can be the proximal end of the ablation element.

[0078] In this respect, the catheter may also include a second radiopaque marker carried by an elongated shaft and arranged at a distance of 0 mm to 5 mm (e.g., 0 to 4 mm, 0 to 3 mm, or 0-2 mm from the second end of the ablation element).

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

[0080] In this respect, the radiopaque marker can be arranged at a distance of 0 mm to 3 mm from the end of the ablation element, optionally 1 mm.

[0081] In this respect, the ablation element may include a distal ablation electrode axially spaced from the proximal ablation electrode. The distal and proximal ablation electrodes may each have a length, wherein the lengths are the same or different. The distal and proximal ablation electrodes may each have a length of 5 mm to 12 mm. The distal and proximal ablation electrodes may be axially spaced from 0.1 mm to 5 mm, for example, from 0.1 mm to 3 mm, and optionally from 0.5 mm to 1 mm. In this respect, the distal and proximal ablation elements may be any of the distal and proximal ablation elements described herein, such as a coiled element. In this respect, the cross-sectional outer profile of the distal ablation electrode may differ from that of the proximal ablation electrode. The distal and proximal ablation electrodes may be made of a hyperelastic material (such as nitinol). The distal and proximal ablation electrodes can be flexible enough to allow the distal region to be advanced from the azygos vein to one of the T9, T10, or T11 intercostal veins.

[0082] In this respect, the ablation element may not be configured to expand to an expanded configuration.

[0083] In this respect, the ablation element may have the same or substantially the same operating configuration as the delivery configuration.

[0084] In this respect, the distal segment can have a linear static configuration.

[0085] In this respect, the ablation element may have the same or substantially the same outer diameter in the operating state as it does in the delivery state.

[0086] In this respect, the catheter may also include one or more temperature sensors carried by a shaft. The temperature sensor may be positioned distal to the ablation element. The temperature sensor may be positioned proximal to the ablation element. The catheter may also include a second temperature sensor, which may be positioned distal to or near the ablation element, or proximal to the ablation element.

[0087] In this respect, the catheter may include one or more infusion ports in fluid communication with an infusion lumen, which is connectable to a fluid source in a proximal region of the ablation catheter, the infusion lumen including any of the one or more infusion ports described herein. One of the one or more infusion ports may be axially located between a distal ablation electrode and a proximal ablation electrode. Optionally, none of the one or more infusion ports may be radially arranged below the ablation element structure. The one or more infusion ports may be arranged between the windings of the distal ablation electrode and the proximal ablation electrode, and none of the one or more infusion ports may be radially arranged below the ablation element structure. In a side view, the infusion ports may be arranged between adjacent pairs of ablation element helical segments.

[0088] In this respect, the ablation element may include a first ablation element and a second ablation element, each of which may be electrically configured to be energized independently in a unipolar mode.

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

[0090] In this respect, the distal segment can be no more than 7 cm from the distal end of the ablation catheter.

[0091] In this respect, ablation elements can be adapted to produce ablation lengths ranging from 10 to 25 mm, for example, 15 to 20 mm.

[0092] In this respect, the distal segment can be adapted to flexibly pass through the bends from the azygos vein to the T9, T10 or T11 intercostal veins.

[0093] In this respect, the catheter may also include a guidewire lumen within an elongated shaft and have a distal port at the distal end of the catheter.

[0094] In this respect, ablation elements may include one or more of the following: RF ablation electrodes, coiled wire electrodes, laser-cut RF electrodes, RF electrodes printed with conductive ink, RF electrodes on expandable balloons (e.g., conductive ink, flexible circuits), conductive film RF electrodes, RF electrodes on expandable cages or nets, ultrasonic ablation transducers, electroporation electrodes, cryoablation elements, or virtual RF electrodes.

[0095] In this respect, the ablation element can be adapted and configured to deliver ablation energy circumferentially to produce a ring of damage.

[0096] One aspect of the invention is an ablation catheter for ablating a major visceral nerve, comprising: an elongated shaft; a conductive flexible ablation element (optionally, a distal coiled element and a proximal coiled element) carried by a distal segment or region of the elongated shaft; and a plurality of perfusion ports in the distal segment of the elongated shaft. The conductive flexible ablation element may have an axial length of 5 mm to 25 mm (e.g., from proximal to distal).

[0097] In this respect, the elongated shaft may have a length such that at least a portion of the distal segment of the elongated shaft can be positioned in the T9, T10, or T11 intercostal vein. In this respect, the conductive flexible ablation element may include a distal conductive flexible ablation element and a proximal conductive flexible ablation element (optionally, a coiled element) carried by the distal segment of the elongated shaft.

[0098] In this respect, a first subset of the plurality of infusion ports may be arranged between the windings of a conductive flexible ablation element, such as an RF electrode, which may be a first electrode or a second electrode. A subset of the plurality of infusion ports may be located distal to the conductive flexible ablation element. The subset of the plurality of infusion ports may be axially arranged between the distal ablation element and the proximal ablation element.

[0099] In this respect, the elongated shaft may lack or have no infusion port between at least one winding at the distal and / or proximal ends of the conductive flexible ablation, and optionally lack or have no infusion port between at least one winding at the distal and / or proximal ends of the first and second coiled electrodes.

[0100] In this respect, the conductive flexible ablation element may include a distal coiled electrode and a proximal coiled electrode. The distal and proximal ends of each of the distal and proximal electrodes may include coils with varying pitch.

[0101] In this respect, the distal infusion port can be within 2 mm of the distal end of the conductive flexible ablation element, which can be the distal end of the distal ablation element. In some cases, the number of distal infusion ports can be two to four or more. The distal infusion ports described herein can be axially aligned, for example, in the exemplary... Figure 8E As shown.

[0102] In this respect, the distal conductive flexible ablation element and the proximal conductive flexible ablation element may be axially spaced apart by no more than 2 mm, and optionally, no more than 1.5 mm.

[0103] In this respect, the central perfusion port between distal and proximal ablation may include two to four ports, or more, and may be axially aligned, for example, in the exemplary case. Figure 8E As shown in the image.

[0104] In this respect, the plurality of infusion ports may have a range of 1.51e-4 to 1.08e-3 in 2 The combination and total area within the range.

[0105] In this respect, the diameter of all of the plurality of infusion ports may be in the range of 0.002” to 0.009”.

[0106] In this respect, the number of the plurality of infusion ports can be in the range of 17 to 344.

[0107] In this respect, the plurality of infusion ports may have such a size and number that when the infusion fluid is delivered from the plurality of infusion ports, the Weber number is in the range of 0.4-53, the infusion fluid is optionally delivered at a rate of 15 ml / min to 50 ml / min, and saline may optionally be used.

[0108] In this respect, the distal segment may have a distal length of 60 mm to 70 mm and may be sufficiently flexible to be advanced from the azygos vein into the intercostal vein. In this respect, the elongated shaft may also have a central transition segment proximal to the distal segment, which optionally has a central length of 15 mm to 25 mm and optionally has a central stiffness greater than the distal stiffness of the distal segment. In this respect, the elongated shaft may have a proximal segment proximal to the central segment, which optionally has a length greater than both the distal and central lengths, and optionally has a proximal stiffness greater than both the central and distal stiffness. In this respect, the central segment may be directly axially adjacent to the distal segment and proximal to the distal segment. In this respect, the proximal segment may be directly axially adjacent to the central segment and proximal to the central segment. In this respect, the distal segment may have a stiffness of 50 D to 60 D, optionally 55 D. In this respect, the central segment can have a hardness of 60 D to 70 D, optionally 60 D to 65 D. In this respect, the distal end of the proximal segment can be no more than 50 mm from the distal end of the catheter. In this respect, the distal end of the proximal segment can be 75 mm to 100 mm from the distal end of the catheter and can optionally extend to the proximal end of the elongated shaft. In this respect, the proximal segment may include a braided reinforcement structure, and the distal segment and the central segment may optionally lack a braided reinforcement structure. In this respect, the hardness of the proximal segment can be 70 D to 80 D, optionally 70 D to 75 D.

[0109] In this respect, the distal segment of the slender shaft can have a linear or straight configuration (e.g., in the exemplary case). Figure 8E (as shown in the diagram), and when the distal section is outside the sheath, it can have an outer diameter of 1.5 mm to 3 mm.

[0110] Any of the first and second ablation elements in this aspect can have a coiled configuration, for example, exemplary Figure 8E Those shown in the image.

[0111] In this respect, the distal segment may include multiple infusion ports with a helical configuration. There may be multiple sets of ports, each with a separate helical configuration, for example, exemplified by Figure 8E As shown in the diagram, multiple sets of infusion ports can be located between the distal and proximal ends of any given electrode, for example, exemplified by Figure 8E As shown in the image.

[0112] In this respect, the distal section of the shaft may have a distal diameter, the central section may have a central diameter, and the proximal section may have a proximal diameter. The distal diameter is optionally smaller than the central diameter, and the central diameter is optionally smaller than the proximal diameter. In this respect, the distal diameter may be from 1.5 mm to 2.5 mm, optionally 2 mm. The central diameter may be from 2.0 mm to 3.0 mm, optionally 2.5 mm. The proximal diameter may be from 2.5 mm to 3.5 mm, optionally 3 mm.

[0113] One aspect of the invention relates to tracking or calculating how much volume of fluid has been delivered into a patient via a catheter. This aspect may include a computer-executable method adapted to calculate the cumulative volume of fluid delivered into the patient via a catheter, while excluding (or not including) fluid that could be delivered via the catheter but was not delivered into the patient's vascular system from the cumulative volume. The method may include initiating the calculation of the cumulative volume of fluid delivered into the patient via the catheter from outside the catheter, and stopping the calculation of the cumulative volume of fluid in response to an exclusion event indicating that the catheter is no longer in the patient's body, to avoid including volumes of fluid that were not delivered into the patient's vascular system in the cumulative volume.

[0114] In this respect, exclusion events can include operator actions that cause the method to stop.

[0115] In this respect, exclusion events can include automatic actions that cause a method to stop.

[0116] In this respect, methods for calculating the cumulative volume of a liquid may include multiplying the flow rate by the elapsed time. The flow rate can 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 to the patient's vascular system when it is determined that the catheter is not in the patient's vascular system.

[0118] In this regard, exclusion events may optionally include, for example, impedance measurements or calculations outside the range or above a high threshold. Exclusion events may include, for example, impedance measurements or calculations above 700 to 900 ohms in unipolar mode. Exclusion events may include, for example, impedance measurements or calculations above 300 to 600 ohms in bipolar mode. Exclusion events may include, for example, impedance measurements or calculations outside the range of 60 to 80 ohms.

[0119] In this respect, exclusion events may include impedance measurements or calculations to determine whether the catheter is outside the body. Initially, the catheter is outside the body, and when a low threshold is crossed, the algorithm may be adapted to determine that the catheter has entered the body, where the pumped saline is included in the cumulative calculation. When it is determined that the catheter is inside the body and a high threshold is crossed, the algorithm may be adapted to determine that the catheter has passed from inside the body to outside the body, where the pumped saline is excluded. Exclusion events may include determining that the catheter is outside the body. If the catheter is outside the body, exclusion events may include impedance measurements above the low threshold. If the catheter is inside the body, exclusion events may include impedance measurements above the high threshold.

[0120] In this respect, the method for calculating the cumulative volume of the liquid can continue uninterrupted until a discharge event occurs.

[0121] In this respect, the liquid can be salt water.

[0122] Any method in this regard can be stored on an external energy delivery console of an ablation system, which can be any external system described herein, adapted to be operatively connected to any ablation catheter described herein.

[0123] One aspect of the invention relates to a method of delivering ablation energy to tissue (e.g., tissue surrounding intercostal veins). The method may include delivering waveforms from any external system herein to any suitable ablation catheter herein, and may include the external system receiving information from any suitable ablation catheter herein.

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

[0125] The methods described herein can be used with any suitable conduit. For example, a first waveform can be delivered to a first electrode (optionally, coiled around the electrode), and a second waveform can be delivered to a second electrode (optionally, coiled around the electrode).

[0126] In this respect, if at least one of the sensed temperature or measured impedance is at or above a threshold limit, and the minimum treatment time has not yet elapsed, the reduction step may include reducing the power of at least one of the first and second waveforms to a secondary power less than the initial power. In this respect, the secondary power may be 5-10 W less than any initial power.

[0127] In this respect, if at least one of the sensed temperature or the measured impedance is at or above a threshold limit, and the minimum treatment time has elapsed, the reduction step may include reducing the power of at least one of the first and second waveforms to a secondary power of 0 W to 1 W.

[0128] In this respect, the first and second waveforms can be multiplexed.

[0129] In this respect, the first and second waveforms can be asynchronous.

[0130] In this respect, delivery from the power module to the first electrode may include delivering a first waveform of ablation RF energy with an initial power of 25 W from the power module to the first electrode. Delivery from the power module to the second electrode may include delivering a second waveform of ablation RF energy with an initial power of 25 W from the power module to the second electrode.

[0131] In this respect, the first waveform and the second waveform can be alternating waveforms that alternate between ablation power amplitude and non-ablation power amplitude. In this respect, the non-ablation power amplitude can be in the range of 0 W to 1 W.

[0132] In this respect, the determining step may include determining whether the sensed temperature is at or above 40°C to 95°C, optionally at or above 90°C.

[0133] In this respect, the receiving step may include receiving information from a temperature sensor associated with a first electrode, such as any coiled electrode described herein. In this respect, the receiving step may include receiving information from a second temperature sensor associated with a second electrode, such as any coiled electrode described herein.

[0134] In this respect, the determining step may include determining whether the measured impedance is at or above 200 to 500 ohms, optionally at or above 500 ohms.

[0135] In this respect, 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 W to 30 W, optionally 20 W.

[0136] In this respect, 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 1 W to 30 W, or optionally by 5 W to 10 W.

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

[0138] In this respect, if the temperature sensed corresponding to the first electrode is at or above the limit, the power of the first waveform can be reduced, and if the temperature sensed corresponding to the second electrode is at or above the limit, the power of the second waveform can be reduced.

[0139] In this respect, the delivery process can take at least 60 seconds.

[0140] In this regard, the delivery process can be performed with the default settings of 30 to 180 seconds.

[0141] Any method in this aspect may also include delivering perfusion fluid to an ablation catheter at a flow rate in the range of 10 to 30 ml / min. Delivering perfusion fluid to an ablation catheter may include delivering fluid to, through, and out of any ablation catheter described herein, including any and all descriptions of perfusion ports from which perfusion fluid may be delivered into the subject's body.

[0142] One aspect of the invention relates to an external device (which may include one or more separate components) suitable for use with any ablation catheter described herein. As used herein, an external device generally refers to one or more components of a system held outside the body of a subject, such as a power module, energy generator, etc. The external device described herein may be adapted to be coupled to or to any ablation catheter described herein to create operative communication therebetween. The external device described herein may be referred to as an external system, and it should be understood that this refers to the external nature of the one or more components. The ablation catheter and one or more external components may be collectively referred to herein as a system. Any feature of this aspect may be combined with, and vice versa, the preceding aspects described herein relating to the delivery of ablation energy. For example, any methods described in the preceding aspects may be stored in one or more memories on any external device of this aspect of the invention and may be used with any ablation catheter of this aspect.

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

[0144] In this respect, the module may include at least one of a temperature limiting module or an impedance limiting module.

[0145] One aspect of the invention relates to the delivery of perfusion fluid to an ablation catheter. This aspect may include a method of delivering ablation energy and perfusion fluid to the catheter to ablate a greater splanchnic nerve, wherein the method includes: positioning the ablation catheter in an intercostal vein; delivering ablation energy to one or more ablation elements carried by a distal region of the ablation catheter; ablating the greater splanchnic nerve lateral to the intercostal vein; and delivering perfusion fluid from multiple perfusion ports in the distal region or segment of the ablation catheter at a rate of 15 ml / min to 50 ml / min.

[0146] Any feature of this aspect of the invention may be included in or combined with any one or more steps of any other aspect, including aspects involving the delivery of ablation energy using any ablation catheter described herein.

[0147] In this respect, delivery of perfusion fluid may include delivering perfusion fluid from multiple perfusion ports in the distal region of the ablation catheter at a rate of 30 ml / min.

[0148] In this respect, delivery of perfusion fluid may include delivery of perfusion fluid from 17 to 344 perfusion ports in the distal region or segment of the catheter.

[0149] In this respect, delivery of perfusion fluid includes delivering perfusion fluid from a plurality of distal perfusion ports arranged distal to one or more ablation elements.

[0150] In this respect, delivery of perfusion fluid may include delivery of perfusion fluid from multiple central perfusion ports arranged between proximal and distal ablation elements.

[0151] In this respect, delivery of perfusion fluid may include avoiding delivery of perfusion fluid from any portion of the distal region or segment of the shaft proximal to one or more ablation elements, optionally since there are no perfusion ports proximal to one or more ablation elements.

[0152] In this respect, the delivery of ablation energy may include delivering energy at a power of 15 W to 50 W, or optionally, at a power of 35 W.

[0153] In this respect, delivery of perfusion fluid may include delivering perfusion fluid to the distal side of one or more ablation elements, rather than delivering perfusion fluid to the proximal side of one or more ablation elements.

[0154] In this respect, delivery of perfusion fluid may include delivery of perfusion fluid from multiple perfusion ports, wherein the multiple perfusion ports optionally have a range of 1.51e-4 to 1.08e-3 in 2 The combined area within the range.

[0155] In this respect, the diameter of the multiple infusion ports can be in the range of 0.002” to 0.009”.

[0156] In this respect, delivering perfusion fluid to multiple perfusion ports at a rate of 15 ml / min–50 ml / min can produce Weber numbers in the range of 0.4–53.

[0157] In this respect, delivering ablation energy may include delivering ablation energy to a first coiled ablation element and a second coiled ablation element that are axially spaced apart on the shaft.

[0158] In this respect, delivery of the perfusion fluid may include delivering the perfusion fluid from at least some of a plurality of ports arranged between the windings of the first and second coiled ablation elements. Attached Figure Description

[0159] The accompanying drawings included herein are for illustrating various examples of the articles, methods, and apparatus of this specification and are not intended to limit the scope of the teachings in any way. In the drawings: Figure 1 This is an isometric view of an ablation catheter positioned in the intercostal vein for ablation of thoracic splanchnic nerves.

[0160] Figure 2 This is a schematic diagram of the transverse view of the ablation catheter positioned in the intercostal vein and the central azygos vein.

[0161] Figure 3 This is a schematic transverse view showing the anatomical structure of the right-biased azygos vein.

[0162] Figure 4This is a schematic transverse view showing the anatomical structure of the left-biased azygos vein.

[0163] Figure 5 This is a schematic transverse view of the anatomical structures showing the location and extent of the azygos vein and the right GSN.

[0164] Figure 6 These are AP fluorescence fluoroscopic images of the patient's chest region from T8 to T12.

[0165] Figure 7 This is a RAO30 fluorescence fluoroscopic image of the patient's chest region from T8 to T12.

[0166] Figure 8A This is a schematic diagram of an ablation catheter with two coiled RF electrodes.

[0167] Figure 8B This is a schematic diagram of an ablation catheter with two coiled RF electrodes and a distal deployable element.

[0168] Figure 8C This is a schematic diagram of the first, second, and third segments of the catheter axis.

[0169] Figure 8D It is a schematic diagram of the distal portion or section of an ablation catheter having injection holes arranged in a spiral pattern between the windings of a spiral electrode and injection holes distal to the distal electrode.

[0170] Figure 8E It is a schematic diagram of the distal portion of an ablation catheter having infusion holes arranged in a spiral pattern between at least some windings of a spiral electrode and multiple infusion holes between the distal electrode and the proximal electrode.

[0171] Figure 9 This is a schematic diagram of an ablation catheter with two coiled RF electrodes, a distal deployable element, and a proximal deployable element.

[0172] Figure 10 This is a schematic diagram of an ablation catheter with two coiled RF electrodes, a distal deployable element, a proximal deployable element, and a central deployable element.

[0173] Figure 11 This is a schematic diagram of an ablation catheter having an RF electrode including an expandable filamentous strut.

[0174] Figure 12 This is a schematic diagram of an ablation catheter with an RF electrode, which includes an expandable balloon with the RF electrode on the surface of the expandable balloon.

[0175] Figure 13A and Figure 13BThis is a schematic diagram of an ablation catheter with an RF electrode, which includes an expandable balloon and an RF electrode made of conductive ink on the surface of the expandable balloon.

[0176] Figure 14 This is a schematic diagram of an ablation catheter with an RF electrode, which includes an expandable balloon with the RF electrode arranged in a Z-shape on the surface of the expandable balloon.

[0177] Figure 15 This is a schematic diagram of an ablation catheter with an RF electrode in a cavity defined by a membrane.

[0178] Figure 16 This is a schematic diagram of an ablation catheter with multiple RF electrode segments on a conical shaft.

[0179] Figure 17A and Figure 17B This is a schematic diagram of an ablation catheter with RF electrode plates on an expandable balloon.

[0180] Figure 18 This is a schematic diagram of an ablation catheter equipped with an ultrasonic transducer.

[0181] Figure 19 The graph includes the RF power delivered to the first and second electrodes, the temperature monitored by sensors associated with the first and second electrodes, and the bioelectrical impedance monitored from the first and second electrodes on the same time axis.

[0182] Figure 20 This is an exemplary machine state diagram of an exemplary saltwater tracking algorithm.

[0183] Figure 21A This is a schematic diagram of an ablation catheter with a flat spiral electrode.

[0184] Figure 21B This is a schematic diagram of an ablation catheter with a flat spiral electrode. Detailed Implementation

[0185] The disclosure herein generally relates to methods for treating at least one of heart failure and hypertension by increasing visceral volume. Some approaches include systems, devices, and methods for transvascular (e.g., transvenous) ablation of target tissue to increase visceral venous volume or venous compliance. In some examples, the devices and methods can be used to ablate visceral nerves to increase visceral volume. For example, the devices disclosed herein can be advanced intravascularly to a target vessel or multiple vessels in the region of the thoracic visceral nerves (“TSNs”), such as the preganglionic greater visceral nerve (“GSN”), lesser visceral nerve, or least visceral nerve, or one of their roots (TSN nerve roots). The target vessel can be, for example, an intercostal vein or azygos vein (or both) or a vein of the azygos vein system, preferably one or more of the lowest (i.e., near the tail) three intercostal veins (which may be T9, T10, or T11).

[0186] Figure 1 The patient's thoracic vertebrae are shown, 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. For simplicity, the lesser visceral nerves and their roots are omitted. The primary objective of the proposed procedure is the ablation of the GSN or its roots, as will be discussed in detail herein. It should be noted that ablation of the lesser visceral nerves or their roots can also be therapeutic and may be the objective of the procedure. A delivery sheath 80 is shown positioned in the azygos vein, and an ablation catheter 81 is shown delivered through the sheath and accessed from the azygos vein into the T11 intercostal vein. The sympathetic trunk extends substantially parallel to the spine, passing consistently close to each costovertebral joint 61 (see [link to relevant documentation]). Figure 2 On the right side of the body, the GSN root branches from the sympathetic trunk, typically extending from the skull to the T9 vertebra, and converges to form the GSN. The GSN runs at an angle from the sympathetic trunk towards the anterior center of the spine and is located anterior to the intercostal veins between the intercostal veins and the parietal pleura (see [link to relevant documentation]). Figure 2 The azygos vein 50 runs along the anterior side of the spine and can, to some extent, be straight and parallel to the axis of the spine, such as... Figure 1 As shown. However, the precise location of the azygos vein relative to the spine varies from patient to patient and at different vertebral levels. At the T9, T10, and T11 vertebral levels, the azygos vein 50 can be as follows: Figure 2 As shown, 69 is centered relative to the midline of the vertebra, which can be seen as... Figure 3 The image shows the azygos vein 50R, offset to the right of the vertebral midline 69, or as shown... Figure 4The image shows the azygos vein 50L, which is offset to the left of the midline of the vertebra 69. The authors' cadaveric studies indicate that, in most individuals, the azygos vein is located within 10 mm to the left or right of the center of the spine at the T9, T10, and T11 levels. Figure 5 The diagram shows the left-biased azygos vein 50L, the right-biased azygos vein 50R, and the centrally located azygos vein 50C, as well as the extent of the azygos vein relative to the center 69 of the spine. Furthermore, the precise position of the right GSN from patient to patient is variable to some extent, including its origin from the sympathetic trunk, the angle of its course, and its destination relative to the spine. Therefore, the position of the GSN relative to the vertebrae can vary at T9, T10, and T11. The authors' cadaveric studies indicate that the position of the right GSN relative to the vertebral center at the T9, T10, and T11 levels ranges from 0 mm to 25 mm to the right of center 69. Figure 5 The range box in Figure 68 is shown.

[0187] Endovascular approaches to transvascular ablation of TSNs, particularly GSNs, may involve one or more of the following steps: accessing the venous vascular system at the patient's jugular or femoral vein using an access guide sheath (e.g., 12F); delivering a delivery sheath (e.g., 9F sheath) to the azygos vein (e.g., at the level of one or two thoracic vertebrae above the target intercostal vein); optionally, delivering a contrast agent through the sheath to visualize the vein's location on fluoroscopic imaging; optionally, delivering a guidewire (e.g., 0.014” guidewire) through the delivery sheath and accessing the targeted T9, T10, or T11 intercostal vein; and delivering an ablation catheter through the delivery sheath (optionally, along the guidewire) to the azygos vein, positioning the ablation element within the intercostal vein, azygos vein, or both; and aligning (or positioning relative to) radiopaque markers on the ablation catheter with 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 damage to one or more non-target structures.

[0188] Important anatomical structures near this area that should not be damaged include the sympathetic trunk 54, the vagus nerve, the thoracic duct, and the esophagus. Therefore, for safety, the ablation zone should be contained within a safe area that does not damage these structures. Due to the variability in the position of the azygos vein and GSN relative to the T9, T10, and T11 vertebrae, the relative position of the GSN relative to the intercostal vein or azygos vein in which the ablation element is located is also variable.

[0189] Bones, blood vessels (if radiopaque contrast agents have been injected), and medical devices (if made of radiopaque materials) are visible under fluorescence fluoroscopy, but nerves are not. Ablation devices and procedural steps designed for ablation of TSNs (e.g., GSNs) via the intercostal vein, azygos vein, or both via a vascular (e.g., transvenous) route can be provided to ensure both effective ablation of the TSN (e.g., GSN) and safety. The procedural steps may include fluorescence fluoroscopy imaging to position the ablation elements(s) of the ablation catheter relative to bone or vascular structures.

[0190] In a first embodiment of the 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 elements and the distal radiopaque marker is advanced from the azygos vein 50 into an intercostal vein 55 at one of the lower three thoracic vertebral levels (e.g., T9, T10, T11). A C-arm is positioned in anterior-posterior (AP) orientation. The proximal radiopaque marker 136 is aligned with the midline 69 of the vertebra, which is possible if the azygos vein 50 is centered or left-biased. If the azygos vein 50 is left-biased, the proximal radiopaque marker will need to be advanced into the intercostal vein to align it with the midline 69 of the vertebra. If the azygos vein is right-biased, the proximal radiopaque marker 136 cannot be placed at the midline 69 of the vertebra. In this case, the proximal radiopaque marker 136 can be placed at the sinus ostium of the intercostal vein, which will be to the right of midline 69. Optionally, the position of the distal radiopaque marker 130 relative to the costovertebral joint (e.g., with the C-arm in RAO orientation) can be assessed to ensure that the sympathetic trunk is not at risk of injury, for example, in patients with very small azygos veins and extreme rightward deviation. The C-arm can be tilted to the right at an angle (RAO orientation) to maximize the 2D projection of the segment of the intercostal vein between costovertebral joint 61 and the anterior midline 69 of the vertebra ( Figure 7For example, the C-arm can be positioned at a right anterior oblique (RAO) angle ranging from 20º to 70º with respect to the ablation element (e.g., within the range of 30º to 60º, within the range of 35º to 55º, approximately 30º, at an angle that maximizes the projected distance between the proximal and distal RO markers). This view allows the user to check to ensure that the distal radiopaque marker is not too close to the costovertebral joint 61. For example, if the distal radiopaque marker is located directly distal to the ablation element, a distance of at least 3 mm (e.g., at least 5 mm) can be selected to ensure that the sympathetic trunk is not damaged. In another example, if the distal radiopaque marker is positioned distal to the ablation element and there is a known interval between them, the distal radiopaque marker can be aligned with or proximal to the costovertebral joint to ensure the safety of the sympathetic junction. If the distal radiopaque marker is too close to or beyond the costovertebral joint, the catheter can be pulled back until an acceptable distance is seen between the distal radiopaque marker and the costovertebral joint. This allows for placement of the proximal radiopaque marker within the azygos vein, especially if the azygos vein is right-biased. If the ablation element comprises multiple ablation elements (e.g., two), ablation can be performed first from the more proximal ablation element before pulling back the catheter to properly place the distal radiopaque marker relative to the costovertebral joint. Subsequent ablation can then be performed from the more distal ablation element.

[0191] In a second embodiment of the 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 elements and the distal radiopaque marker is advanced from the azygos vein 50 into the intercostal vein 55 at one of the lower three thoracic vertebral levels (e.g., T9, T10, T11). A C-arm is positioned for anterior-posterior (AP) orientation. The proximal radiopaque marker 136 is aligned with the intercostal vein sinus ostium 59. The ostium can be located, for example, by injecting a contrast agent and observing the vascular system under fluoroscopy, or if the guidewire is previously positioned in the target intercostal vein, a bend in the guidewire or ablation catheter can indicate the location of the ostium. If the azygos vein is left-biased, the catheter is advanced distal to the ostium to align the proximal radiopaque marker 136 with the midline 69 of the vertebra. In this placement strategy, if the azygos vein is left-biased or centrally located, the proximal radiopaque marker 136 will be aligned with the midline 69 of the vertebra; if the azygos vein is right-biased, the proximal radiopaque marker 136 will be to the right of the midline of the vertebra. Simultaneously, if the azygos vein is right-biased or centrally located, the proximal radiopaque marker 136 will be aligned with the sinus ostium; if the azygos vein is left-biased, the proximal radiopaque marker 136 will be located at the midline 69 of the vertebra. Optionally, the position of the distal radiopaque marker 130 relative to the costovertebral joint (e.g., with the C-arm in RAO orientation) can be assessed to ensure that the sympathetic trunk is not at risk of injury, for example, in patients with very small azygos veins and extreme right-biasedness. The C-arm can be tilted to the right at an angle (RAO orientation) to maximize the 2D projection of the segment of the intercostal vein between the costovertebral joint 61 and the anterior midline 69 of the vertebra. Figure 7 For example, the C-arm can be positioned at a right anterior oblique (RAO) angle ranging from 20º to 70º with respect to the ablation element (e.g., within the range of 30º to 60º, within the range of 35º to 55º, approximately 30º, at an angle that maximizes the projected distance between the proximal and distal RO markers). This view allows the user to check to ensure that the distal radiopaque marker is not too close to the costovertebral joint 61. For example, if the distal radiopaque marker is located directly distal to the ablation element, a distance of at least 3 mm (e.g., at least 5 mm) can be selected to ensure that the sympathetic trunk is not damaged. In another example, if the distal radiopaque marker is positioned distal to the ablation element and there is a known interval between them, the distal radiopaque marker can be aligned with or proximal to the costovertebral joint to ensure the safety of the sympathetic junction. If the distal radiopaque marker is too close to or beyond the costovertebral joint, the catheter can be pulled back until an acceptable distance is seen between the distal radiopaque marker and the costovertebral joint. This allows the proximal radiopaque marker to be placed in the azygos vein, especially if the azygos vein is right-biased.

[0192] In a third embodiment of the method for ablating the right GSN, an ablation catheter having a distal radiopaque marker 130, an ablation element 131, or multiple ablation elements 132, 133, and a gap 135 between the ablation elements and the distal radiopaque marker is advanced from the azygos vein 50 into the intercostal vein 55 at one of the lower three thoracic vertebral levels (e.g., T9, T10, T11). The C-arm is tilted to the right at an angle to maximize the 2D projection of the segment of the intercostal vein between the costovertebral joint 61 and the anterior midline 69 of the vertebra ( Figure 2 For example, the C-arm can be positioned at a right anterior oblique (RAO) angle ranging from 20º to 70º with respect to the AP (e.g., within the range of 30º to 60º, within the range of 35º to 55º, approximately 30º, at an angle that maximizes the projected distance between the proximal RO marker and the distal RO marker). Figure 6 The image shows a fluorescence perspective image in an anterior-posterior (AP) view. In contrast, in... Figure 7The image shows a fluorescence fluoroscopic image at RAO 30º. The catheter is advanced to align the distal radiopaque marker 130 with the costovertebral joint 61. Because the sympathetic trunk 54 is adjacent to the costovertebral joint 61, the gap between the distal radiopaque marker and the ablation element ensures that the sympathetic trunk is not damaged. The gap can be, for example, a length in the range of 0 to 25 mm (e.g., a range of 3 to 25 mm, 5 to 25 mm, or 5 to 20 mm). Optionally, an inflatable balloon 134 can be positioned within the gap on the catheter shaft, which can help anchor the catheter or contain ablation energy proximally to the balloon. Optionally, the catheter shaft 138 distal to the ablation element can be narrower or more flexible than the rest of the shaft to facilitate delivery through the narrower distal portion of the intercostal vein. Optionally, when the distal radiopaque marker is aligned with the costovertebral joint, the ablation element(s) have a length capable of ablation to the anterior midline 69 of the vertebra. For example, (multiple) ablation elements can have a total length ranging from 5 to 25 mm (e.g., from 10 to 25 mm, or from 15 to 20 mm). The ablation catheter can have a proximal radiopaque marker located exactly proximal to the ablation element. Optionally, the user can image the proximal radiopaque marker before delivering ablation energy to ensure it is located at the anterior midline 69 of the vertebra. If the proximal radiopaque marker is located to the left of midline 69, for example, if the patient is very small, there may be a risk of injury to non-target tissues (such as the thoracic duct or esophagus). To mitigate this risk, a catheter with a smaller-sized ablation element can be used, or if the ablation element is made of multiple ablation elements, only the element between midline 69 and the distal radiopaque marker can be activated for ablation. Conversely, if the proximal radiopaque marker is located to the right of midline 69, for example, if the patient is very large, there may be a risk of missing the GSN. To mitigate this risk, another ablation can be performed at the level of another intercostal space or within the same intergastric vein, wherein the position of the ablation element is retracted until the proximal radiopaque marker is aligned with the midline 69.

[0193] In a fourth embodiment of the method for ablating the right GSN, an ablation catheter having an ablation element 131 (which may include multiple ablation elements), a distal radiopaque marker located at the distal end of the ablation element(s), and a proximal radiopaque marker located at the proximal end of the ablation element(s), is advanced from the azygos vein to the intercostal vein at one of the three lower thoracic vertebral levels (e.g., T9, T10, T11). The C-arm is tilted to the right at an angle to maximize the 2D projection of the segment of the intercostal vein between the costovertebral joint 61 and the anterior midline 69 of the vertebra ( Figure 5For example, the C-arm can be positioned at a right anterior oblique (RAO) angle ranging from 20º to 65º with respect to the AP (e.g., within the range of 30º to 60º, within the range of 35º to 55º, approximately 30º). The catheter is advanced to align the distal radiopaque marker with its position relative to the relative edges of the costovertebral joint and vertebral body in an oblique view. For example, in an oblique view, the distal radiopaque marker can be aligned with the midpoint between the relative edges of the costovertebral joint and vertebral body. The ablation elements (multiple) can have a total length expected to cover the GSN location range 68 for most patients. Similar to the previously described method, the proximal end of the ablation elements (multiple) can be positioned at the anterior midline 69 of the vertebra in the case of a centrally or left-biased azygos vein, or on the left side, and in the case of a right-biased azygos vein. Ablation energy can be delivered from the ablation elements (multiple) to ablate this range without moving the catheter. Alternatively, the catheter can be moved to another intercostal level, and a second ablation can be performed using the same methodological steps.

[0194] When performing any exemplary implementation of the placement strategies disclosed above, if the ablation element 131 has a total length of less than 30 mm (e.g., less than 25 mm, less than 20 mm, approximately 15 mm), the sympathetic trunk is expected to be unharmed in most patients, even if the azygos vein is right-biased. Additionally, when performing the methods described herein, if the ablation element 131 has a total length greater than or equal to 15 mm, GSN is expected to be ablated in most patients. Therefore, the ablation element 131 can have a total length ranging from 15 mm to 30 mm to be effective and safe for most patients using these placement strategies. However, a smaller total length of the ablation element may be suitable for exceptional patients. For example, the ablation element may have a total length ranging from 5 to 25 mm (e.g., from 10 to 20 mm, or from 10 to 15 mm).

[0195] 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, and each ablation electrode may be adapted to facilitate the delivery of ablation energy.

[0196] Once an acceptable placement of the ablation element is achieved using one of the exemplary embodiments of the placement strategy described herein, ablation energy can be delivered from the ablation element or multiple ablation elements without the need for catheter movement. Ablation energy can be delivered from the ablation element to ablate tissue circumferentially surrounding the intercostal veins at depths ranging from 2 mm to 10 mm (e.g., 2 mm to 8 mm, 3 mm to 8 mm, approximately 5 mm). Optionally, particularly in cases where the azygos vein is right-biased, this procedure can be repeated at another thoracic vertebral level (e.g., at a more cranial level, a more caudal level, another of the T9, T10, or T11 intercostal veins on the same side of the patient). Alternatively, or in addition to having distal and proximal radiopaque markers at both ends of the ablation element or multiple ablation elements, the ablation elements themselves can also be radiopaque, and the same methods described herein can be used to locate the distal or proximal ends of the ablation elements relative to anatomical landmarks (e.g., the midline of the spine, costovertebral joints, etc.). Therefore, if the ablation element is radiopaque, the phrase "radiopaque marker" used herein can describe the ablation element. In some alternative embodiments, the radiopaque marker may include a relatively long radiopaque marker positioned below or immediately adjacent to one or more ablation elements, wherein the proximal end of the long radiopaque marker is aligned with or extends at least 3 mm proximally to the ablation element, and the distal end of the long radiopaque marker is aligned with or extends at least 3 mm distally to the ablation element.

[0197] For any exemplary implementation of the placement strategies disclosed above, a situation may arise where a portion of the ablation elements is in the azygos vein and the remainder in the intercostal veins, particularly when the ablation catheter has one or more ablation elements with a total length ranging from 10 to 25 mm. The azygos vein is larger than the intercostal veins and has greater blood flow, which may affect the ability to produce effective ablation around or even within the intercostal veins, and may require different energy delivery parameters than ablation performed entirely within the intercostal veins. To address this issue, the ablation catheter may have multiple ablation elements, at least one of which is entirely located in the intercostal veins, and the remainder may be in the intercostal veins, the azygos vein, or both. Different ablation energy delivery parameters can be used for different scenarios; for example, higher power or energy may be delivered to the ablation element in the azygos vein, or ablation energy may be delivered only to the elements located entirely or partially in the intercostal veins. The location of the multiple ablation elements can be determined using fluorescence fluoroscopy or by monitoring the impedance between each ablation element (e.g., an RF electrode) and discrete electrodes.

[0198] Optionally, two or even three levels can be ablated, especially if the azygos vein is right-biased, but this can further enhance efficacy even if the azygos vein is centrally or left-biased.

[0199] Alternative devices and methods of use may include shorter ablation elements for producing relatively short ablations and multiple repositioning to produce multiple ablations within the GSN location range 68. If the azygos vein is centrally located or left-biased, all ablation can be performed in the intercostal vein 55 and cover range 68. If the azygos vein is right-biased, ablation can be performed in the intercostal vein to cover a portion of range 68, and then ablation can be performed at another intercostal level to increase the likelihood of ablation of the GSN. Alternatively, ablation can be performed from the azygos vein, which may use different energy delivery parameters, such as higher energy or power.

[0200] Ablation catheters suitable for ablation of TSNs (e.g., GSNs) from the intercostal veins and / or azygos vein using one or more implementations, such as those employing placement strategies disclosed herein, may have the following features: allowing the ablation catheter to be transvascularly delivered to a desired location in the T9, T10, or T11 intercostal veins; being positioned relative to anatomical features to effectively ablate the target TSN while safely avoiding important non-target structures in most patients; and delivering ablation energy capable of ablating the target TSN. These ablation catheter and system features allow the user to ablate TSNs relatively easily and effectively without sacrificing efficacy or safety. For example, once the ablation elements(s) of the catheter are positioned (e.g., using methods disclosed herein), ablation energy can be delivered from a computerized ablation console by pressing a button or at least by minimal adjustments, repositioning, dragging, twisting, or minimal user decisions regarding energy delivery. Even considering the variability in the location of GSN 68 and azygos vein 67 (see [link to documentation]). Figure 5 The features of the ablation catheter and system disclosed herein can also allow for the ablation of TSN / GSN with a high success rate in most patients through a single placement and energy delivery procedure, or in some cases through additional placement (e.g., in another T9, T10, or T11 intercostal vein) and energy delivery.

[0201] An ablation catheter for GSN transvascular ablation may have a proximal end, a distal end, an elongated axis therebetween, a distal segment (e.g., including a distal 7 cm), and an ablation element on, at, or carried by the distal segment. The ablation element may be adapted (including being sized and / or configured to) produce ablation with a length ranging from 5 mm to 25 mm, preferably 10 to 25 mm (e.g., 15 mm 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 include electrical or fluid connections or to facilitate catheter manipulation. The elongated axis from the strain relief region to the distal end can have a length of 100 cm to 140 cm (e.g., from 110 cm to 130 cm, or approximately 120 cm), allowing delivery of the distal segment to the T11 intercostal vein via an arterial incision such as the femoral vein approach (or other approach locations, such as the jugular, brachial, radial, hepatic, or subclavian veins) in most human patients; or a length of 50 cm to 140 cm, allowing delivery of the distal segment to the T11 intercostal vein via the jugular vein approach in most patients. For delivery via a 9F delivery sheath, the catheter can have a maximum outer diameter of at least 3 mm (e.g., 2.5 mm, 2 mm, 1.5 mm) in its delivery state. In some embodiments, the catheter may optionally have a deployable structure that expands beyond this size once advanced from the delivery sheath and positioned in the target vessel. Ablation catheters used for delivering ablation elements from an intravascular route to the intercostal veins (including from the azygos vein to the intercostal veins), particularly the T9, T10, or T11 intercostal veins, can have an axis that features: facilitating easy tracking along the guidewire, maneuverability, transmission of translational force from the catheter handle, and the ability to pass through sharp bends from the azygos vein to the intercostal vein without twisting. For example... Figure 8C As shown, the catheter shaft may include a first segment 340, a second segment 341, and a third segment 342. The first segment 340 may be more flexible than the second and third segments and may carry ablation elements, such as the two coiled electrodes 133 and 132 illustrated. This first segment may have flexibility capable of passing through sharp bends from the azygos vein to the intercostal vein (e.g., having a radius of curvature >= 5 mm and an angle of up to 120 degrees). The first segment may have a length in the range of 60 mm to 100 mm (e.g., about 65 mm) and may be made of a single-lumen Pebax® tubing with a stiffness of 50 to 60 D (e.g., 55 D).

[0202] The flexibility of the second section 341 can lie between the flexibility of the first section and the third section, and serves as a transition area and strain relief element to resist torsion. For example, the second section can have a length in the range of 15 mm to 25 mm (e.g., about 20 mm) and can be made of a single-cavity Pebax® tube with a hardness of 60 D-70 D (e.g., 60 D-65 D, e.g., 63 D).

[0203] The third segment 342 may be at least a portion of the proximal region of the elongated shaft and may be adapted for maneuverability, torsion resistance, torque transmission, and flexibility. For example, the third segment of the elongated shaft may extend from the proximal end of the conduit to approximately 85 mm from the distal end (e.g., in the range of 75 mm to 100 mm) and may optionally have a wire braid embedded in the outer layer of the shaft. An exemplary material for the third segment of the elongated shaft may be pressed Pebax® with a hardness from 70 D to 75 D (e.g., 72 D). For example, the first segment 340 may be more flexible than the second segment 341, the second segment 341 may be more flexible than the third segment 342, and flexibility may be increased by using a lower hardness material or a more flexible braided outer layer or by not using a braided outer layer. The maximum outer diameter of the elongated shaft may be in the range of 1.5 to 3 mm, at least in the delivery state. Optionally, as Figure 8C As shown, the first segment 340 of the shaft can be made of a tube with a diameter smaller than that of the second segment 341, and the diameter of the second segment 341 can be smaller than that of the third segment 342 of the shaft. For example, the first segment can be made of a tube with an outer diameter of 2 mm; the second segment can be made of a tube with an outer diameter of 2.5 mm; and the third segment can be made of a tube with an outer diameter of 3 mm. Optionally, the elongated shaft can have a tapered, flexible distal end 345, which can have a length in the range of 5 mm to 30 mm (e.g., about 8 mm) and can be more flexible than the first segment. Optionally, the first, second, or third segment of the shaft can have a lubricating coating on its outer surface to further improve delivery through the vascular system. A guidewire lumen can pass through the elongated shaft, with an outlet port 82 located at the distal end of the shaft. The guidewire lumen can be made of, for example, a 0.014” ID polyimide tube located within the lumen of the shaft.

[0204] The ablation catheter may have ablation elements adapted to deliver ablation energy from the vascular surface to the target nerve up to 5 mm in length, with a total length ranging from 10 mm to 25 mm, e.g., 10 mm to 20 mm, or 15 mm to 20 mm. The ablation elements may be made of multiple ablation elements (e.g., two) positioned within an area with a total axial length ranging from 10 mm to 25 mm (e.g., 10 mm to 20 mm, or 15 mm to 20 mm), even if these ablation elements are axially spaced. The ablation elements may include one or more of the following: RF ablation electrodes, coiled wire electrodes, laser-cut RF electrodes, RF electrodes printed with conductive ink, RF electrodes on an expandable balloon (e.g., made of conductive ink or flexible circuitry), conductive membrane RF electrodes, RF electrodes on an expandable cage or mesh, ultrasonic ablation transducers, electroporation electrodes, cryoablation elements, or virtual RF electrodes.

[0205] Ablation elements can be adapted to deliver ablation energy circumferentially, i.e., radially symmetrical around the ablation element and the vessel in which it is positioned. Although the GSN always passes anterior to the intercostal vein and azygos vein, ablation of tissue around the intercostal vein or azygos vein is safe and acceptable, and circumferential ablation allows for a simpler and faster procedure, and is less prone to user error because targeted energy delivery is unnecessary. Features that allow for circumferential ablation may include, but are not limited to: ablation electrodes that expand to uniformly contact the vessel wall circumferentially around the vessel; ablation electrodes used with conductive fluid; electrically insulating balloons or deployable structures that contain ablation energy in a segment of the target vessel to allow it to be radially guided; and ablation elements (such as cylindrical ultrasound transducers) that circumferentially guide ablation energy.

[0206] In some embodiments, the ablation element is an RF electrode, and saline can be delivered to the blood vessel in fluid communication with the RF electrode. A perfusion lumen communicating with the perfusion port can be located distal to and below the ablation element (in some designs, perfusion saline can pass through the ablation element), or in some embodiments, it can be located within a deployable structure. The perfusion lumen can, for example, be a lumen in an elongated shaft in fluid communication with a tube located proximal to a catheter that can be connected to a fluid source and pump.

[0207] Optionally, at least one deployable occlusion structure (e.g., balloon, bellows, wire mesh, braided wire, coated wire mesh, or coated braided wire) may be positioned distal to the ablation element on the axis. The deployable structure can be used to anchor the catheter in place during energy delivery and may improve safety by providing an electrical insulator or containing saline proximal to the deployable structure to prevent ablation of the sympathetic trunk. Optionally, the deployable occlusion structure may be located precisely proximal to the proximal end of the ablation element(s), which can be used to divert blood flowing in the azygos vein away from the ablation zone. For example, the deployable occlusion structure may be a balloon, such as a urethane balloon having a length of about 2.5 mm (along the axis of the axis) and an expansion diameter of about 2.5 mm to 7 mm (e.g., 3 mm to 6 mm, 4 mm to 5 mm). The balloon may be in fluid communication with an expansion port that connects the balloon to an expansion lumen that can be connected to an expansion source on the proximal end of the catheter. Optionally, the expansion lumen may be in fluid communication with an infusion lumen that can be connected to an infusion source and a pump. Optionally, such a catheter may have a perforated balloon, the orifice allowing infusion fluid to exit the expansion balloon and flow to (multiple) ablation elements.

[0208] The ablation catheter may have a proximal radiopaque marker located on the axis at or proximally to the ablation element(s). Optionally, the ablation catheter may include a distal radiopaque marker, which may be positioned on the axis at or distally to the ablation element. Optionally, a gap may exist between the distal radiopaque marker and the distal end of the ablation element, the length of which is in the range of 0.1 mm to 25 mm, for example, 0.1 mm to 5 mm, for example, 0.1 mm to 3 mm, for example, 0.5 mm, 1 mm, or 1.5 mm. For example, as... Figure 2 As shown, the distal radiopaque marker 130 can be aligned with or positioned relative to anatomical landmarks (such as costovertebral joint 61), and a spacer 135 (e.g., 1 mm to 25 mm) is located between the distal radiopaque marker 130 and the distal end of the ablation element 132, ensuring that the ablation element is safely distanced from the sympathetic trunk 54. Optionally, the deployable structure 134 can be positioned in a spacer that can switch between a contracted state (OD similar to axial OD, e.g., in the range of 1.5 mm to 3 mm) and a deployed state (OD increased to the range of 3 to 7 mm). The deployable structure can be a balloon, bellows, mesh, braided silk fabric, coated mesh, or coated braided silk fabric.

[0209] Figure 2An example of an ablation catheter sized and adapted for GSN ablation is shown. The ablation catheter 81 has an elongated shaft sized and adapted to reach the T11 intercostal vein from an insertion site at the femoral or jugular vein. The distal segment of catheter 81 (shown as positioned within intercostal vein 55) includes a distal radiopaque marker 130 aligned with or positioned relative to the costovertebral joint 61, an ablation element 131 comprising a distal conductive coiled RF electrode 132 and a proximal conductive coiled RF electrode 133 or thereof, and an optional inflatable balloon 134 disposed between the ablation element 131 and the distal radiopaque electrode 130. The distal radiopaque marker 130 is optionally spaced 135 distally from the distal end of the ablation element 132, the distance 135 being, for example, in the range of 0 to 25 mm (e.g., 0.1 mm to 20 mm, 0.1 mm to 15 mm, 0.1 mm to 3 mm, 0.5 mm, 1 mm, or 1.5 mm). The catheter 81 also includes a proximal radiopaque marker 136 located at or near the proximal edge of the ablation element 131. In some embodiments, the proximal radiopaque marker 136 is axially spaced between 0 mm and 25 mm from the proximal end of the ablation element 31 (which may be related to the proximal end of the ablation element 133).

[0210] The exemplary axial distance between the marker and the electrode described herein (e.g., 0 mm to 25 mm, or 0 mm to 15 mm) can be integrated into any other ablation catheter described herein, unless otherwise indicated herein.

[0211] Ablation electrodes 132 and 133 (or any other ablation electrodes herein) can be made of, for example, nitinol wire coiled around the catheter shaft, which allows the electrodes to be flexible so that they can pass through sharp bends from the azygos vein to the intercostal vein and also produce long ablation (e.g., 5 to 25 mm). Nitinol is an example of a hyperelastic material that allows (multiple) ablation elements to bend as they pass through anatomical bends and then elastically return to a linear or straight configuration once the electrodes have passed the bend.

[0212] Therefore, any distal segment in this paper can be described as a distal segment with a static (manufactured) linear or straight configuration. This contrasts with distal segments that are reversible or exhibit a nonlinear static configuration (e.g., distal segments with electrodes returning to a coiled configuration).

[0213] Optionally, the ablation catheter 81 includes at least one infusion port 137 (e.g., Figure 2As shown, the infusion port 137 is in fluid communication with an infusion lumen near the coil electrode for delivering fluids (such as saline). For example, saline delivery can facilitate device delivery or removal, or can be used during energy delivery to improve ablation formation and prevent overheating. Optionally, the catheter 81 may include a guidewire lumen 82 for delivery along the guidewire 79.

[0214] Figure 8A A portion of an exemplary ablation catheter is shown, including at least a portion of its distal segment. Figure 8A The ablation catheter includes ablation elements, comprising a distal ablation element and a proximal ablation element. The ablation elements (and other ablation elements herein) include, or are composed of, a distal conductive coiled RF electrode 132 and a proximal conductive coiled RF electrode 133, such as... Figure 8A As shown. Both the distal and proximal coiled electrodes can be helical coils, which surround and are at least partially positioned on the outer surface of the shaft, optionally located in a groove of the shaft. The coiled electrodes can be helical and can have varying directions, pitches, or wire thicknesses, and can be made of circular or strip filaments of conductive materials (such as stainless steel or superelastic nitinol), optionally electropolished, and optionally include radiopaque materials (such as platinum-iridium alloys). Alternatively, one or more coiled electrodes can be made from laser-cut tubes, for example, forming nitinol tubes of a coiled or other flexible type. Alternatively, the ablation element (e.g., ablation element 131) can be made of distal and proximal flexible electrodes in the form of a mesh or braid. Alternatively, the flexible ablation element can include multiple annular electrodes, each annular electrode having a length not exceeding 5 mm, for example, 3 mm. Optionally, the flexible ablation element may have an expandable diameter (e.g., an outer diameter of up to about 5 mm) that can transition from a contracted delivery state to an expanded deployment state, so that it can expand to contact the vessel wall.

[0215] The electrodes described herein, such as the proximal and distal electrodes (e.g., distal electrode 132 and proximal electrode 133), may have lengths ranging from 4 mm to 12 mm, for example, from 5 mm to 11 mm, and in some embodiments, they are or 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 may have the same or substantially the same length, including lengths within the range provided herein (e.g., 5 mm to 11 mm). In some embodiments, the electrodes may have different lengths. For example, in some examples, the distal electrode 132 may be longer than the proximal electrode 133, but these electrodes individually may have any length described herein. In some examples, the distal electrode 132 may be shorter than the proximal electrode 133, but these electrodes individually may have any length described herein.

[0216] For catheters with multiple electrodes, each electrode can be connected to an independent conductor that passes through a slender axis to the proximal region of the catheter, where it can be connected to an extension cable or ablation energy source. This allows each electrode to be energized independently in either unipolar or bipolar mode.

[0217] For some catheters having distal and proximal electrodes, the catheter may include a gap between the distal end of the proximal electrode and the proximal end of the distal electrode. In some embodiments, this gap may be in the range of 0 to 5 mm, for example, 0 mm to 4 mm, for example, 0.1 mm to 1.25 mm, for example, 0.25 mm, 0.5 mm, 0.75 mm, 1 mm, or 1.25 mm. Preferably, the proximal and distal electrodes are not electrically connected to each other. Alternatively, as long as the proximal and distal electrodes are not electrically connected to each other, the proximal and distal electrodes may at least partially overlap each other along their length.

[0218] The gap between the proximal and distal electrodes can be such that it is not large enough to prevent the formation of continuous ablation damage. The gaps described herein (e.g., 0 mm to 5 mm, such as 0.1 mm to 1.25 mm, such as 0.25 mm, 0.5 mm, 0.75 mm, 1 mm, or 1.25 mm) can provide exemplary benefits for providing continuous damage formation.

[0219] The ablation catheter described in this article may include one or more temperature sensors. Figure 8AAn exemplary ablation catheter including at least one temperature sensor is illustrated. The illustrated ablation catheter includes, for example, a proximal temperature sensor 139, which can be positioned to contact a proximal electrode 133 and optionally positioned at the proximal end of the proximal electrode 133. The illustrated ablation catheter also includes a distal temperature sensor 140, which can be positioned to contact a distal electrode 132 and optionally positioned at the distal end of the distal electrode. Any ablation catheter described herein may optionally include another temperature sensor, which may be positioned between the proximal and distal electrodes, or between multiple electrodes. For catheters including one or more temperature sensors, the temperature sensors(s) may be thermocouples (e.g., T-type) or thermistors. Optionally, at least one temperature sensor may extend radially or may extend radially from the catheter axis to contact tissue up to 3 mm away from the catheter surface. The temperature sensors(s) may be connectable to a computerized energy delivery console at a proximal region of the catheter, where signals from the sensors can be input and used in energy delivery control algorithms.

[0220] Any ablation catheter described herein may include one or more perfusion ports (which may be referred to herein as orifices or vents) in fluid communication with a perfusion lumen, which may be connected to a fluid source in a proximal region of the catheter for delivering a fluid, such as saline (e.g., physiological saline or hypertonic saline), into the blood vessel. The ports may be formed in one or more layers along an elongated axis to create fluid communication between the port and the perfusion lumen. The fluid may be used to cool or remove heat from the electrodes and / or vessel walls, flush blood from the vessel to reduce the risk of clot formation or improve ablation consistency, conduct electrical energy from the ablation electrodes, control pressure in the vessel, facilitate delivery of a distal segment of the ablation catheter to a target vessel (e.g., an intercostal vein), or facilitate removal of a distal segment of the ablation catheter from the target vessel. Optionally, one or more perfusion ports may be distal to the ablation element(s) or distal to each of a plurality of flexible ablation elements. In some embodiments, any one of the perfusion ports may be radially positioned below the plurality of flexible ablation elements(s). In some embodiments, one or all perfusion ports may be arranged between the windings of the coiled ablation element such that the ports are not radially below the windings of the ablation element. Optionally, the perfusion ports may be located in the axial gap or interval between adjacent ablation electrodes. Optionally, one or more perfusion ports may be in the cavity of a deployable occlusion structure (e.g., a balloon) and may be used to inflate the balloon, wherein the balloon may have a perforation on its proximal side that allows fluid to escape from the balloon into the target area of ​​the blood vessel.

[0221] Figures 8A-10The distal segment of the ablation catheter is shown, comprising multiple infusion ports between windings of the coiled ablation element (although only port 137 is labeled, the others are visible in the figure). Figure 8A , Figure 8B , Figure 9 and Figure 10 In the side view shown, the exemplary port is linearly aligned parallel to the long axis of the distal segment. Additionally... Figure 8A , Figure 8B , Figure 9 and Figure 10 As shown in the side view, there is an infusion port between each adjacent pair of winding materials (even though coiled elements 132 and 133 are each formed as continuous windings along their length). A central port 137 axially located between the ablation elements may or may not be included. In any embodiment, each port in the distal segment may be located between the windings (in the side view). In other words, in any embodiment, no port may be radially located below the winding structure of the ablation element.

[0222] Optionally, such as Figure 8D As shown, the injection holes (which may be referred to herein as orifices or ports) 137 can be positioned between the windings of the coil electrodes and are circumferentially distributed to deposit brine along the length of the ablation electrode and circumferentially around the electrode. Figure 8D In the process, the injection holes 137 follow a helical path, optionally having the same pitch as the coil electrodes and equal spacing between the holes, such as... Figure 8D As shown. Even as shown in the figure, Figure 8D The examples in the example do not include the center port between the electrodes (such as...) Figure 8A and Figure 8B (As in the example), the injection hole can still be considered to have or follow a helical path. That is, the spacing between segments of the helical port can be greater than the spacing between adjacent ports within a segment. However, Figure 8D The example shown may also include a central infusion port between electrodes (as in...) Figure 8A and Figure 8B (as in the example).

[0223] Infusion orifices can be formed (e.g., laser-drilled) in the tube (or tubular member) before or after the electrode coil(s) are positioned or connected to the tube. Optionally, the size and number of infusion orifices are selected together with the infusion flow rate range to maintain back pressure in the infusion lumen, such that infusion saline is ejected from the infusion orifices, which can uniformly, consistently, and predictably fill the vessel (e.g., intercostal vein) with saline. For example, an ablation catheter can be adapted to receive saline flow rates in the range of 30 to 50 mL / min during ablation and can have 34 infusion orifices with a diameter of 0.003”, or alternatively, 17 infusion orifices with a diameter of 0.009”.

[0224] Optionally, the number of orifices associated with the distal electrode can be greater than that associated with the proximal electrode, and vice versa. Optionally, one or more infusion orifices can be located distal to the distal electrode, for example, within 3 mm distal to the distal electrode. This can improve the cooling of the distal electrode, including a temperature sensor that communicates with the distal electrode, especially when the temperature sensor is located at the distal end of the distal electrode. For example, as Figure 8EAs shown in the schematic diagram of the distal portion of the ablation catheter, infusion orifices 137 can be arranged in a helical pattern between at least some windings of the proximal helical electrode 133, and similarly, infusion orifices 137 can be arranged in a helical pattern between at least some windings of the distal helical electrode 132, and a plurality of infusion orifices 461 can be arranged distal to the distal electrode, and a plurality of infusion orifices 460 can be arranged between the proximal and distal electrodes. In this example, the infusion orifices 137 located between the windings of the proximal coiled electrode 133 and the distal coiled electrode 132 follow a helical path around axis 340, the helical path having the same pitch as or at least sufficiently the same pitch as the helical coiled electrode, such that the orifices 137 are held between the windings of the coiled electrode. Furthermore, the orifices 137 can be spaced apart from each other at a regular interval along the helical path, for example, every 96 degrees (or a regular interval in the range of 4 to 110 degrees), which can provide a uniform circumferential distribution of infusion. The pitch of the coiled electrodes can be tighter at one or both ends of each coil. For example, each end of each coil can be wound around shaft 340 and contact the adjacent turns of the coil, forming a closed loop at each end of the coil where the connection is welded together. This helps to hold the coil firmly on the shaft and accommodate the ends, avoiding the risk of loose wire ends getting stuck in tissue or delivery sheaths. The same welded joint can include an RF conductor and optionally thermocouple wire forming a thermocouple joint, as shown in the distal thermocouple joint 140 at the distal end of the distal electrode 132 and the proximal thermocouple joint 139 at the proximal end of the proximal electrode 133. Due to the reduced coil pitch at the ends of the coil, there is less space to place the infusion orifice. Alternatively, the infusion orifice can be located only in the central region of the coiled electrode, rather than at the reduced pitch location at the ends, such as within the first or last three turns. To compensate for reduced potting at the ends of the coiled electrodes when no holes are placed in the last few turns, potting holes 461 may be positioned distal to the distal electrode 132, and potting holes 460 may be positioned between the proximal electrode 133 and the distal electrode 132. For example, the number of distal holes 461 in the range of 1 to 5 (e.g., 3) may be circumferentially and uniformly spaced (e.g., radially symmetrical) within a distance 462 at the distal end of the distal electrode 132 (e.g., in the range of 0.1 to 3 mm, or 0.1 to 1 mm). Similarly, the number of holes 460 between electrodes in the range of 1 to 5 (e.g., 3) may be circumferentially and uniformly spaced (e.g., radially symmetrical) within a spacing 463 between the distal electrode 132 and the proximal electrode (e.g., in the range of 0.5 to 1.0 mm).Because blood flows from distal to proximal in the intercostal veins, the perfusion saline flowing from the distal orifice 461 will adequately soak and cool the distal turns of electrode 132; the proximal turns of the distal electrode will be soaked and cooled by the saline flowing from the holes between the windings and from the distal orifice 461; similarly, the distal turns of the proximal electrode 133 will be cooled and soaked by the holes between the electrodes 460; and the proximal turns of the proximal electrode will be soaked and cooled by the saline flowing from the holes between the windings and from holes 460 and other holes 137 and 462 associated with the distal electrode. Figure 8E In one exemplary embodiment shown, the catheter has three circumferentially spaced distal infusion holes 461, three circumferentially spaced infusion holes 460 between the proximal and distal electrodes, 15 helically spaced infusion holes 137 between the windings in the distal electrode, and 15 helically spaced infusion holes 137 between the windings in the proximal electrode, for a total of 36 infusion holes, each having a diameter of 0.003”.

[0225] Alternatively, in any of the examples herein, the injection hole may be located below the coil electrode windings and between the windings.

[0226] Alternatively, any device described herein may include a section of tube on which electrodes are positioned, which may be a porous tube made of an inherently porous material, such as a mesh or braided tube.

[0227] Alternatively, any coiled electrode described herein may have a flat shape, such as a strip of conductive material spirally wound around a tube. Compared to a circular filament shape, a flat shape may be easier to deliver or remove from tight blood vessels in some cases. Figure 21AAn exemplary distal portion of an ablation catheter with an ablation element 385 is shown, the ablation element 385 having a plurality of coiled electrodes (in this example, a first electrode 386 and a second coiled electrode 387) made of a flat strip spirally wound around a tubular shaft 388. The flat strip may be a conductive material, optionally a superelastic nitinol strip, shaped as a helical coil having, for example, an inner diameter of only 0.069” + / - 0.004” and a pitch of about 0.047”. Superelastic nitinol has the advantage of resistance to torsion and elastic recovery to a predetermined shape during or after deformation when the device is delivered to a target blood vessel. However, alternative materials such as stainless steel or conductive alloys may be used. Optionally, at least a portion of the strip electrode may be made of a radiopaque material, such as a platinum-iridium alloy. Optionally, the surface of the strip electrode may be etched and passivated. The flat strip may have a thickness in the range of, for example, only 0.002” to 0.003” and a width 389 in the range of 0.010” to 0.020”. Each The length 390 of the coil can be approximately 8 mm + / - 0.5 mm. The flat strip electrode can be applied flush with the surface of the tubular shaft. For example, the tubular shaft can be recessed at the junction of the flat strip and the shaft, or the tubular shaft can be remolded or softened during application of the flat strip to allow it to be embedded in the shaft. Alternatively, the flat strip electrode can extend beyond the surface of the shaft, for example, the thickness of the strip can be in the range of 0.002” to 0.003”. Optionally, the edge 391 of the strip electrode, for example, on the outer diameter, can be rounded, chamfered, or tapered, which can further facilitate catheter delivery to or removal from the target vessel, or can reduce high current density during RF energy delivery. The perfusion port 137 can be positioned as follows: Figure 21A Between the windings of the flat strip electrodes shown, or in other configurations disclosed herein. Figure 21B As shown, another alternative form of the flat helical electrode may include an assembly made of a conductive material 396 (e.g., superelastic nitinol, stainless steel, or alloy) on a non-conductive substrate 397 (e.g., a flexible circuit), which facilitates fabrication. The non-conductive substrate 397 may be, for example, polyimide, and the conductive traces 396 may be attached to the substrate using an adhesive. The assembly may have a wire strain relief element 398 in the substrate through which the conductor can pass from the lumen in the conduit shaft to a wire pad 399 electrically connected to the conductive material 396. Optionally, temperature sensors 139, 140 (e.g., thermocouples) may be positioned on the wire pad together with a conductor supplying RF to the electrode. The assembly may have a thickness ranging from 0.002” to 0.003”, and the conductor thickness ranging from 0.0015” to 0.0025”. The width of each trace may range from 0.010” to 0.020”.

[0228] Optionally, the ablation catheter may have a deployable element that can transition from a contracted delivery state (e.g., with an OD in the range of 1.5 mm to 3 mm) to an expanded deployment state (e.g., with an OD in the range of 2.5 mm to 6 mm). This deployable element serves one or more of the following functions: anchoring a distal segment of the catheter to the target region of the vessel, occluding blood flow, containing the delivered fluid (such as saline), maintaining vascular patency, or acting as an electrical insulator. For example, as... Figure 8B As shown, any catheter described herein may also include a distally deployable element 134 coupled to an optimized perfusion flow, which can generate a virtual electrode providing effective ablation without requiring wall contact. The distally deployable element 134 may be as follows: Figure 8B The balloon shown (e.g., a compliant balloon), or alternatively a bellows or coated stent or mesh, may be used. The distal deployable element 134 is located distal to the ablation element and can be as follows: Figure 8B The diagram shows the proximal electrode and the distal electrode.

[0229] Alternatively, any ablation catheter described herein may have a proximal deployable element. Figure 9 An exemplary ablation catheter is shown, including a proximal deployable element 141, which can be contracted in the delivery state to have an OD in the range of 1.5 to 3 mm, and as shown in the figure. Figure 9 The deployed state shown can be deployed to have an OD in the range of 4 to 10 mm. The proximal deployable element 141 can function as one or more of the following: anchoring the distal segment of the catheter in the target region of the vessel, occluding blood flow, containing delivered fluid (such as saline), acting as an electrical insulator, maintaining vascular patency, acting as a depth stop (e.g., having an OD larger than the targeted intercostal vein) to prevent the distal segment from being advanced too far into the intercostal vein, or guiding blood flow in the azygos vein away from the sinus ostium to facilitate ablation near the sinus ostium. The proximal and distal deployable elements coupled with optimized perfusion flow can create virtual electrodes that provide effective ablation without requiring wall contact. The proximal deployable element can be, for example, as shown in the diagram. Figure 9 The balloon shown is (e.g., a compliant balloon), or alternatively, a corrugated tube, coated stent, or mesh. Any catheter described herein may include a proximal deployable element and a distal deployable element.

[0230] Alternatively, any ablation catheter described herein may include a central or central deployable element. Figure 10 An exemplary ablation catheter is shown, including a central deployable element 142, which can be contracted in the delivery state to have an OD in the range of 1.5 to 3 mm, and as shown... Figure 10The intermediate deployable element is shown to be deployed into an expanded state (e.g., with an OD ranging from 2.5 mm to 6 mm). The intermediate deployable element can serve one or more of the following functions: anchoring the distal segment to the target region of the vessel, occluding blood flow, containing delivered fluid (such as saline), maintaining vascular patency, or acting as an electrical insulator. The intermediate deployable element can be used to isolate the vessel between the distal deployable element and the intermediate deployable element, as well as around the distal ablation element, to create a virtual electrode that provides effective ablation without requiring wall contact. Similarly, a segment of the vessel between the intermediate deployable element and the proximal deployable element can be isolated. The intermediate deployable element can be, for example, as shown in the diagram. Figure 10 The balloon shown is (e.g., a compliant balloon), or alternatively, a bellows or coated stent or mesh. In embodiments where the ablation energy is electroporation, the intermediate deployable element can serve as an electrical insulator to guide current out of the vessel through the tissue surrounding it, thereby more effectively ablating the target nerve. In alternative embodiments, the ablation catheter may have an intermediate deployable element and only a distal deployable element (i.e., no proximal deployable element) or only a proximal deployable element (i.e., no distal deployable element).

[0231] The above disclosure describes an exemplary method for positioning an ablation catheter within an intercostal vein to ablate GSN while minimizing or avoiding damage to non-target structures. The aforementioned ablation catheter (including...) Figure 8A , Figure 8B , Figure 9 and Figure 10 The ablation catheter shown includes one or more radiopaque markers (e.g., distal marker 130 and proximal marker 136) that can be used as part of these positioning methods. Although Figure 8A , Figure 8B , Figure 9 and Figure 10 The ablation catheters described herein are examples of ablation catheters that can be used when performing the methods described herein; however, it should be understood that these methods can be performed using a wide variety of ablation catheters. Therefore, it should be understood that the methods described herein are not limited to the specific ablation catheter described herein. It should also be understood that the ablation catheters described herein do not need to be used with the localization methods described herein.

[0232] Alternative embodiments of TSN / GSN ablation catheters may have one or more features described herein, such as spaced-apart proximal and distal radiopaque markers as described, perfusion lumen(s), temperature sensors(s), guidewire lumen, flexible shaft segment, and may also include alternative ablation elements. For example, the ablation element may be an RF electrode with a different configuration or an ablation element that delivers different types of ablation energy (e.g., ultrasound, electroporation, cryoablation, laser, chemical, or other ablation methods). Features of the ablation catheter described with respect to one embodiment or example herein may be incorporated into other suitable embodiments unless otherwise indicated in this disclosure. Features with the same or similar reference numerals are understood to be optionally included and may be the same components.

[0233] For example, Figure 11 The distal segment of the ablation catheter is shown. The ablation catheter includes an ablation element, which may be an RF electrode comprising a plurality of filamentous struts 143 extending along the length of the ablation element and arranged circumferentially around an axis. The filamentous struts are conductive, for example, made of stainless steel, nitinol, etc., and are convertible from a contracted delivery state (e.g., having an OD in the range of 1.5 to 3 mm) to an expanded deployment state (e.g., having an OD in the range of 2.5 mm to 6 mm) to contact the vessel wall, particularly intercostal veins. The filamentous struts can be deployed by applying tension to the filament, causing movement of a collar held or otherwise fixed to one end of the filamentous strut, thereby shortening the distance between the two ends (which causes the filamentous struts to bend outward). The struts can be heat-shaped as follows: Figure 11 The bias configuration is shown. Alternatively, the RF electrode may have multiple (e.g., two) RF electrodes made of filamentary struts, wherein the multiple electrodes are positioned adjacent to each other, similar to Figures 8 to 9. Figure 10 The coiled electrode is shown in the diagram. Optionally, the filamentous support can be made from a laser-cut tube. Optionally, the distal, proximal, or both ends of the expandable filamentous electrode can have a membrane that, upon expansion, acts to block blood vessels and functions in conjunction with… Figures 8A to 10 The deployable structure shown (e.g., a balloon) serves a similar function.

[0234] Figure 12 An exemplary ablation catheter is shown, having multiple ablation elements carried by an expandable balloon. Figure 12A distal segment of an ablation catheter with an RF ablation element is shown, wherein the ablation element includes one or more conductive elements positioned on an expandable balloon 144. The conductive elements may be thin films, conductive ink, or flexible circuitry. Sensors (e.g., temperature sensors) may also be positioned on the balloon. Optionally, the balloon can be inflated by delivering fluid (such as saline or air) into it. Optionally, the conductive elements(s) or the balloon may have perforations allowing fluid to pass through to cool electrodes or conduct energy. The conductive elements(s) may be cylindrical, 148 (…). Figure 12 ), spiral 149 ( Figure 13A ), each having multiple electrodes 150 in a spiral configuration Figure 13B Electrodes 151 having a wavy (e.g., sine wave) or zigzag shape Figure 14 ), or other types suitable for ablation around the circumference of blood vessels. Figures 12 to 14 The examples shown include optional distal and proximal radiopaque markers, which can be used with any of the positioning methods described above.

[0235] Figure 15 An additional exemplary distal section of an ablation catheter, including a conductive element within a membrane, is shown. Figure 15 The catheter includes an RF ablation element, which is a conductive wire 145 (e.g., a coil) on or around the catheter shaft within a lumen defined by a membrane 185. The membrane can be an ionomer, a conductive membrane, or an exudative membrane. Optional distal and proximal markings are shown as the distal and proximal sides of the balloon, respectively.

[0236] Figure 16 An example of a distal segment of an ablation catheter is shown, which can be used with the localization method described herein. Figure 16Another embodiment of the RF ablation element is shown, wherein the ablation element is a plurality of shorter RF electrodes 146 on a tapered shaft 147. The difference in this embodiment is that the total length of the shaft carrying the ablation element can be longer than the previously described 5 mm to 25 mm (preferably 10 mm to 15 mm). Alternatively, the catheter comprises multiple segments (e.g., two or three), each having a length within that range, but selectively chosen to deliver ablation energy depending on its fit within the intercostal vein. The tapered shaft can be used to fit within a range of intercostal veins (e.g., in the range of 2.5 mm to 5 mm). The distal end is narrower than the proximal end, and the electrodes can be energized independently and selectively. If a distal segment of the catheter is delivered to a relatively narrow intercostal vein, for example having an internal diameter of approximately 2.5 mm, the distal, narrow portion can be advanced into the vein and selected for energy delivery, while the larger proximal portion can remain in the azygos vein and not be used for delivering ablation energy. If the intercostal vein is large, for example, with an internal diameter of 5 mm, the distal segment can be advanced further into the intercostal vein until the larger electrode wedges into the vessel wall. A larger proximal electrode can be selected for energy delivery, while the distal electrode remains inactive to avoid damage to the sympathetic trunk. Optionally, the middle segment of the electrode can be sized to fit an intercostal vein with an internal diameter of approximately 3.5 mm. Multiple electrodes can be coiled wires, laser-cut tubes, or solid electrodes. The electrodes can be radiopaque or have associated radiopaque markings, allowing the user to image the location of the electrodes within the intercostal vein and select which segment of the electrode to activate.

[0237] Figure 17AAnother embodiment of a transvascular ablation catheter 241 for ablation of TSN or GSN from within the intercostal nerve is shown. The catheter 241 may extend along a longitudinal axis. An expandable member, for example in the form of a balloon 242 having an unexpanded state and an expanded state, may be coupled to a distal segment 243 of the catheter. The expandable member (e.g., the balloon) may have a circumferential treatment zone 248 (e.g., in the range of 5 to 25 mm in length, and 10 to 15 mm in length) extending along the longitudinal axis and surrounding the vessel 55 in the expanded state. The catheter includes an electrode assembly 252 comprising a plurality of electrode plates 244 which may be mounted or otherwise secured to the balloon 242. Each electrode plate assembly may include a base supporting a first electrode plate and a second electrode plate, wherein each electrode plate has a pair of elongated bipolar electrodes connected to an electrical trace 249. The electrode plates of each electrode plate assembly may be longitudinally and circumferentially offset from each other. The method may also include: dilating a balloon in the intercostal vein to electrically couple an electrode to the wall of the intercostal vein, and driving bipolar energy between the electrodes of each bipolar pair to therapeutically alter the TSN or GSN within 5 mm of the intercostal vein, causing a redistribution of the patient's blood volume to treat conditions such as pulmonary hypertension or heart failure (e.g., HFpEF).

[0238] Each electrode plate may include a temperature sensor disposed between the electrodes. Inflation of the balloon may couple the temperature sensor to the 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 approximately uniformly heat the wall.

[0239] To achieve an ablation depth of 5 mm to target the GSN from the intercostal vein, the electrode plates can be cooled to allow for greater power delivery without dehydrating the vein wall tissue (which hinders ablation depth). For example, the electrodes can be cooled by circulating coolant within the balloon 242. In one embodiment, coolant can be injected into the balloon 242 from a coolant injection port 246 located at one end of the balloon chamber, and the coolant can exit the chamber through an outlet port 247 located at the opposite end of the chamber, allowing it to return via a catheter through the outlet lumen.

[0240] In another embodiment, the coolant can be deposited into the bloodstream instead of returning through the lumen in the catheter. This embodiment can allow for a thinner, more flexible catheter shaft or a larger coolant delivery lumen to increase the coolant flow rate. The coolant outlet port can be smaller than the coolant injection port to allow pressure to build up in the balloon for inflation. The coolant outlet port can communicate with the lumen, which does not extend through the entire catheter shaft to the proximal end but rather through the distal end of the catheter to deposit coolant (e.g., saline) into the intercostal vein. Alternatively, the coolant outlet lumen can be the same lumen as the guidewire delivery lumen.

[0241] The electrode plates can be positioned around the balloon to form a circumferential ablation pattern that is the same length as the target ablation zone 58 (e.g., up to 20 mm, approximately 15 mm, between 12 and 18 mm). For example, as Figure 17B As shown, a balloon with electrode plates mounted on an elongated shaft 253 can have an undeployed state with a diameter of approximately 1 mm to 2.5 mm and a circumference of approximately 3.14 mm to 7.85 mm, and can expand to a deployed state with a diameter in the range of approximately 3 mm to 5 mm and a circumference in the range of approximately 9.4 mm to 15.7 mm. The electrode plates 244 can be separated or spaced apart at a distance 250 of less than 5 mm (e.g., less than 2.5 mm) and a width or arc length 251 in the range of 3 mm to 3.5 mm. Each electrode plate 244 can have a length of approximately 3 to 5 mm. Figure 17A As shown, the electrode assembly 252 may include a plurality of electrode plates 244 arranged in four separate rows connected by electrical traces 249, these rows being evenly spaced around the circumference of the balloon 242 (e.g., four rows in each 90-degree quadrant). Longitudinally, the electrode plates 244 in one row may be offset from the electrode plates in adjacent rows. When the balloon is in its uninflated state, the spacing between the electrode plates decreases (e.g., to approximately 0 to 1 mm), and adjacent rows interlock with each other. In its inflated state, the spacing 250 between the electrode plates expands to approximately 2 to 5 mm due to the inflatable balloon 242. The balloon 242 may be a compliant material (such as latex) or a non-compliant material that flexibly folds and contracts.

[0242] Alternatively, the electrode plates can be positioned only on one side (e.g., 50%, 40%, 30%, 25% of the balloon circumference) to create a directional ablation pattern that is entirely oriented towards the same side and has a target ablation zone length of 58. For the directional ablation catheter, radiopaque markers can be positioned on a distal segment of the catheter to indicate the radial direction. For example, the radiopaque markers can be asymmetrical and positioned on the same side or opposite side of the directional electrode plates for indication, and the practitioner can twist the catheter away from the vertebrae (which always faces the GSN) to aim at the radiopaque markers and thus at the electrode plates. Figure 17A Several small electrode plates are shown. Alternatively, the device may have larger and fewer electrode plates, for example, two or three directional electrode plates (e.g., 3 to 5 mm long) on ​​the same side of the balloon spanning the target ablation zone 58. The gap between the electrode plates (e.g., 1 to 3 mm) may facilitate bending of the device to cross from the azygos vein to the intercostal vein. Figure 17A and Figure 17BThe ablation catheter may include proximal radiopaque markers and / or distal radiopaque markers, and may be used in conjunction with the positioning methods described herein.

[0243] Proximal to the balloon, the catheter shaft may include a flexible neck 245, which allows the ablation balloon to be positioned in the natural orientation of the intercostal vein. Given the small radius of curvature at this location, a rigid shaft could apply force to the ablation balloon, causing it to twist the intercostal vein and reducing the predictability of the ablation zone. The flexible neck may be made of a softer polymer (e.g., Pebax®) and may have a coil embedded in the material, which provides maneuverability while allowing for flexible bending. This type of flexible neck can be incorporated into other ablation catheters described herein.

[0244] The proximal electrode(s) can be positioned precisely in the intercostal vein near the sinus ostium. Blood flow through the azygos vein can metabolically cool the surrounding tissue, thus hindering ablation formation. A greater amount of ablation power (e.g., RF) or a longer duration can be delivered to these proximal electrodes compared to the other electrodes in the group to compensate for the blood flow cooling.

[0245] The catheter 241 may have a distal radiopaque marker 255 positioned distal to the ablation element (e.g., distal to balloon 242) and / or a proximal radiopaque marker 254 positioned proximal to the ablation element 244 (e.g., proximal to balloon 242). The distal radiopaque marker 255 and the proximal radiopaque marker 254 may be separated by a distance ranging from 5 mm to 25 mm (e.g., 10 mm to 15 mm) along the longitudinal axis of the axial direction. Any other features or descriptions of the radiopaque markers herein may be applied to markers 255 and / or 254.

[0246] Figure 18An exemplary ultrasound ablation catheter is shown. The catheter 220 includes an elongated shaft 225 having a proximal region and a distal segment, and an ablation assembly 232 mounted to or located at the distal segment. The ultrasound ablation catheter 220 has an inflatable balloon 221, which may have a geometry suitable for expansion in the intercostal vein (e.g., an outer diameter 222 in the range of 2.5 to 5 mm in its inflated state) and a length 223 in the range of 8 to 30 mm. Within the balloon 221, a plurality of ultrasound transducers 224 are positioned on the shaft 233 centered on the balloon 221. The transducers 224 may be sequentially placed across a length 226 in the range of 5 to 25 mm to produce an ablation length similar to that capable of producing a target ablation zone 58. Due to the small diameter of the intercostal vein, a reduced balloon size may pose a risk of contact with the transducers or overheating by the transducers, which could cause the balloon to rupture or reduce the effectiveness of the ablation. To mitigate this risk, a strut or protrusion 227 may be positioned between the transducer and the balloon. The strut 227 may, for example, be a polymer thread strand that is elastically pre-shaped to expand radially away from the transducer 224. For longer ablation across the targeted ablation zone, multiple transducers (e.g., three 4 mm long transducers) may be incorporated and spaced apart by a flexible gap 228 to facilitate traversing the small radius of curvature from the azygos vein to the intercostal vein. For example, the shaft 225 may be a braided reinforced polyimide tubing having an optional guidewire lumen 229 for delivery along the guidewire 79 and carrying an electrical conductor energizing the transducer 224. The ultrasound transducer 224 may be cylindrical for generating circumferential ablation around the target vein. Alternatively, the ultrasound transducer can be flat or semi-cylindrical to produce ablation of a segment as part of the circumference of the vein, and a radially identifiable radiopaque marker 230 can be positioned on the distal segment to allow the user to orient the ablation direction toward the patient's anterior side (where the GSN passes over the vein 55). Optionally, the ultrasound transducer can be configured for both imaging and ablation, and the imaging function can be used to assess nearby structures, such as the lungs, spine, and ribs. Imaging ultrasound can be used to confirm that the transducer is aimed at the lungs, which is the orientation of the target GSN. Optionally, the axis can have a flexible neck 231 within 10 mm proximal to the balloon 221 to allow the distal segment to be well located within the intercostal vein.

[0247] In an alternative embodiment of the ultrasound ablation catheter, the catheter may consist of an active ultrasound transducer and an expandable reflector balloon, which may be on the same catheter or alternatively on different catheters. The reflector balloon may have an expansion diameter in the range of 2.5 to 4 mm and a shape on its proximal surface with a concave curvature such as that which focuses reflected waves onto the target ablation zone. The reflector balloon is positioned distal to the transducer and inserted into the narrower intercostal vein, while the ultrasound transducer remains in the larger azygos vein. The ultrasound transducer may be exposed to blood flow in the azygos vein, or alternatively may be contained within a chamber in an expandable balloon filled with a coolant (e.g., a circulating coolant such as sterile water or saline). Ultrasound energy is directed to the distal reflector balloon and reflected and focused onto the tissue surrounding the splanchnic nerves. An advantage of this approach is that the active ultrasound transducer can be made larger and does not require a sharp bend from the azygos vein to the intercostal veins. A second advantage is that several intercostal veins can be used for target ablation using the same catheter.

[0248] The catheter 220 may have a distal radiopaque marker 230 located distal to the ablation element (e.g., distal to the 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 mm to 25 mm (e.g., 10 mm to 15 mm) along the longitudinal axis of the axis.

[0249] Figures 8A to 10 Exemplary ablation catheters are shown. These example ablation catheters include ablation elements comprising a first flexible coiled ablation electrode and a second flexible coiled ablation electrode spaced apart axially. Having a first and second electrode, rather than a single, longer electrode, may be advantageous to avoid the tendency for a single, longer electrode to primarily heat tissue towards one end of the electrode. Therefore, having more than one electrode can facilitate the production of long and consistent ablation within the tissue. Figures 8A to 10 Examples of ablation catheters that can produce more consistent continuous ablation of desired lengths (e.g., 10 mm to 25 mm, 15 mm to 25 mm, 15 mm to 20 mm).

[0250] Another exemplary advantage of having a first and second electrode compared to a single, longer electrode is that energizing can be applied to only a single, relatively short electrode instead of a single, longer one. This can be advantageous when the patient's anatomy requires or may benefit from shorter ablation, for example, when the azygos vein is precisely centered. In these cases, a longer single electrode can make it difficult or dangerous to safely ablate tissue while avoiding non-target structures. This is described in more detail elsewhere in this article.

[0251] in addition, Figures 8A to 10An ablation catheter is shown having a first ablation element and a second ablation element axially separated by a gap or spacer. The gap is small enough (i.e., not too large) to create continuous damage when the first and second ablation elements are energized, yet large enough to avoid short circuits.

[0252] Therefore, the design features of the distal segment of the ablation catheter in this paper (e.g., Figures 8A to 10 It provides the following exemplary benefits: allowing distal segments to be advanced to the location in the intercostal vein and reliably producing continuous ablation of at least 10 mm to 25 mm in length, while allowing shorter ablation segments as needed based on the patient's anatomy.

[0253] In some applications, the ablation energy is RF, and the energy delivery controller is adapted to deliver RF power in the range of 15 W to 50 W. In some implementations, the controller is adapted to deliver RF power in the range of 15 W to 40 W, in the range of 15 W to 35 W, or in the range of 20 W to 35 W, such as about 25 W, about 30 W, or about 35 W.

[0254] In some applications, energy is delivered over a time period between 25 and 120 seconds. For example, energy can be delivered for 90, 100, 110, or 120 seconds, wherein for a portion of that time period (e.g., half), energy can be delivered to the first electrode, and for the remaining portion of that time period (e.g., half), energy can be delivered to the second electrode.

[0255] In some methods of use, the perfusion flow rate during ablation is from 10 mL / min to 50 mL / min (e.g., 10 mL / min, 15 mL / min, 20 mL / min). Optionally, the flow rate can be automatically changed by a control algorithm in response to changes in measured temperature, impedance, or phase. Using the apparatus and methods disclosed herein, TSNs can be ablated in a relatively safe manner with minimal or reduced adverse effects, such as damage to the lungs or other nerves. Some embodiments of the methods of use described herein can temporarily occlude blood flow and reduce the effects of venous rupture, thus advantageously avoiding the challenges of altering the thermal and electrical environment during the heating process. Some embodiments of the methods of use described herein can ablate nerves up to 5 mm from the target vessel. Some apparatuses described herein are sized and configured for delivery and localization in vascular systems designated for ablation of target nerves (e.g., TSN, GSN).

[0256] Some of the devices described herein may have one or more features that provide safe delivery to the target blood vessel.

[0257] Some of the devices and methods used in this paper can safely deliver energy through temperature-monitored energy delivery.

[0258] Some of the methods used in this paper can generate damage to nerves that are up to 5 mm away from the target vessel and within the target area through a single energy localization and delivery, the damage having a continuous lesion length from 5 mm to 25 mm (e.g., 10 mm to 25 mm, or 15 mm to 20 mm (e.g., 15 mm, 16 mm, 17 mm, 18 mm, 19 mm, 20 mm)).

[0259] Some of the apparatuses and methods described herein are adapted to avoid the risks of boiling, hot spots, or unstable energy delivery that could reduce ablation efficacy. Furthermore, some implementations may include neural stimulation to identify target or non-target nerves to confirm localization before ablation or to confirm technical success during or after ablation.

[0260] Preferably, but not necessarily, the ablation method produces a continuous ablation zone (i.e., without separate, discrete ablation tissue areas that are not connected to each other). This ensures that the tissue area where the target GSN nerve or GSN nerve root is likely located is most likely to be effectively ablated by the ablation energy. The continuous ablation zone can be circumferential or smaller than circumference.

[0261] Optionally, an ablation confirmation test can then be performed, for example, by delivering a neural stimulation signal. The physiological response to the ablation confirmation test (e.g., visceral vasoconstriction, increased heart rate, increased blood pressure) can be monitored. If the physiological response indicates that the first lesion does not provide a clinically significant amount of GSN blockage (e.g., by observing a lack of physiological response), ablation energy can be delivered from the ablation catheter to create a second lesion in tissue up to 5 mm from the second intercostal vein. A distal segment of the ablation catheter can be moved to the third intercostal vein, which is superior to (e.g., superior to and adjacent to) the second intercostal vein. The same or different ablation confirmation tests can be performed, followed by another monitoring test. If the physiological response indicates that the first and second lesions do not provide a clinically significant amount of GSN blockage (e.g., by observing a lack of physiological response), ablation energy can be delivered from the ablation catheter to create a third lesion in tissue up to 5 mm from the third intercostal vein. Any confirmatory ablation test may include delivering a nerve stimulation signal from a stimulating electrode positioned on a distal segment of the ablation catheter, the nerve stimulation signal being configured to generate an action potential in the thoracic splanchnic nerve. Alternatively or additionally, ablation confirmatory tests may include a leg-raising test. Alternatively or additionally, ablation confirmatory tests may include increasing fluid volume into the venous system. Alternatively or additionally, ablation confirmatory tests may include a hand-grip test. Alternatively or additionally, ablation confirmatory tests may include measuring venous compliance or volume.

[0262] In an exemplary method of ablation confirmation testing that includes a leg-raising test, the method may include any of the following steps. Prior to ablation in the lowest intercostal vein, a baseline measurement, including a measurement of total venous compliance including the central venous and visceral bed, can be obtained by raising the leg and measuring changes in central venous pressure and waiting for equilibrium. The leg can then be lowered to allow equilibrium, thereby redistributing blood back to the leg. Ablation in the lowest intercostal vein (e.g., T11) can then be performed as described herein. The leg can then be raised, followed by waiting for equilibrium and re-measuring the central venous pressure. Measurements can then be performed to determine if there is an appropriate decrease in total venous compliance. If yes, the GSN has been successfully ablated. If no, ablation in the next higher intercostal vein (e.g., T10) can be performed as described herein. This measurement can be repeated. An appropriate decrease in total venous compliance can then be determined. If yes, the GSN has been successfully ablated. If no, ablation in the next higher intercostal vein (e.g., T9) can be performed.

[0263] In an exemplary method of ablation confirmation testing that includes hand gripping or other activities of the sympathetic nervous system (SNS) that increase outflow to the visceral bed, the following steps may be included. Ablation may be performed in the lowest intercostal vein (e.g., T11). Venous compliance may then be measured. A predetermined amount of hand gripping may then be performed (e.g., 60 seconds). Venous compliance may then be measured again. If there is no change in venous compliance, the initial ablation is sufficient to achieve a clinically significant result. If a decrease in compliance persists, some SNS activity induced by hand gripping is underway. Therefore, ablation of the lowest intercostal vein is insufficient to achieve a clinically significant effect. Ablation may then be performed in the next higher intercostal vein (e.g., T10). A hand gripping test for a predetermined amount of time (e.g., 60 seconds) may be performed. Venous compliance may then be measured again. If there is no change in compliance, a second ablation is sufficient. If compliance decreases, some SNS activity induced by hand gripping is underway, and therefore ablation in the next higher intercostal vein is insufficient to achieve a clinically significant effect. Ablation can then be performed in the next higher intercostal vein (T9). At this point, the procedure is complete because ablation above the level of the third lowest intercostal vein was not intended.

[0264] Energy delivery algorithm One aspect disclosed herein relates to an energy delivery algorithm, which is particularly well-suited for circumferentially ablating tissue around narrowed vessels (e.g., intercostal veins or other similar vessels) from an ablation catheter to a depth of at least 5 mm and at most 10 mm. The ablation catheter may be... Figure 1 , Figure 2 , Figure 8A , Figure 8B , Figure 8C , Figure 8D, Figure 8E , Figure 9 , Figure 10 , Figure 21A and Figure 21B Any of the catheter embodiments shown, wherein the ablation catheter includes a first electrode and a second electrode (e.g., two coiled electrodes, each electrode having a length in the range of 2.5 to 10 mm, preferably 5 to 8 mm, an outer diameter in the range of about 1.5 to 3 mm, and a distance between the electrodes in the range of 0 to 5 mm).

[0265] A first implementation of the energy delivery algorithm is called "multiplexed monopolar RF," in which RF pulses are delivered to multiple (e.g., two) electrodes in a monopolar configuration with asynchronous waveforms. Each electrode receives a pulse waveform of RF energy that alternately turns on and off at a stable frequency. The waveform can be, for example, a square wave, a sine wave, or other alternating waveforms. The on-time delivers ablation-level RF power, while the off-time delivers non-ablation-level RF power (e.g., approximately 0.1 W in the range of 0 W to 1 W). The waveforms for each electrode are asynchronous, meaning that the waveforms are time-aligned such that the on-time of one electrode is aligned with the off-time of the remaining(s) electrodes(s), and vice versa. The algorithm has an ablation mode activated by a user, for example, by pressing a button or foot pedal. Figure 19 As shown, the ablation pattern algorithm may include parameters that are optionally defined by the user, or that can be set by default until the user changes them, or parameters that can be automatically defined. Note that Figure 19 It was not drawn to scale, and the total time t was shortened in order to simplify the explanation of parameters and concepts. TOTAL For example, if the total time is 180 s and the pulse widths of the first and second electrodes are both 2 s, the actual graph would show 45 cycles; however, for simplicity, fewer cycles are shown. The parameters may include the initial power P. i First electrode pulse width PW1, second electrode pulse width PW2, total treatment time t TOTAL Minimum treatment time, locked time period t LO Secondary power P2, and optional lower power levels. Initial power P i This refers to the initial delivery to each ablation electrode at the start of the energy delivery protocol (e.g., Figure 8A , Figure 8B , Figure 8C , Figure 8D , Figure 8E , Figure 9 and Figure 10The amplitude of the radio frequency power (RF power in watts) of the proximal electrode 133 and distal electrode 132 shown. The initial power can be selected in the range of 15 W to 50 W, preferably in the range of 20 W to 50 W, and can have a default setting of 35 W (e.g., when the flow rate is in the range of 10 to 50 ml / min). The first electrode pulse width PW1 is the duration of each pulse of RF energy delivered to the distal electrode 132 (i.e., the ablation portion of the waveform), and can be selected in the range of 0.5-4 s (e.g., 1-3 s, preferably 2 s), and has a default setting preferably of 2 s. The second electrode pulse width PW2 is the duration of each pulse of RF energy delivered to the proximal electrode 133 (i.e., the ablation portion of the waveform), and can be selected in the range of 0.5-4 s (e.g., 1-3 s), and has a default setting preferably of 2 s. Some embodiments may have more than two electrodes, and therefore may have pulse width parameters associated with each of them. The off-period of the electrode waveform can be equal to the duration of the on-period of the remaining electrodes(s). In an implementation with four electrodes, alternating electrodes (e.g., the first and third electrodes) can be synchronized together and asynchronous with the remaining electrodes (e.g., the second and fourth electrodes). Total treatment time t TOTAL This is the duration from the start to the end of ablation energy delivery, and can be selected within the range of 60s to 400s (e.g., 120 to 200s), preferably 180s. The minimum treatment time is an optional portion of the total treatment time that begins at the start of ablation energy delivery (e.g., less than or equal to the total treatment time); if the temperature or impedance limit is reached before the minimum treatment time is completed, the power can be reduced to a secondary power level or a subsequent lower power level; if the temperature or impedance limit is reached after the minimum treatment time is completed, the power can be reduced to zero (e.g., ablation energy delivery can be terminated). Lockout period t LO This is the time period following an event that triggers a response (e.g., exceeding a temperature or impedance limit, and the algorithm responds by reducing power) to allow tissue temperature to respond to that response (e.g., a decrease in temperature). During the lockout period, the algorithm may ignore temperature or impedance measurements of the electrode or all electrodes associated with the trigger unless they indicate a critical error, such as a critical temperature limit T. CU (e.g., 105°C or higher), critical lower temperature limit T CL (e.g., 20°C or lower), upper limit of critical impedance Z CU(e.g., 800 or greater ohms, 900 or greater ohms, 1000 or greater ohms, user-selectable values ​​between 800 and 2000 ohms) or a critical impedance lower limit (e.g., 50 ohms or less), critical error may indicate device damage. The lockout period can be selected from 2 s to 7 s, or alternatively, a pulse width up to 4 pulse widths, with a default setting of 5 s. Secondary power P2 refers to the magnitude of the RF power in watts less than the initial power, for example, 5 to 10 W less than the initial power. If, for a temperature sensor with a sensed temperature limit (e.g., distal temperature sensor 140 or proximal temperature sensor 139) or an electrode associated with an electrode used to measure the impedance limit (e.g., distal electrode 132 or proximal electrode 133), a temperature T is reached or exceeded... L or impedance limit Z L (For example, in the range of 200 to 500 ohms), then the power level is changed to secondary power. Alternatively, if one of the temperature sensors measures a temperature higher than the temperature limit T, L This allows for power reduction across all electrodes. Optionally, algorithm parameters can include other power levels lower than the secondary power, such as tertiary power levels, quaternary power levels, etc. Alternatively, user-defined parameters can be power reduction P. d It is not secondary power. Power reduction P d This is the amount of power reduction triggered by exceeding the temperature limit or the impedance limit, and is selectable from 1 W to 30 W, with a default of 5 W. Optionally, the power reduction can be variable or calculated as a percentage of the previous power level (e.g., a percentage in the range of 1% to 30%). The power reduction occurs when the power decreases to an absolute level such as the secondary power, or when the power reduction is reduced and a minimum power P is reached. 最小 (For example, in the range of 1 to 10 W, e.g., 5 W) and if the temperature remains above the temperature limit or the impedance remains above the impedance limit, the algorithm may react by: a) terminating the ablation power to the electrode associated with the trigger and continuing to deliver ablation power to the remaining electrodes(s) using an alternating current waveform or continuous RF; b) terminating the ablation power to all electrodes; c) increasing the perfusion fluid flow rate; or d) adjusting the temperature limit. If treatment is terminated because the temperature cannot be maintained below the temperature limit or the impedance cannot be maintained below the impedance limit, or due to any other error, the algorithm may instruct the user to reposition the device, remove the device for inspection, or check the device settings.

[0266] Once activated by the user, saline can be pumped from the perfusion source through the catheter and out of the perfusion port 137. This can be done before the device is placed in the patient to prepare the perfusion lumen or test functionality, or while the device is being advanced into place, or during removal of the device, and this can facilitate delivery or removal. During this time, the flow rate or pump speed can be selected by the user in the range of 0 to 50 mL / min. Optionally, ablation will not begin unless the flow rate is in the range of 15–30 mL / min.

[0267] Saline tracking is characterized by an algorithm that calculates the volume of saline delivered to the patient (using the flow rate to deliver saline to the patient's vascular system) by, for example, multiplying the flow rate by the elapsed time or calculating the area under the curve of the flow rate versus time, and displays this volume on a user interface (e.g., on a computerized console). Furthermore, the algorithm can be implemented through manual input or by using one or more input signals (e.g., by a temperature sensor on the catheter). Figure 8AAn automated detection algorithm (using sensors 139 or 140) senses temperature, or unipolar impedance, or bipolar impedance to determine whether the catheter portion delivering the perfusion fluid is outside or inside the body. When the algorithm determines that the catheter is inside the patient (or in a delivery sheath inserted into the patient), any saline solution pumped by a pump connected to the computerized control panel will be considered when calculating the saline volume delivered to the patient. When the algorithm determines that the catheter is not inside the patient, any saline solution pumped by a pump connected to the computerized control panel will not be considered when calculating the saline volume delivered to the patient. This feature helps the user determine how much saline solution has been introduced into the patient's fluid system, which may be a concern for some patients. Optionally, an alert can be triggered if a predetermined saline volume has been reached or is close to being reached. When the device is outside the body, the saline perfusion flow rate can be turned on, for example, to prepare the perfusion lumen or test the function of the catheter and perfusion system. To determine how much volume has been delivered to the body, the saline tracking algorithm can distinguish between inside and outside the body by manual input. This can be accomplished by having the user press an actuator when the catheter is inserted into the body, which signals the algorithm to begin calculating the volume when the pump is activated. If the catheter is removed from the body, the user can press the actuator to signal the algorithm that the catheter is not in the body, whereby the calculation of the accumulated saline volume is paused. Any volume delivered outside the body is not included in the calculation of the saline volume delivered to the patient. If the catheter or other catheters are returned to the patient for subsequent treatment, any saline delivered to the patient is added to the volume calculation by the user pressing the actuator to restart tracking. Alternatively, the saline tracking algorithm can automatically identify whether the perfused ablation catheter is in the body by monitoring the unipolar impedance measured between one or more ablation electrodes and a grounding plate, or alternatively, by monitoring the bipolar impedance measured between two ablation electrodes. For both in vivo and in vitro detection, unipolar impedance has the advantage over bipolar impedance because unipolar impedance completes the circuit from at least one of the electrodes on the catheter through the body to a discrete grounding plate placed on the patient's skin, while bipolar impedance completes the circuit from the first electrode on the catheter through a conductive medium to the second electrode on the catheter. The conductive medium can be inside the patient's body, such as blood or tissue, but it can also include saline or an external conductive medium, for example, in the case where the electrode is immersed in a saline bath or in the case where saline is infused through a catheter and wets the electrode to close the circuit. However, bipolar impedance can still be used to detect changes in the environment and is useful in saline tracking algorithms. When ablation therapy is not running, very low (non-ablative, e.g., 0.1 W) power can be delivered, allowing impedance to be measured. For example, in monopolar mode, if the catheter is inside the body and connected to a console, and a grounding plate electrically connected to the console is connected to the patient's skin, the monopolar impedance may be within a specific range identifiable from an external catheter.For example, based on experience, a unipolar impedance measurement in the 700-900 ohm range in unipolar mode may indicate that the distal region of the catheter with electrodes and infusion orifices is within the sheath of the patient's vascular system; an impedance measurement with a significant decrease from sheathed impedance (e.g., in the range of 80 to 130 ohms) may indicate that the distal region is within the vascular system and outside the sheath; and a value above the high impedance threshold in unipolar mode (e.g., a high impedance threshold of 900 ohms, above 2000 ohms, above 3000 ohms) may indicate that the electrode is outside the body or that the grounding plate is not properly connected. Alternatively, a bipolar impedance measured in the range of approximately 300 to 600 ohms (e.g., approximately 500 ohms) (e.g., measured by passing current through a conductive medium between two ablation electrodes on the distal region of the catheter) may indicate that the distal region is within the sheath and in vivo; or a bipolar impedance in the range of 60 to 80 ohms may indicate that the distal region is outside the sheath and in the vascular system; high impedance thresholds (e.g., above 600 ohms, above 900 ohms, above 2000 ohms, above 3000 ohms) may indicate that the electrodes are outside the body or that the catheter circuitry has been broken. If the measured impedance is below the high impedance threshold, the algorithm can determine that the distal region of the ablation catheter where the saline is being released is in vivo, taking into account the accumulated saline volume; and if the measured impedance is above the high impedance threshold, the distal region is outside the body, in which case the pumped saline is not considered in the accumulated volume. Optionally, when a change in in vivo / out-of-body status is detected, the algorithm may display a message requesting user confirmation of the change. Optionally, the user can input a known volume of saline that has been injected by other means (e.g., by injecting contrast agent solution from a syringe into a delivery sheath), and this known volume can be added to the cumulative volume calculation.

[0268] Figure 20A machine state diagram illustrating the automatic saline tracking algorithm is shown. Starting at the main treatment screen 321, where the ablation catheter is connected to the console and is external to the body, and a grounding plate is connected to both the patient and the console, the user can press button 325 to enable saline tracking 326. This initiates the automatic calculation of the pumped saline volume, where the calculation determines how much saline volume is deposited in the body, and optionally, how much saline was pumped as the catheter leaves the body. If the ablation catheter is inserted into the body, the bioelectrical impedance should drop 322 to within the range indicating tissue contact, and a message suggesting the user begin saline tracking 323 is displayed. The user can press a button to confirm 324 this message, which tells the algorithm to include the accumulated pumped saline in the total accumulated volume of saline deposited in the body. If the catheter is removed from the body, the impedance 327 is measured to rise to a level outside the range associated with body contact, and a message is automatically displayed suggesting the user pause saline tracking 328. The user can press a button to confirm 329 this message, which tells the algorithm to exclude the accumulated pumped saline from the total accumulated volume of saline deposited in the body. In addition, the user can press button 330 at any time to pause saline tracking, or pause the calculation of saline volume including pumped saline 331 in the saline deposition calculation. Alternatively, instead of automatically defining catheter presence in the body based on impedance, the algorithm can alert the user when it believes the catheter is outside the body, and the user can manually select the flow rate to be excluded from the total saline tracking volume. The user can press the reset actuator to reset the total volume to zero.

[0269] Alternative saline tracking algorithms can ignore rapid increases in impedance within a predetermined range to avoid incorrect retrieval determinations. These rapid increases in impedance could be caused by injection of contrast agent solution or saline near the ablation electrodes(s) while the catheter is in vivo. To distinguish between the injection of contrast agent solution or saline and the distal region from which the catheter is removed or inserted from the patient, the algorithm can have two impedance thresholds when a large change in impedance is detected. These thresholds are used depending on whether the system is in vivo or in vitro mode. If the catheter is not in the patient's body (i.e., in vitro), a first impedance threshold (e.g., approximately 500 ohms in the range of 400 to 600 ohms) can be used to automatically indicate that the catheter has been inserted into the body when the impedance drops below this first threshold. If the catheter is in the patient's body (i.e., in vivo), a second impedance threshold (e.g., approximately 900 ohms in the range of 800 to 3000 ohms) can be used to automatically indicate that the catheter has been removed from the body when the impedance rises above this second impedance threshold. For example, the ablation catheter may be outside the patient's body, and the impedance may be above a second threshold, such as 900 ohms; if the saline pump is running, the algorithm determines that the catheter is not inside the body, and the saline volume is not included in the cumulative calculation; the catheter may be inserted into the patient's body, and the impedance will drop below a first threshold, such as 500 ohms, where the algorithm determines that the catheter is inside the body and considers any pump movement in the cumulative calculation; injection of saline or contrast agent will cause the impedance to rise above the first threshold, but since the catheter is inside the body, the algorithm determines that this rise does not indicate removal, and therefore continues to consider any pump movement in the cumulative calculation; if the catheter is removed from the body, the impedance will rise above a second threshold, such as 900 ohms, and the tracking algorithm will determine that the catheter has been removed, and no pump movement will be considered in the cumulative calculation. Optionally, the first and second thresholds can be adjusted or selected in the user settings. The catheter can be instructed to be used with a saline of a consistent concentration (e.g., 0.9% physiological saline) for the algorithm to function properly.

[0270] In addition to calculating the accumulated injected saline, the algorithm can optionally modify other characteristic behaviors depending on whether the system is in in vivo or in vitro mode, for example as described in Table 1.

[0271] Table 1

[0272] If the bipolar impedance is low (e.g., less than 500 ohms) and the unipolar impedance is high (e.g., greater than 900 ohms), another use of algorithmic bipolar impedance monitoring can be to display messages to users to check if discrete grounding plates are not connected correctly.

[0273] If the bipolar impedance is high (e.g., above 900 ohms), and the infusion pump is running and the system is in in vivo mode, another use of algorithmically performed bipolar impedance monitoring can be to display a message to the user to check for open circuits on one or both electrodes.

[0274] During the ablation mode algorithm, the pump can be activated to infuse saline from the perfusion port 137 at a flow rate in the range of 15 to 30 ml / min, for example, over a period of 5 seconds, before the delivery of ablation energy begins. Then, radio frequency (RF) energy, for example, having a frequency in the range of 350 to 500 kHz, is delivered from the computerized energy console at an initial power for a duration of one pulse width (e.g., the first electrode pulse width) to the first electrode (e.g., the distal electrode 132) of a plurality of electrodes in monopolar mode (i.e., returned via a grounded electrode). The first electrode (e.g., the distal electrode) then enters a shutdown period of its waveform (e.g., with 0 W of power or a low power of less than 1 W), while RF delivery to the second electrode (e.g., the proximal electrode) begins at the initial power for the duration of the second electrode pulse width. Optionally, if the ablation device has more than two electrodes, power can be delivered to subsequent electrodes(s) at appropriate pulse widths before repeating the delivery of power to the first electrode(s). Alternatively, power may be delivered to the electrodes in other orders or combinations without departing from the spirit of this disclosure. Throughout the total treatment time, the RF power is continuously multiplexed through each electrode unless an event triggers titration or stops the delivery of ablation RF.

[0275] Throughout the ablation mode algorithm, and optionally before or after, the temperature can be controlled by a temperature sensor ( Figure 8A , Figure 8B , Figure 9 and Figure 10 (140 and 139) are measured and displayed on the console. During the ablation mode algorithm, these temperatures can be compared with a predefined temperature limit T. L In comparison, the temperature limit T L The temperature can be in the range of 40°C to 95°C, preferably 90°C. Because the space in the blood vessel surrounding the electrode and temperature sensor is perfused, the measured temperature can be expected to be below the hottest tissue temperature. Due to the variability in blood vessel size and shape, the relationship between the measured temperature and the hottest tissue temperature or ablation volume will vary. However, a measured temperature above the temperature limit may be an indication of excessive power. The temperature limit can be considered a safety control where temperatures exceeding the limit need to be reduced. However, if the measured temperature is below the limit, it is not necessarily an indication of low tissue temperature. If the measured temperature is below the temperature limit throughout the total treatment time, the RF power remains at the initial power. If during the treatment (total treatment time) t TOTALDuring this period, or optionally before the minimum treatment time is completed, one of the measured temperatures is higher than or optionally equal to the temperature limit T. L Preferably, for such Figure 19 The power can be reduced to a secondary power P2 for the active electrode shown, or alternatively for the electrode or all electrodes associated with the measured temperature. The measured temperature is expected to drop below the temperature limit within approximately 5 seconds (or approximately 2 to 3 pulse widths) of power reduction; however, if the measured temperature does not drop below the temperature limit before the completion of the total treatment time (or optionally the minimum treatment time), or if the measured temperature drops below the temperature limit but then rises again to or above the temperature limit, then preferably for all electrodes, or alternatively for the active electrode or the electrode associated with the measured temperature, the power can be reduced to a low level of 0 W or less than 1 W. Alternatively, the power can be reduced to a tertiary power level, and so on. After the completion of the minimum treatment time, if any measured temperature reaches or exceeds the temperature limit, the power can be reduced to a low level of 0 W or less than 1 W instead of titrating the power to a lower ablation level.

[0276] Optionally, the ablation mode algorithm can also have an impedance limit Z. L The impedance, which can be in the range of 200 to 500 ohms, preferably 500 ohms, can indicate tissue dehydration. If the unipolar impedance measured from one of the multiple electrodes electrically connected to the grounded plate rises above the impedance limit, delivery of ablation energy to the associated electrode can be terminated to avoid vapor formation or injury. Optionally or additionally, if the impedance limit is exceeded before the minimum treatment time is completed, the power of the ablation RF energy can be reduced to a secondary power or, optionally, to other lower power levels in the event of subsequent occurrences. Figure 19 As shown, if the impedance of all electrodes remains within the impedance limit Z... L Below, and at the critical impedance lower limit Z CL Therefore, the power of each electrode will not change.

[0277] Optionally, if the temperature or impedance of a particular electrode is above a temperature limit or impedance limit while delivering secondary power, the ablation RF power may preferably be reduced to 0W for the active electrode or alternatively for the electrode associated with the sensor or for all electrodes.

[0278] Optionally, if the power has been reduced to a secondary power level, the total treatment time or minimum treatment time (if included) may be extended, or optionally, a subsequent lower power level may be used, for example, to match the amount of energy being delivered if the power has not been reduced.

[0279] In addition to temperature and impedance limits, the algorithm can have a critical temperature upper limit T. CUCritical lower limit T CL Critical impedance upper limit Z CU and the lower limit of critical impedance Z CL Critical temperature upper limit T CU It can be used to identify damaged temperature sensors or where a final tissue temperature higher than that is not desired, and can be equal to or higher than 105°C. Critical lower limit T CL It can indicate incorrect placement or equipment malfunction, and can be equal to or below body temperature (e.g., 35°C). Critical impedance upper limit Z CU It can be used to identify conduit damage, such as broken wires or improper grounding plate application, and is available in the range of 800 to 2000 ohms. Critical impedance lower limit Z CL It can be used to identify damage to the catheter, such as short circuits or electrode damage, and can be equal to or less than 20 ohms.

[0280] Optionally, the energy delivery algorithm may have a bipolar RF component, where RF current flows from a first electrode to a second electrode (bipolar mode). Bipolar RF concentrates the current density between the two electrodes, which can result in an ablation pattern where the tissue heated between the electrodes is greater than that delivered independently by the two electrodes delivering monopolar RF. The bipolar RF component can be added at the beginning or end of a multiplexed monopolar RF session. For example, the bipolar RF component may have a duration in the range of 30 s to 120 s, preferably about 60 s, and deliver power at an initial level in the range of 10 to 50 W (e.g., 20 to 35 W, preferably about 30 W), and be delivered before or after multiplexed monopolar RF treatment.

[0281] Alternatively and optionally, the ablation waveform can be similar to a multiplexed monopolar RF algorithm, but with additional pulse widths where the electrodes deliver bipolar RF. For example, the bipolar pulse width can range from 0.5 to 5 s (e.g., 2 s). The waveform can have alternating cycles: for a first pulse width, it is monopolar RF from the first electrode; for a second pulse width, it is monopolar RF from the second electrode; and for repeated bipolar pulse widths, it is bipolar RF between the first and second electrodes. If the ablation catheter has more than two electrodes, the waveform can include repeated cycles of monopolar RF to each electrode for each pulse width and bipolar RF between adjacent pairs of electrodes for each bipolar pulse width.

[0282] An alternative implementation of the ablation energy delivery algorithm for creating desired damage in GSN ablation is referred to as "sequential monopolar with bipolar fill," wherein ablation RF energy is delivered to the first ablation electrode (e.g., in monopolar mode for a first electrode monopolar duration) in monopolar mode. Figure 1 , Figure 2 , Figure 8A, Figure 8B , Figure 9 and Figure 10 The distal electrode 132 shown is then delivered to the second ablation electrode (e.g., the proximal electrode 133) for a second electrode unipolar duration, and then the ablation RF energy is delivered between the first and second electrodes in bipolar mode for a bipolar duration and with an initial bipolar power. If the temperature measured by a temperature sensor associated with the electrode receiving the ablation energy rises above the unipolar temperature limit, the initial unipolar power of the RF energy can be reduced to a secondary unipolar power, or alternatively, a power reduction can be applied. If the temperature rises again above the temperature limit while a lower power is being delivered, the power can be reduced again, or reduced to a tertiary power, or a power reduction can be applied. Optionally, the user can define parameters such as the initial power of each ablation electrode, the first electrode unipolar duration and the second electrode unipolar duration, the power reduction, or secondary, tertiary, etc., unipolar power. Similarly, during the bipolar phase, if the measured temperature from any of the temperature sensors associated with the activated electrode rises above the bipolar temperature limit, the initial bipolar power can be reduced to a secondary bipolar power or a power reduction can be applied.

[0283] Initial unipolar power is the magnitude of the RF power initially delivered to either ablation electrode during the unipolar phase, and is selectable in the range of 20 W to 50 W, with a default setting of 25 W.

[0284] The first electrode unipolar duration is the amount of time it takes for ablation RF energy to be delivered to the first electrode in unipolar mode, and it can be selected in the range of 30 s to 180 s, with the default setting being 60 s.

[0285] The second electrode unipolar duration is the amount of time it takes for ablation RF energy to be delivered to the second electrode in unipolar mode, and it can be selected in the range of 30 s to 180 s, with the default setting being 60 s.

[0286] Secondary monopole power is the magnitude of the RF power below the initial monopole power, triggered by rising to a measurement temperature above the upper temperature limit. It is selectable from 10 W to 50 W as long as it remains below the initial monopole power, with a default setting of 20 W.

[0287] Monopole power reduction is a replacement for secondary monopole power (and optional tertiary monopole power, etc.), and is the amount of power reduction triggered by the rise to a measurement temperature above the upper limit of the monopole temperature. It is selectable in the range of 1 to 20 W, with a default setting of 5 W.

[0288] The initial bipolar power is the magnitude of the RF power initially delivered to the two ablation electrodes (e.g., the two electrodes previously activated with unipolar RF) during the bipolar phase, and can be selected in the range of 10 W to 50 W, with a default setting of 20 W.

[0289] The bipolar duration is the amount of time it takes to deliver ablation RF energy to both electrodes in bipolar mode, and it is selectable in the range of 10 s to 180 s, with a default setting of 20 s.

[0290] Secondary bipolar power is the magnitude of the RF power below the initial bipolar power, triggered by a rise in the measured temperature above the upper limit of the bipolar temperature range. It can be selected from 5 W to 50 W as long as it remains below the initial bipolar power, with a default setting of 15 W.

[0291] Bipolar power reduction is a replacement for secondary bipolar power (and optional tertiary bipolar power, etc.), and is the amount of power reduction triggered by the rise to a measurement temperature above the upper limit of the bipolar temperature. It is selectable in the range of 1 to 20 W, with a default setting of 5 W.

[0292] The upper limit of the unipolar temperature is a threshold temperature to which the unipolar temperature measured during the unipolar phase is compared. It can be selected in the range of 60 to 90°C, with the default setting being 90°C.

[0293] The upper limit of the bipolar temperature is the threshold temperature to which the measured bipolar temperature is compared. It can be selected in the range of 60 to 90°C, with the default setting being 90°C.

[0294] Optionally, if the upper temperature limit is exceeded during the unipolar or bipolar phase, the initial power can be reduced to a secondary power, or the power can be reduced by a decrease, and the duration can be repeated, optionally with the electrode in the same position. If the upper temperature limit is exceeded for an extended period, the treatment may terminate with an error message. The user can then attempt the ablation procedure using a repositioned electrode or a new catheter.

[0295] Optionally, the algorithm may have a unipolar impedance upper limit, which is a threshold impedance to which the measured unipolar impedance is compared during the unipolar phase. This limit is selectable in the range of 150 to 300 ohms, with a default setting of 200 ohms.

[0296] Optionally, the algorithm may have a bipolar impedance upper limit, which is a threshold impedance to which the measured bipolar impedance is compared during the bipolar phase. This limit is selectable in the range of 100 to 300 ohms, with a default setting of 150 ohms.

[0297] The following disclosure provides some exemplary usage methods and their steps. Some implementations of the usage methods may include one or more of the following steps, the order of which may be changed in some cases, and not all of the steps must be performed. The methods described herein may include interventional access, which may include one or more of the following: treating the patient with an anticoagulation therapy regimen suitable for venous interventional procedures; placing a loop electrode in the patient's right chest; performing femoral vein, subclavian vein, or jugular vein puncture, guidewire insertion, and sheath placement using heparinized saline as appropriate according to standard techniques; placing a 0.035 exchange-length guidewire (e.g., Cordis Amplatz Super Stiff 260 cm or equivalent); advancing a 6F universal catheter (e.g., JR4 or equivalent) along the guidewire to the azygos sinus ostium; injecting a pellet of radiopaque contrast agent using the 6F universal catheter to identify the azygos sinus ostium using fluoroscopy; connecting the azygos sinus ostium to the guidewire and the 6F universal catheter, and advancing the guidewire through a valve (if applicable) into the azygos vein; replacing the 6F universal catheter with an azygos vein access sheath, wherein the azygos vein access sheath may be 9F and at least 100 cm long (e.g., Arrow 9F Super Arrow). (Flex guide sheath or equivalent); Position the azygos vein access sheath approximately at the T9 level; Adjust the C-arm off the vertical axis by taking contrast images to obtain the best view of the azygos vein tree before introducing the ablation catheter; Load a 0.014 exchange-length guidewire (e.g., ChoICE Pt LS Floppy or equivalent) into the azygos vein access sheath; and advance the 0.014 guidewire and place it deep into the first target intercostal vein (e.g., T11 intercostal vein).

[0298] The method described herein may include device, generator, and accessory preparation, which may include one or more of the following steps: inspecting the catheter packaging before use; opening the ablation catheter packaging using aseptic techniques; removing the catheter from its packaging and placing it in a sterile area while maintaining sterility; carefully visually inspecting the integrity and overall condition of the electrode and ablation catheter; filling a 10cc or larger syringe with saline and connecting the syringe to the guidewire lumen seat on the ablation catheter handle. Flush the guidewire lumen with saline to remove all air; prepare the ablation catheter by connecting the ablation catheter perfusion tubing to a three-way stopcock, connecting the tubing kit to the three-way stopcock, connecting the saline needle to the suspended sterile saline bag, and ensuring the stopcocks on the saline inlet and outlet tubing are in the open position; insert the perfusion pump tubing into the pump, pass it through the bubble detector, and close the pump door; power on the generator (also known as the computerized console) and initialize the pump; flush the perfusion lumen of the ablation catheter with the pump to pump saline through the perfusion lumen; confirm that the perfusion port is patented; remove air bubbles from the tubing and ablation catheter; observe the saline tubing and catheter tip for air bubbles and continue debubbling until there is no air in the ablation catheter perfusion lumen and tubing kit; to avoid clogging the perfusion catheter and prevent air from entering the ablation catheter, the ablation catheter can be, for example, at 2... Perfusion is continuously performed at a rate of mL / min; perfusion is stopped only after the ablation catheter is removed from the body; user-selectable ablation parameters on the generator are confirmed; the ablation catheter is inserted into the RF generator using a cable; connector polarity is observed; The method described herein may include ablation catheter insertion and ablation energy delivery, which may include one or more of the following steps: inserting a 0.014 guidewire deep into a first target intercostal vein and advancing the ablation catheter into the intercostal vein along the guidewire; once the ablation catheter is inserted into the patient, initiating saline tracking from a generator (examples of which are described herein); guiding the ablation catheter from a peripheral vessel to the desired location using fluoroscopy; the saline infusion rate of the ablation catheter may be increased to a maximum of 50. Initiate the device at a rate of mL / min to access the target intercostal vein; place the proximal marker at the anterior midline of the vertebra in the AP view (if possible); if the azygos vein to the intercostal sinus ostium is located to the right of the patient's midline, advance the device so that the proximal radiopaque marker is located in the azygos vein proximal to the intercostal sinus ostium and approximately at the patient's midline; rotate the C-arm to RAO30 (or an appropriate angle that maximizes the projected length between the proximal and distal radiopaque markers) and confirm that the distal marker does not pass through the costovertebral joint, and adjust accordingly; confirm that both electrodes on the generator show effective impedance readings (e.g., in the range of 80-150 ohms in monopolar mode or 60-80 ohms in bipolar mode); activate a saline infusion rate of 15 ml / min to 30 ml / min before initiating ablation energy delivery; the recommended saline infusion rate during ablation can be 15 ml / min; the saline infusion rate can be adjusted to 15 ml / min to 30 ml / min after RF delivery is initiated. Within ml / min; initiate the RF ablation mode algorithm from the generator; monitor the impedance display on the RF generator before, during, and after RF power delivery; manually stop power delivery if a sudden increase in impedance not exceeding the preset limit is noticed during RF delivery; clinically assess the situation; if necessary, remove the ablation catheter and inspect for damage; in the event of steam burst or automatic shutdown, stop RF and remove the ablation catheter, terminate saline tracking of the RF generator, and perform a visual inspection to check for coagulation, carbonization, or other catheter defects; confirm the saline infusion rate and flush the port before reinsertion into the patient, resuming saline tracking once reinserted; if the ablation catheter is defective, replace it. Replace with a new catheter; reposition the ablation catheter and attempt another RF application; optionally, no more than two 180s RF applications should be performed at a single target site; if the pump alarms and stops perfusion, immediately remove the catheter from the patient, examine and re-flush the ablation catheter; when ablation in the first target intercostal vein (e.g., T11) is complete, remove the guidewire and ablation catheter from the first target intercostal vein and keep them in place in the azygos vein access sheath; the saline perfusion rate of the ablation catheter can be increased to a maximum of 50 cc / min to assist in the removal of the device from the target intercostal vein; the ablation catheter can be removed for examination; deliver contrast agent to visualize the second target intercostal vein (e.g., T10) from the azygos vein access sheath;Repeat the ablation catheter insertion and ablation energy delivery steps to advance the ablation catheter along the guidewire into the second target intercostal vein for ablation; when ablation in the second target intercostal vein is complete, withdraw the ablation catheter back into the 9F azygos vein access sheath and deliver contrast agent from the azygos vein access sheath to obtain fluoroscopic images of the azygos vein tree.

[0299] The method described herein includes device withdrawal, which may include one or more of the following steps: withdrawing the ablation catheter back into the 9F azygos vein access sheath and out of the patient; terminating saline tracking; this will facilitate disconnecting the connector cable; inspecting the ablation catheter; withdrawing the azygos vein sheath from the patient and closing the venous puncture; and disposing of the device after use in accordance with hospital, administrative and / or local government policies.

[0300] In any of the methods described herein, including the ablation confirmation test, not all steps must be performed. Furthermore, some steps may occur in a different order. It is important to note that the surgical procedures described herein are designed to target specific nerves or nerve roots, and to do so from specific target veins, even placing ablation elements or components within certain areas of those veins. The anatomical regions accessed and targeted require specific design requirements. The device design constraints for these approaches differ significantly in other treatments targeting different anatomical locations for placement and targeting different target nerves, and therefore the devices that can be used in these treatments will vary considerably. Therefore, the disclosure herein provides specific reasons for designing particular devices, including the ability to effectively perform the treatments specifically described herein.

[0301] While the foregoing description provides examples of one or more processes or devices, it should be understood that other processes or devices may be within the scope of the appended claims.

[0302] The applicant hereby withdraws and retracts any prior modifications, representations, or other assertions made regarding any existing, prior, or other aspects of the technology (in this document or in any relevant patent application or patent, including any parent patent, family patent, or sub-patent) that might be construed as a waiver of any subject matter supported by this disclosure of this application. The applicant also respectfully notes that any prior art previously considered in any relevant patent application or patent (including any parent patent, family patent, or sub-patent) may require revisiting.

[0303] The specific embodiments described herein are not intended to limit any of the claims, and any claim may cover processes or apparatuses other than those described below, unless expressly indicated otherwise. The claims are not limited to apparatuses or processes having all the features of any of the apparatuses or processes described below, or to features common to multiple or all of the apparatuses described below, unless expressly indicated otherwise. The apparatuses or processes described below may not be embodiments of any proprietary right granted by publication of this patent application. Any subject matter described below and not granted proprietary right by publication of this patent application may be subject matter of another protection document (e.g., a continuation patent application), and the applicant, inventor, or owner does not intend to waive, abandon, or publicly contribute any such subject matter by disclosing it in this document.

[0304] Additional examples 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, comprising: imaging at least a portion of the patient's spine; simultaneously delivering a device to the patient's azygos vein in an intravascular manner; and performing at least one of the following: injecting a radiopaque contrast agent (e.g., dye) from the device into the patient's vascular system (e.g., into the azygos vein and / or one or more intercostal veins) to visualize the position of the vascular system relative to the spine, or identifying the position of at least a portion of the device relative to a portion of the spine, thereby characterizing (e.g., defining and / or quantifying) the position of the patient's azygos vein relative to a portion of the spine (e.g., relative to the midline of the spine).

[0305] In this first additional example, imaging may include imaging in a front-rear view.

[0306] The first additional example may also include determining the lateral position of the patient's azygos vein relative to the patient's spine, where the patient's azygos vein meets the intercostal veins. The lateral position of the patient's azygos vein can be determined simultaneously with imaging of the patient's azygos vein. Imaging may include radiographic imaging (e.g., fluoroscopy) following the injection of a radiopaque contrast agent (e.g., dye) from the device into the patient's vascular system. Determining the lateral position can be used to determine where to place the ablation catheter relative to the intercostal veins as part of the ablation procedure (optionally ablating the GSN).

[0307] A second additional example is a method that includes assessing the location of the patient's azygos vein to determine whether it is centrally located, right-biased (to the right of the patient's center), or left-biased (to the left of the patient's center). The location of the patient's azygos vein can be assessed simultaneously with imaging of the vein. Imaging may include radiographic imaging (e.g., fluoroscopy). Imaging may include imaging in an anterior-posterior view. Assessing the location can be used to determine where to place the ablation catheter as part of the ablation procedure (optionally for ablation of the GSN).

[0308] In this second additional example, the evaluation step may be used to determine where to place the radiopaque marker of the ablation catheter (optionally, a proximal radiopaque marker), wherein the ablation catheter includes an ablation element distal to the radiopaque marker.

[0309] In this second additional example, the evaluation step is used to determine whether to place a radiopaque marker at the sinus opening where the azygos vein meets the intercostal vein, or at (including substantially at) the midline of the spine.

[0310] In this second additional example, if the evaluation step indicates that the azygos vein is right-biased or centered (including substantially centered), the method may include positioning a radiopaque marker at the sinus ostium where the azygos vein meets the intercostal vein.

[0311] In this second additional example, if the evaluation steps indicate that the azygos vein is left-biased, the method may include positioning a radiopaque marker at or substantially at the midline of the spine (e.g., as determined in an anterior-posterior imaging view).

[0312] In this second additional example, the evaluation step can be used to determine where to place the ablation element (e.g., one or more electrodes) that is part of the ablation catheter.

[0313] In this second additional example, the method may further include assessing the location of the distal radiopaque marker relative to at least one or more of a portion of the spine, ribs, or costovertebral joints. The method may further include: if the assessment indicates that the distal radiopaque marker is located distally, retracting the ablation catheter proximally to indicate that the ablation element is located distally. This method may further ensure that the distal radiopaque marker is not more distal than the costovertebral joint.

[0314] A third additional example is a method for endovascular positioning of an ablation catheter for GSN ablation, comprising: positioning the ablation catheter in one or more of an intercostal vein (e.g., T9, T10, or T11) and an azygos vein, wherein the location of the ablation catheter is selected based on the relative position characterized by a portion of the spine and the location of the azygos vein where it meets the intercostal vein.

[0315] A fourth additional example is a method for characterizing the location of a distal segment of an ablation catheter to facilitate the placement of at least a portion of the ablation catheter in an intercostal vein, comprising: positioning the ablation catheter in the patient's intercostal vein (e.g., T9, T10, or T11 intercostal vein); and determining the location of one or more components of the ablation catheter relative to one or more of the spine, ribs, or costovertebral joints while imaging a portion of the patient, including the intercostal veins and a portion of the spine.

[0316] The fifth additional example is a method as described in any of the claims herein, comprising accessing a venous vascular system at the patient's jugular or femoral vein using an access introduction sheath (e.g., 12F).

[0317] The sixth additional example is a method as described in any of the claims herein, comprising delivering a delivery sheath (e.g., a 9F sheath) to the azygos vein (e.g., delivering it to one or two thoracic vertebrae above the target intercostal space).

[0318] A seventh additional example is a method as described in any of the claims herein, comprising delivering a contrast agent to show the location of the azygos vein and one or more intercostal veins, while simultaneously imaging the azygos vein and one or more intercostal veins.

[0319] Any additional example may include an imaging step that includes imaging in the anterior-posterior direction (e.g., with the C-arm in the AP position).

[0320] Any additional example could include positioning the C-arm at a right front angle.

[0321] Any additional example could include positioning the C-arm at an angle ranging from 20 to 70 degrees, such as 30 to 60 degrees.

[0322] Any additional example may include positioning the C-arm at an angle that maximizes the projected distance between a first position and a second position (e.g., the positions of the proximal radiopaque marker and the distal radiopaque marker) on the ablation catheter.

[0323] Any additional examples may include assessing whether RO markers (e.g., distal RO markers) are located at or near a specific anatomical location (e.g., costovertebral joint).

[0324] Any additional examples may include: if the marker is at or near a specific anatomical location, the ablation procedure (e.g., ablation of tissue) continues. If the marker is not at or near a specific anatomical location, the method may include moving the ablation catheter within the intercostal vein. If the marker is not at or near a specific anatomical location, the method may include generating ablation energy within a proximal ablation element (e.g., a coiled electrode) but not within a distal ablation element (e.g., a coiled electrode).

[0325] An eighth additional example is an ablation catheter sized and configured to allow a distal segment of the ablation catheter to be advanced from the azygos vein into the T9, T10, or T11 intercostal veins and adapted to deliver ablation energy. The ablation catheter includes: an elongated shaft of such length that the distal segment of the catheter can be positioned within the T9, T10, or T11 intercostal vein; and the distal segment includes a conductive flexible ablation element carried by the elongated shaft, the conductive flexible ablation element (which may include more than one ablation element) having a length of 5 mm to 20 mm, and the distal segment having an OD of 1.5 mm to 3 mm (at least in the delivery configuration).

[0326] The ninth additional example is an ablation catheter sized and configured to allow a distal segment of the ablation catheter to be advanced from the azygos vein into the T9, T10, or T11 intercostal veins and adapted to deliver ablation energy, the ablation catheter comprising: an elongated shaft of such length that the distal segment of the catheter can be positioned within the T9, T10, or T11 intercostal veins; and the distal segment comprising a conductive flexible ablation element carried by the elongated shaft.

[0327] In this ninth additional example, the ablation element may include a first ablation element axially spaced from the second ablation element, the first and second ablation elements being carried by a shaft. The first ablation element may have a coiled configuration, and the second ablation element may also have a coiled configuration. The coiled configuration of the first ablation element may be identical to 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 manner.

[0328] In this ninth additional example, the first ablation element may have a different length than the second ablation element.

[0329] In this ninth additional example, the first ablation element may have a different coiling direction than the second ablation element (e.g., left-handed versus right-handed).

[0330] In this ninth additional example, the first ablation element may have a different pitch than the second ablation element.

[0331] In this ninth additional example, the first ablation element may have a different wire thickness than the second ablation element.

[0332] In this ninth additional example, the OD of the distal segment at the location of the first ablation element may be different from the OD of the distal segment at the location of the second ablation element.

[0333] In this ninth additional example, both the first ablation element and the second ablation element may have a cross-sectional outer contour that is curved (e.g., circular) or straight (e.g., rectangular).

[0334] In this ninth additional example, the first ablation element and the second ablation element may be hyperelastic materials such as nitinol.

[0335] In this ninth additional example, the first and second ablation elements may be flexible enough to allow the distal segment to be advanced from the azygos vein into one of the T9, T10, or T11 intercostal veins.

[0336] In this ninth additional example, at least one of the first ablation element and the second ablation element may be made by laser-cutting a tubular element (e.g., a nitinol tube).

[0337] In this ninth additional example, at least one of the first ablation element and the second ablation element may include a mesh or braid.

[0338] In this ninth additional example, at least one of the first ablation element and the second ablation element may be a ring electrode with a length not exceeding 5 mm, and optionally about 3 mm.

[0339] In this ninth additional example, the length of each of the first ablation element and the second ablation element may be from 1 mm to 12 mm, optionally from 2 mm to 12 mm, optionally from 5 mm to 12 mm, optionally from 6 mm to 11 mm, optionally from 7 mm to 10 mm, such as approximately 8 mm.

[0340] In this ninth additional example, the axial spacing between the first ablation element and the second ablation element can be 0 mm-8 mm, such as 0 mm-5 mm, such as 0.5 mm-5 mm, such as 1 mm-4 mm.

[0341] In this ninth additional example, the total axial length of the ablation element can be from 1 mm to 25 mm, optionally from 2 mm to 22 mm, optionally from 5 mm to 20 mm, optionally from 8 mm to 20 mm, optionally from 10 mm to 20 mm, optionally from 10 mm to 18 mm, and optionally preferably from 10 mm to 15 mm.

[0342] In this ninth additional example, the ablation element, and optionally the first and second ablation elements, may have an expandable diameter.

[0343] In this ninth additional example, the ablation element may include a plurality of ablation elements, wherein the first ablation element and the second ablation element may be part of the plurality of ablation elements and may define the plurality of ablation elements as a whole.

[0344] In this ninth additional example, multiple ablation elements can be configured to be independently energized in unipolar mode (using a grounded electrode).

[0345] In this ninth additional example, any two of the multiple ablation elements can be configured to be energized in bipolar mode.

[0346] In this ninth additional example, the catheter may include a temperature sensor disposed between the first ablation element and the second ablation element and carried by a shaft.

[0347] In this ninth additional example, the catheter may also include one or more of a temperature sensor distal to the distal ablation element or a temperature sensor proximal to the proximal ablation element.

[0348] In this ninth additional example, the catheter may include at least one infusion port in fluid communication with an infusion lumen, which may be connected to a fluid source in a proximal region of the ablation catheter. The ablation catheter may also include a second infusion port distal to the proximal ablation element.

[0349] In this ninth additional example, the catheter may include one or more infusion ports between the distal and proximal ends of the distal ablation member, and optionally between the windings of the coiled distal ablation member.

[0350] In this ninth additional example, the catheter may include one or more infusion ports between the distal and proximal ends of the proximal ablation member, optionally between the windings of the coiled proximal ablation member.

[0351] In this ninth additional example, the catheter may include one or more infusion ports beneath any flexible ablation element, such as a distal ablation element and / or a proximal ablation member.

[0352] In this ninth additional example, the catheter may further include a deployable element (optionally expandable) carried by a shaft. The deployable element may be distal to the ablation element, optionally distal to the distal ablation element. The deployable element may be inflatable, and the shaft may include an expansion port within the inflatable deployable element. The deployable element may have a delivery configuration and a deployment configuration with an OD greater than the delivery configuration. The deployable element may have an OD from 3 to 6 mm in the deployment configuration, for example, 4 mm to 6 mm. The OD of the deployable element may be equal to or greater than the OD of the shaft in the distal segment by no more than 0.2 mm. The deployable element may include at least one of the following: a balloon, a corrugated member, or a coated stent or coated stent-like device (e.g., a reinforcing member coated with one or more layers of material).

[0353] In this ninth example, the ablation catheter may further include a proximal deployable element carried by an axis proximal to the ablation element, which may be located proximal to the proximal ablation element. The proximal deployable element may be expandable, and the axis may include an expansion port within the proximal deployable element. The proximal deployable element may have a delivery configuration and a deployment configuration with an OD greater than that of the delivery configuration. The deployable element may have an OD of 4-10 mm in the deployment configuration, and optionally be larger than the OD of the distal deployable member. The OD of the proximal deployable element may be equal to the OD of the axis in the distal segment or be no more than 0.2 mm larger than the OD of the axis in the distal segment. The proximal deployable element may include at least one of the following: a balloon, a corrugated member, or a coated stent or coated stent-like device (e.g., a reinforcing member coated with one or more layers of material).

[0354] In this ninth additional example, the catheter may include a centrally deployable element. The centrally deployable element may include any features of the distal or proximal deployable member herein, including any combination thereof.

[0355] In this ninth additional example, the catheter is configured for transvascular ablation of the GSN. The ablation catheter may include a distal segment comprising the distal 7 cm of the ablation catheter. The ablation element may be adapted to produce ablation in the range of 5 mm to 25 mm in length.

[0356] In this ninth additional example, the distal segment can be adapted to flexibly pass through the bend from the azygos vein to the T9-T11 intercostal vein (e.g., with a radius of curvature of >= 5 mm and an angle of up to 120 degrees).

[0357] In this ninth additional example, the outer diameter of the distal segment (at least in the delivery state) is in the range of 1.5 to 3 mm.

[0358] In this ninth additional example, the ablation catheter may also include a guidewire lumen within an elongated shaft.

[0359] In this ninth additional example, the total length of the ablation element (which may include multiple individual ablation elements) can range from 5 mm to 20 mm, for example, 10 to 15 mm.

[0360] In this ninth additional example, any ablation element may include one or more of the following: 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 expandable balloon (e.g., conductive ink, flexible circuit), a conductive film RF electrode, an RF electrode on an expandable cage or mesh, an ultrasonic ablation transducer, an electroporation electrode, a cryoablation element, or a virtual RF electrode.

[0361] In this ninth additional example, the ablation element can be adapted to deliver ablation energy circumferentially (around the ablation element / radially symmetrically around the blood vessel).

[0362] In this ninth additional example, the catheter may also include a proximal radiopaque marker positioned on the axis proximal to or near the ablation element.

[0363] In this ninth additional example, the catheter may also include a distal radiopaque marker positioned distal to the distal end of the ablation element(s).

[0364] In this ninth additional example, the catheter may include an axial gap between the distal radiopaque marker and the distal end of the ablation element.

[0365] Any method in any of the additional methods may be used with any catheter in the additional examples. Any catheter in the additional examples may be used with the methods described herein or in a manner not described herein.

Claims

1. A computer-executable method adapted to calculate the cumulative volume of fluid delivered to a patient via a catheter, while excluding from the cumulative volume fluid that may have been delivered via the catheter but did not enter the patient's vascular system, the method comprising: Initiate a method to calculate the cumulative volume of fluid that has been delivered from outside the catheter into the patient's body through the catheter; as well as In response to a rejection event indicating that the catheter is not in the patient's body, the method of calculating the cumulative volume of fluid is stopped to avoid the inclusion of fluid volumes that were not delivered to the patient's vascular system in the cumulative volume.

2. The method as described in claim 1, wherein, The exclusion event includes operator actions that cause the method to stop.

3. The method as described in claim 1, wherein, The exclusion events include automatic actions that cause the method to stop.

4. The method of claim 1, wherein, The method for calculating the cumulative volume of a liquid includes multiplying the flow rate by the elapsed time.

5. The method of claim 4, wherein, The flow rate is determined by multiplying the volume of each pulse by the number of pulses per second.

6. The method of claim 1, further comprising, when it is determined that the catheter is not in the patient's vascular system, calculating the cumulative volume of fluid not delivered to the patient's vascular system.

7. The method of claim 1, wherein, The excluded events include impedance measurements or impedance calculations that are out of range or have exceeded the threshold limit.

8. The method of claim 7, wherein, The excluded events include impedance measurements or calculations in unipolar mode that are above 700 to 900 ohms.

9. The method of claim 7, wherein, The excluded events include impedance measurements or calculations of ohms higher than 800 to 3000 ohms, such as higher than 900 ohms.

10. The method of claim 7, wherein, The exclusion events include impedance measurements or calculations in bipolar mode that are above 300 to 600 ohms.

11. The method of claim 7, wherein, The excluded events include impedance measurements or impedance calculations exceeding 900 ohms.

12. The method of claim 1, wherein, The excluded events include impedance measurements or impedance calculations that are above the upper threshold or below the lower threshold.

13. The method of claim 12, wherein, The excluded events include impedance measurements or impedance calculations above 900 in unipolar mode.

14. The method of claim 1, wherein, The method for calculating the cumulative volume of the liquid continues uninterrupted until the exclusion event occurs.

15. The computer-executable method as claimed in claim 1, wherein, The method is stored on the external energy delivery console of the ablation system.

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