Electrosurgical device with sensing capabilities - Patent Application 20070122997

Abstract

The system includes a generator capable of supplying energy for puncturing tissue and a current of a known voltage, the current of the known voltage being capable of passing through the tissue without damaging the tissue. The system also includes a puncture device having an elongate member. The distal tip of the elongate member includes an energy delivery device configured to deliver energy for puncturing and two electrodes configured to deliver the current of the known voltage from one electrode to the other electrode through a material in contact with the distal tip. The system further includes a sensor capable of detecting the value of the current between the two electrodes. The generator includes a generator switch for disabling delivery of energy to the distal tip based on the value of the current detected by the sensor.

Description

[Technical Field]

[0001] The present disclosure relates to a surgical perforation device configured to deliver energy and electrical current to biological tissue, where the delivery of energy is controlled by changing electrical current characteristics. More specifically, the present invention relates to a device and method for forming a perforation in the interatrial septum or parietal pericardium while simultaneously using the change in electrical current characteristics as the device moves into the left atrium (if puncturing the interatrial septum) or pericardial cavity (if puncturing the parietal pericardium) to automatically stop the delivery of energy to the punctured tissue once the puncture is complete. Summary of the Invention

[0002] During transseptal puncture procedures, there is a risk of inadvertent puncture of other tissues in the heart after the perforation is formed, resulting in potentially serious complications such as general tissue damage within the left atrium, assist device damage (i.e., damage to pacemaker leads located within the atrium), or cardiac tamponade or accidental aortic puncture. Similar issues are faced in procedures requiring epicardial access, where accidental damage to the myocardium can occur if the puncture into the parietal pericardium is extended further than desired. These issues can be addressed with novel radiofrequency puncture devices that automatically stop the delivery of radiofrequency energy after the puncture device completes puncture of the target tissue and enters the desired anatomical space (e.g., the left atrium or pericardial cavity). As used herein, parietal pericardium refers to the two outer layers of the pericardium, including both the fibrous pericardium as well as the parietal layer.

[0003] The disclosed device, system, and method can be used for other procedures. For example, the disclosed system and method can be used for a TIPS procedure, in which the tissue to be punctured is liver tissue between the liver's inflow portal vein and outflow hepatic vein, the anatomical space into which the device enters after puncture is the inflow portal vein, and the substance (fluid or tissue) into which the device enters after puncture is blood. The delivery of radiofrequency energy is automatically stopped after the puncture device completes perforation of the target tissue (liver tissue between the inflow portal vein and outflow hepatic vein) and enters the desired anatomical space (the inflow portal vein).

[0004] Other examples in which the disclosure and system can be used are listed below. In the following examples, the delivery of radio frequency energy is automatically stopped after the puncture device has completed puncturing the target tissue and entered the desired anatomical space. In a Potts Shunt procedure, the tissue to be punctured is the tissue between the left pulmonary artery and the descending aorta, the anatomical space the device enters after puncturing is the descending aorta, and the material (fluid or tissue) the device enters after puncturing is blood. In procedures involving accessing a blood vessel, the tissue to be punctured is the blood vessel wall, the anatomical space the device enters after puncturing is the blood vessel (or target blood vessel), and the material (fluid or tissue) the device enters after puncturing is blood. In a typical procedure for creating a shunt, the tissue to be punctured is a substance between two parts (or anatomical structures) of the body, the anatomical space into which the device enters after puncture is the target anatomical structure, and the substance (fluid or tissue) into which the device enters after puncture is a substance contained inside the target anatomical structure. In a procedure for transcaval access in TAVR, the tissue to be punctured is a tissue between the abdominal aorta and the adjacent inferior vena cava (IVC), the anatomical space into which the device enters after puncture is the abdominal aorta, and the substance (fluid or tissue) into which the device enters after puncture is blood.

[0005] In a first broad aspect, embodiments of the present invention include a lancing device for use with a generator capable of providing energy for puncturing tissue and a current of known voltage that can pass through the tissue without damaging it. The lancing device includes an elongate member having a proximal portion and a distal portion. The proximal portion is configured to be connected to the generator so that the energy for puncturing tissue and the current of known voltage are provided to the elongate member. The distal portion terminates at a distal tip, the distal tip including an energy delivery device and two electrodes, the energy delivery device configured to deliver energy for puncturing, the two electrodes configured to deliver the current of known voltage through a material in contact with the distal tip, a first of the two electrodes delivering the current to the material and the current returning to the lancing device through a second of the two electrodes. In an exemplary embodiment of the first broad aspect, the proximal portion of the elongate member includes a hub through which the proximal portion is connected to the generator.

[0006] In some embodiments of the first broad aspect, the lancing device further comprises a sensor capable of detecting a value of a current between the two electrodes associated with a current flowing through a material in contact with the distal tip, and the lancing device has means for communicating the value associated with the current between the two electrodes to the generator. In some other embodiments of the first broad aspect, the lancing device further comprises means for communicating the first electrode current parameter and the second electrode current parameter to the generator.

[0007] In features of the first broad aspect, some embodiments include a sensor configured to detect impedance. Some embodiments of the lancing device include a sensor configured to detect dielectric. In some embodiments, the elongate member is a flexible wire. In some other embodiments, the elongate member is a needle.

[0008] In some embodiments of the first broad aspect, the two electrodes are located on a distal surface of the lancing device. Exemplary embodiments further include an insulating material that electrically isolates the two electrodes from the energy delivery device. In some examples, the two electrodes are located laterally opposite each other on a side of the distal tip.

[0009] In a second broad aspect, an embodiment of the present invention includes a system including a generator capable of providing energy for puncturing tissue and a current of a known voltage that can pass through the tissue without damaging the tissue. The system also includes a lancing device, the lancing device including an elongated member having a proximal portion and a distal portion. The proximal portion of the elongated member is configured to connect to the generator so that the energy for puncturing tissue and the current of the known voltage are provided to the elongated member. The distal portion of the elongated member terminates at a distal tip, the distal tip including an energy delivery device configured to deliver energy for puncturing and two electrodes configured to deliver the current of the known voltage through a material in contact with the distal tip, the first of the two electrodes delivering the current to the material and the current returning to the lancing device through the second of the two electrodes. The system further includes a sensor capable of detecting a value of a current between the two electrodes that is associated with the current flowing through the material in contact with the distal tip. The generator includes a generator switch for disabling the supply of energy for puncture to the energy delivery device at the distal tip based on the value of the current detected by the sensor. In an exemplary embodiment of the second broad aspect, the proximal portion of the elongate member includes a hub through which the proximal portion is connected to the generator.

[0010] In some embodiments of the second broad aspect, the lancing device includes a sensor capable of detecting a value of a current between the two electrodes associated with a current flowing through a material in contact with the distal tip, and the lancing device has means for communicating the value associated with the current between the two electrodes with the generator switch. In some other embodiments of the second broad aspect, the generator includes the sensor, and the lancing device includes means for communicating the first electrode current parameter and the second electrode current parameter with the sensor.

[0011] As a feature of the second broad aspect, in some embodiments, the generator switch is a hardware switch. In some other embodiments, the generator switch is a software algorithm. An exemplary embodiment of the second broad aspect includes a generator that delivers energy for puncturing tissue in pulses, wherein a current of known voltage is delivered to two electrodes between the pulses of energy for puncturing.

[0012] In some embodiments of the second broad aspect, the generator switch disables delivery of energy for the lancing when the value detected by the sensor is a value associated with blood, hi some other embodiments, the generator switch disables delivery of energy for the lancing when the value detected by the sensor is less than a threshold value and the threshold value is between the value associated with blood and the value associated with tissue.

[0013] In a third broad aspect, an embodiment of the present invention is a method of accessing the left atrium, comprising: (i) gaining access to the vasculature through the groin to the femoral vein; (ii) inserting a guidewire into the femoral vein; (iii) advancing the guidewire up the inferior vena cava into the right atrium and into the superior vena cava; (iv) advancing a needle-equipped puncture device, dilator, and sheath assembly using the guidewire as a guide rail and removing the guidewire; (v) manipulating the assembly so that, with the distal tip of the puncture device slightly protruding from the distal tips of the dilator and sheath, the distal tip of the puncture device is positioned over the fossa ovalis of the septum and the energy delivery device and two electrodes on the distal tip of the puncture device are in contact with tissue of the fossa ovalis; and (vi) turning on a generator and delivering pulses of energy through the energy delivery device to puncture the tissue. (vii) during the pulse of energy of step (vi), delivering a current of known voltage through the tissue of the fossa ovalis between two electrodes at the distal tip of the puncture device, the current exiting the puncture device through a first of the two electrodes and returning to the puncture through a second of the two electrodes; (viii) upon completing the puncture, advancing the puncture device from the right atrium to the left atrium, whereby the distal tip of the puncture device is no longer in contact with the tissue of the fossa ovalis and there is a change in the value of an electrical characteristic of the current between the electrodes at the distal tip of the puncture device, the change in the electrical characteristic indicating that the distal tip of the puncture device is no longer in contact with the tissue of the fossa ovalis; and (ix) detecting the change in the value of the electrical characteristic via the sensor and ceasing delivery of energy to puncture the tissue by the generator.

[0014] As a feature of the third broad aspect, exemplary embodiments include the electrical property being impedance or dielectric. Some embodiments of the method further include the step (x) of advancing a dilator and a sheath over the puncture device into the left atrium, removing the dilator and the puncture device, and delivering an assist device through the sheath into the left atrium.

[0015] In a fourth broad aspect, an embodiment of the invention is a method of accessing the left atrium, comprising: (i) gaining access to the vasculature through the groin to the femoral vein; (ii) inserting a puncture device comprising a flexible wire into the femoral vein; (iii) advancing the puncture device up the inferior vena cava into the right atrium and into the superior vena cava; (iv) advancing a dilator and sheath assembly using the puncture device as a guide rail; (v) manipulating the assembly so that, with the distal tip of the puncture device slightly protruding from the distal tips of the dilator and sheath, the distal tip of the puncture device is positioned over the fossa ovalis of the septum and the energy delivery device and two electrodes on the distal tip of the puncture device are in contact with tissue of the fossa ovalis; and (vi) turning on a generator and delivering a pulse of energy through the energy delivery device to the tissue of the fossa ovalis to puncture the tissue. (vii) during the pulse of energy of step (vi), delivering a current of known voltage between two electrodes at the distal tip of the puncture device through tissue of the fossa ovalis, the current exiting the puncture device through a first of the two electrodes and returning to the puncture through a second of the two electrodes, (viii) upon completing the puncture, advancing the puncture device from the right atrium to the left atrium, whereby the distal tip of the puncture device is no longer in contact with tissue of the fossa ovalis and there is a change in the value of an electrical property of the current between the electrodes at the distal tip of the puncture device, the change in the electrical property indicating that the distal tip of the puncture device is no longer in contact with tissue of the fossa ovalis, and (ix) detecting the change in the value of the electrical property via the sensor and ceasing delivery of energy to puncture the tissue by the generator. In an exemplary embodiment, the electrical property is impedance or dielectric.

[0016] Some embodiments of the fourth broad aspect further include a step (x) of advancing a dilator and a sheath over the puncture device into the left atrium, removing the dilator and the puncture device, and delivering an assist device through the sheath into the left atrium.

[0017] In order that the invention may be more readily understood, embodiments thereof are shown by way of example in the accompanying drawings, in which: FIG. [Brief explanation of the drawings]

[0018] [Figure 1] 1 shows a perspective view of a medical device according to one embodiment of the present invention. [Figure 2A] 1 shows a partial perspective view of a distal region of an embodiment of a medical device. [Figure 2B] 1 shows a partial perspective view of a distal region of an embodiment of a medical device. [Figure 2C] 1 shows a partial perspective view of a distal region of an embodiment of a medical device. [Figure 2D] 1 shows a partial perspective view of a distal region of an embodiment of a medical device. [Figure 2E] 1 shows a cross-sectional view of a distal region of one embodiment of a medical device. [Figure 3A] 1A-1C show perspective views of various electrode configurations. [Figure 3B] 1A-1C show perspective views of various electrode configurations. [Figure 3C] 1A-1C show perspective views of various electrode configurations. [Figure 3D] 1A-1C show perspective views of various electrode configurations. [Figure 4a] 1A-1C show partial cutaway side and end views, respectively, of a medical device and a tubular member according to one embodiment of the present invention. [Figure 4b] 1A-1C show partial cutaway side and end views, respectively, of a medical device and a tubular member according to one embodiment of the present invention. [Figure 5a] 1A-1C show partially cutaway side and end views, respectively, of a medical device and a tubular member according to another embodiment of the present invention. [Figure 5b] 1A-1C show partially cutaway side and end views, respectively, of a medical device and a tubular member according to another embodiment of the present invention. [Figure 5c] 10A-10C show end views of a medical device and a tubular member according to an alternative embodiment of the present invention. [Figure 5d] 10A-10C show end views of a medical device and a tubular member according to an alternative embodiment of the present invention. [Figure 6a]10A-10C show partial cutaway side and end views, respectively, of a tubular member according to another embodiment of the present invention. [Figure 6b] 10A-10C show partial cutaway side and end views, respectively, of a tubular member according to another embodiment of the present invention. [Figure 7a] 1A-1C show partially cutaway side and end views, respectively, of a medical device and a tubular member according to another embodiment of the present invention. [Figure 7b] 1A-1C show partially cutaway side and end views, respectively, of a medical device and a tubular member according to another embodiment of the present invention. [Figure 8] 1 shows a perspective view of a system including a medical device according to the present invention. [Figure 9a] 1 shows a partial cutaway view of a method of using the device, according to one embodiment of the present invention. [Figure 9b] 1 shows a partial cutaway view of a method of using the device, according to one embodiment of the present invention. [Figure 10A] 2 shows a perspective view of an elongate member portion of the medical device shown in FIG. 1. [Figure 10B] 2 shows a partial perspective view of an alternative elongate member that can be used in the medical device shown in FIG. 1. [Figure 10C] 1. FIG. 4 shows a partial perspective view of another alternative elongate member that can be used in the medical device shown in FIG. [Figure 10D] 1. FIG. 4 shows a partial perspective view of yet another alternative elongate member that can be used in the medical device shown in FIG. [Figure 11A] 10 illustrates a perspective view of a medical device according to yet another alternative embodiment of the present invention, the medical device including a curved section. [Figure 11B] 10 illustrates a partial perspective view of a medical device according to yet another alternative embodiment of the present invention, the medical device including an alternative curved section. [Figure 11C] 10 illustrates a partial perspective view of a medical device according to yet another alternative embodiment of the present invention, the medical device including another alternative curved section. [Figure 12A] 1 illustrates a top elevation view of one embodiment of a hub. [Figure 12B] 12B shows a cross-sectional side view taken along line 5B-5B of FIG. 12A. [Figure 13A]1 shows a device suitable for puncturing tissue with an automatic shutoff feature. [Figure 13B] 13a shows a cutaway view of one embodiment of the device with a hollow conductive tube. [Figure 13C] 13a shows a cutaway view of one embodiment of the device with flexible wires. [Figure 14A] 1 illustrates one example of the placement of an energy delivery device and monitoring electrodes on the distal tip of a lancing device. [Figure 14B] 10 illustrates another embodiment of the placement of the energy delivery device and monitoring electrodes on the distal tip of the lancing device. [Figure 14C] 10 illustrates yet another embodiment of the placement of the energy delivery device and monitoring electrodes on the distal tip of the lancing device. [Figure 15A] 10 shows one example of the placement of monitoring electrodes on the side of the distal tip of the lancing device. [Figure 15B] 15b shows the lancing device of FIG. 15a in contact with tissue. [Figure 16] FIG. 1 shows a circuit diagram illustrating current flow for automatic shutdown using impedance. [Figure 17A] 17 shows an algorithm for energy blocking that can be used with the embodiment of FIG. [Figure 17B] 17 illustrates another algorithm for energy blocking that can be used with the embodiment of FIG. [Figure 18] FIG. 1 shows a circuit diagram illustrating current flow for automatic shutdown using inductivity. [Figure 19A] 19 shows an algorithm for energy blocking that can be used with the embodiment of FIG. 18. [Figure 19B] 19 illustrates another algorithm for energy blocking that can be used with the embodiment of FIG. 18. [Figure 20] 1 illustrates an embodiment of a system for puncturing tissue with an automatic shutoff. DETAILED DESCRIPTION OF THE INVENTION

[0019] Certain medical procedures require the use of medical devices capable of forming a puncture or channel through tissue. Specifically, puncturing the septum of the heart creates a direct pathway to the left atrium, where many cardiac procedures are performed. One such device for gaining access to the left atrium is a transseptal puncture device, which, in some devices, delivers radio frequency energy from a generator into tissue to create a puncture. The user places the puncture device at a target location on the fossa ovalis, located on the septum of the heart, turns on the generator, and begins delivering energy to the target location. The delivery of radio frequency energy to the tissue causes evaporation of intracellular fluid in cells in contact with the energy delivery device. Ultimately, this creates a void, hole, or channel at the target tissue site.

[0020] During the transseptal puncture procedure, there is a risk of inadvertent puncture of other cardiac tissues after the septal perforation is formed, resulting in general tissue damage within the left atrium, assist device damage (i.e., damage to pacemaker leads located within the atrium), or potentially serious complications such as cardiac tamponade or accidental aortic puncture. Cardiac tamponade is a life-threatening complication of transseptal puncture that occurs when a perforation is formed in the left atrial wall, left atrial roof, or left atrial appendage. This perforation of the atrial wall leads to the accumulation of fluid in the pericardial space around the heart. This fluid accumulation compresses the heart, thereby reducing the amount of blood available to enter the heart. Accidental aortic puncture is a rare, life-threatening complication in which the puncture device enters and punctures the aorta, which may require surgical repair.

[0021] A similar problem is encountered in procedures requiring epicardial access, where accidental damage to the myocardium can occur if the puncture into the parietal pericardium is extended further than desired. In such procedures, myocardial damage can be prevented by ceasing delivery of radiofrequency energy after the puncture device has entered the pericardial space.

[0022] In consideration of these complications associated with inadvertent puncture, the inventors have devised and reduced to implementing embodiments of an electrosurgical device in which the delivery of radio frequency energy is automatically stopped after the puncture device completes the puncture and enters the left atrium or pericardial cavity. In some cases, a radio frequency (RF) energy source is used to selectively apply RF energy to tissue. Exemplary embodiments of the device include insulation to protect the user and patient and are configured to avoid embolic generation.

[0023] While specific reference will now be made to the drawings in detail, it should be noted that the details shown are by way of example and are intended only for the purpose of illustratively describing embodiments of the invention. In this regard, no attempt has been made to show structural details of the invention in more detail than is necessary for a fundamental understanding of the invention. The description in conjunction with the drawings will make apparent to those skilled in the art how certain aspects of the invention can be embodied in practice.

[0024] Before describing at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments or of being practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting.

[0025] As used herein, the terms "proximal" and "distal" are defined relative to the user. That is, when the device is in use, the term "proximal" refers to the part or portion closer to the user, and the term "distal" refers to the part or portion farther from the user. Also, for clarity, the terms tubular or tubular member are used to describe members that surround the disclosed medical devices, but it should be noted that the term tubular member is intended to describe both circular and non-circular embodiments of the surrounding member. The term tubular member is used in this disclosure to describe dilators, sheaths, and other members that define a lumen for housing the medical device.

[0026] 1, a medical device 100 according to one embodiment of the present invention is shown. The medical device 100 can be used to form a channel at a target location within a patient's body. The medical device 100 includes a handle 110, a distal portion 112, and a force transmission portion 114 extending between the distal portion 112 and the handle 110. The distal portion 112 defines a distal portion length and includes an electrode 106 and an electrical insulator 104 extending proximally from the electrode 106.

[0027] The force transmission portion 114 defines a force transmission portion length, the force transmission portion length being greater than the distal portion length. In some embodiments of the invention, the force transmission portion 114 has a force transmission capacity of at least about 0.016 Nm 2 , for example, about 0.017 Nm 2 The force transfer portion 114 has a force transfer portion bending stiffness of 0.05 mm. The force transfer portion 114 has a force transfer portion bending stiffness that allows a contact force applied to the distal portion 112 to be transferred to the handle 110 when the distal portion 112 contacts a target location to provide tactile feedback to the intended user. Additionally, the force transfer portion bending stiffness allows for the transfer of force from the handle 110 to the distal portion 112, for example, to advance the distal portion 112 within a patient's body or to orient the distal portion 112 by applying a torque to the handle 110.

[0028] Thus, the proposed medical device 100 is constructed to provide an intended user with a similar or better "feel" than some prior art devices, i.e., the structure and function of the medical device 100 are significantly different from prior art devices.

[0029] In some embodiments of the present invention, the distal portion 112 has a resistance of at least about 0.0019 Nm 2 , e.g. 0.0021 Nm 2 Such values ​​of bending stiffness improve the perceived ergonomics of the proposed medical device 100 by providing tactile feedback to the intended user and allowing for the transmission of radial (torque) and longitudinal forces from the handle to the distal portion.

[0030] In an exemplary embodiment of the invention, medical device 100 includes an electrically conductive elongate member 102 having an electrical insulator 104 disposed thereon. Electrical insulator 104 covers substantially the entire outer surface of elongate member 102 such that elongate member 102 is capable of delivering energy from its proximal region to electrodes 106 at its distal region without substantial leakage of energy along the length of elongate member 102. Elongate member 102 defines a lumen 208 and at least one side port 600 (shown, for example, in FIGS. 2A-2D ) in fluid communication with lumen 208.

[0031] The one or more side ports 600 are particularly useful in exemplary embodiments of the medical device 100 in which the lumen 208 of the elongate member 102 is not open to the surrounding environment through the distal end of the medical device 100 (i.e., the medical device 100 is a closed-end device), such as the embodiment of Figures 2A-2E. In such embodiments, the lumen extends substantially longitudinally through the force transfer portion 114 (Figure 1) and through a section of the distal portion 112, terminating at the distal portion 112 at a location substantially spaced from the distal tip 403 such that the distal tip 403 remains closed.

[0032] In embodiments including side port(s) 600, the side port(s) 600 allow fluid to be infused from the lumen 208 to the surrounding environment and / or allow pressure to be measured by providing a pressure transmission lumen through the medical device 100. In some examples, the side port(s) 600 are formed radially through the elongate member 102 and the electrical insulator 104, thereby allowing fluid communication between the surrounding environment and the lumen 208. In an alternative embodiment, the side port 600 is formed radially through a portion of the electrode 106.

[0033] The size and shape of the side port(s) 600 may vary depending on the intended use of the medical device 100, and the invention is not limited in this regard. For example, in one embodiment, the side port(s) 600 are about 0.25 mm to about 0.45 mm in diameter. Some embodiments include two or more sizes of side ports. Additionally, the number of side ports 600 may vary, and the side ports 600 may be located anywhere along the medical device 100 that does not interfere with the function of the device. For example, as shown in FIG. 2A, the medical device 100 includes two side ports 600 located at substantially the same longitudinal position along the elongate member 102, approximately 1 cm from the distal end of the elongate member 102. In another embodiment, as shown in FIG. 2B, the medical device 100 includes approximately three side ports located at the same circumferential position and spaced longitudinally apart from the distal end of the elongate member 102 by approximately 1.0 cm, 1.5 cm, and 2.0 cm. In another embodiment, the side ports 600 are staggered so that they are spaced both circumferentially and longitudinally, as shown in FIG. 2C. In a further embodiment, the side ports 600 are located on the electrode 106, as shown in FIG. 2D. In some embodiments, the side port(s) 600 have smooth or rounded walls, which serve to minimize or reduce trauma to body tissue. For example, some such embodiments include one or more side port(s) 600 with a smooth outer circumferential edge formed by polishing the circumferential edge to a smooth finish or, for example, by coating the edge with a lubricious material.

[0034] When a medical device that relies on a side port to provide fluid communication between its lumen and the surrounding environment is inside the lumen of the seal-fitting member, the side port can be partially or completely occluded or blocked. The embodiments of Figures 4-9 relate to devices that provide an effective conduit from the lumen of a medical device to the environment outside the device, and methods of using such devices.

[0035] 4a and 4b show partially cutaway side and end views, respectively, of distal portion 112 of medical device 100 disposed within tubular member 800. As described in more detail herein below, some embodiments of medical device 100 are comprised of a single elongate member 102 (as shown in FIGS. 1 and 10A), while some other embodiments of medical device 100 are comprised of two elongate members, a main member 210 and an end member 212, joined together (as shown in FIGS. 10D and 2E). Depending on the embodiment of medical device 100 under consideration, distal portion 112 may be the distal portion of the single elongate member 102, the distal portion of end member 212, or the distal portion of some other embodiment of medical device 100. In FIGS. 4-9, the lumen defined by distal portion 112 may be either lumen 208 of elongate member 102 or end member lumen 216. For purposes of explanation, the lumen defined by distal portion 112 in FIGS. 4-9 will be referred to as device lumen 809.

[0036] The tubular member 800 may include a dilator, a sheath, or any other member defining a lumen configured to receive the medical device 100 . 4a and 4b, the illustrated features of an embodiment of the distal portion 112 of the medical device 100 include a diameter change 831, a distal portion 830, a device lumen 809 defined by the body of the medical device 100, a side port 600 in fluid communication with the lumen, and a closed distal end. The distal portion 830 has an outer diameter that is smaller than the outer diameter of the distal portion 112 proximal to the diameter change 831; i.e., the distal portion 830 has a reduced diameter. In the embodiment of FIG. 4a, the distal tip 403 of the medical device includes a distal electrode 106. Some alternative embodiments of the medical device 100 do not include an electrode. The tubular member 800 defines a tubular member lumen 802. The tubular member 800 and distal portion 830 of the medical device 100 combine to define a conduit 808, which allows the medical device 100 to provide sufficient fluid flow to deliver contrast fluid to stain tissue. Fluid (e.g., blood) may also be drawn through the pathway defined by the conduit 808, the side port 600, and the device lumen 809. In the embodiment of FIG. 4a, the conduit 808 includes the space between the tubular member 800 and the reduced diameter distal portion 830, and the portion of the tubular member lumen 802 distal to the medical device 100.

[0037] In the embodiment of Figure 4a, distal portion 830 is distal to diameter change portion 831 and includes insulator portion 834 and electrode 106. Constant diameter portion 836 is distal to diameter change portion 831 and includes insulator portion 834 and a straight, longitudinal portion of electrode 106 having a constant diameter (i.e., the portion of the electrode proximal to the dome-shaped electrode tip). Constant diameter portion 836 of distal portion 830 can be described as having a substantially constant diameter along its length, rather than being tapered. There is a slight change in outer diameter at the distal end of electrical insulator 104, but this can be considered negligible with respect to fluid flow.

[0038] In the embodiment of FIG. 4a, a small space or gap 832 exists between the tubular member 800 and a portion of the distal section 112 proximal to the diameter change 831. Embodiments of the medical device 100 and tubular member 800 typically have a small gap 832 between the outer diameter of the medical device and the inner diameter of the tubular member. Eliminating the gap entirely could increase friction between the medical device and the tubular member, making it difficult to advance the medical device 100 through the tubular member 800. In typical embodiments, the gap is small enough to prevent substantial flow of fluids, such as contrast fluids, which are typically 3-5 times more viscous than water.

[0039] In the embodiment of FIG. 4a, side port 600 is near diameter change 831, whereby the larger diameter portion of distal portion 112 acts as a brace to keep tubular member 800 from blocking side port 600. FIG. 4a shows an abrupt change in diameter. Alternative embodiments have a less abrupt diameter change. An exemplary embodiment of medical device 100 includes a second side port, with the two side ports being opposite each other. Some alternative embodiments include three or more side ports. Other alternative embodiments have one side port. In some alternative embodiments of medical device 100, side port 600 is longitudinally elongated, i.e., capsule-shaped.

[0040] Together, the side port(s) 600 and the device lumen 809 provide a pressure transmission lumen that is operable to be coupled to a pressure transducer, for example, an external pressure transducer 708 (illustrated in FIG. 8).

[0041] The distal tip 403 of the medical device 100 is shown in the example of FIG. 4a as being slightly proximal to the distal end of the tubular member 800. In this position, fluid communication can be established between the medical device lumen and the surrounding environment. Fluid communication may also be established when the distal tip 403 is positioned further proximal to the distal end of the tubular member 800, when the distal tip 403 is aligned with the distal end of the tubular member 800, and when the distal tip 403 is positioned distal to the distal end of the tubular member 800. If the distal tip 403 is positioned such that the side port 600 is distal to the distal end of the tubular member 800, it is still possible to deliver fluid radially.

[0042] Exemplary embodiments of medical device 100 include an electrically conductive member (elongate member 102 or main member 210 joined to end member 212), which is typically made of a metallic material. The electrically conductive member is in electrical communication with distal electrode 106, and an insulating layer (electrical insulator 104) covers the metallic material. In other words, elongate member 102 includes an electrically conductive material, an insulating layer covers the electrically conductive material, and the electrically conductive material is electrically coupled to electrode 106. In some single embodiments, elongate member 102 has an outer diameter of about 0.7 mm to about 0.8 mm proximal to diameter change 831 at distal end 206, and an outer diameter of about 0.4 mm to about 0.62 mm at reduced diameter distal portion 830. In some two-piece embodiments, end member 212 has an outer diameter of about 0.40 mm to about 0.80 mm proximal to diameter transition 831 and an outer diameter of about 0.22 mm to about 0.62 mm at distal portion 830. The above-described embodiments are typically used with a tubular member defining a corresponding lumen that is about 0.01 mm (0.0005 inches) to about 0.04 mm (0.0015 inches) larger than the outer diameter of medical device 100 proximal to diameter transition 831.

[0043] Figure 4b shows an end view of the device of Figure 4a. The view includes, from inside to outside (in solid lines), electrode 106, electrical insulator 104, a portion of distal section 112 proximal to diameter change 831, gap 832, tubular member distal end 801, and tubular member 800. Hidden features shown in dashed lines include side port 600 and device lumen 809.

[0044] In the embodiment of Figures 4a and 4b, the distal tip 403 of the medical device comprises an electrode 106 that defines a substantially circular cross-section and a circular end profile. Similar to the embodiment of Figures 3A and 3B, the electrode 106 in Figure 4b is at the end of the elongate member 102 (or end member 212) and has the same outer diameter as the distal end of the conductive member. Because the constant diameter section 836 of the reduced diameter distal portion 830 is not substantially tapered (small changes in diameter at the distal end of the electrical insulator 104 are not considered substantial), the electrode 106 has a diameter substantially equal to the diameter of the portion of the distal portion 830 proximal to the electrode 106 (i.e., substantially equal to the diameter of the insulating portion 834).

[0045] 1-4 , some embodiments of the medical device 100 include an elongate member 102 having a closed distal end, the elongate member defining a device lumen 809 and at least one side port 600 in fluid communication with the device lumen. The elongate member also defines a proximal portion and a distal portion 830, the distal portion extending from the at least one side port 600 to the distal end of the elongate member. The proximal portion defines a first outer diameter, and the distal portion defines a second outer diameter, the first outer diameter being larger than the second outer diameter, and the second outer diameter being substantially constant. The distal tip of the medical device 100 includes an electrode 106. The diameter of the electrode is substantially equal to the second outer diameter.

[0046] Some embodiments of the electrode 106 typically form a puncture in tissue having a diameter 10 to 20 percent larger than the electrode. Such a puncture diameter is typically large enough to facilitate passage of the portion of the medical device proximal to the diameter transition 831 (i.e., the larger diameter portion of the medical device) through the tissue puncture and to begin advancing a dilator over the medical device 100 and through the tissue.

[0047] 5a-5d illustrate an embodiment of a medical device 100 in which a distal portion 830 has a non-circular cross-section. In FIGS. 5a and 5b, the distal portion 830 (including the electrode 106 and insulating portion 834 (FIG. 4a)) defines a substantially flat outer surface portion. The body of the medical device 100 defines a device lumen 809 (shown in dashed lines in FIG. 5b) and a side port 600 in fluid communication with the lumen. The reduced outer diameter distal portion 830 of the body extends between the side port 600 and the distal tip 403 of the medical device, whereby the outer surface of the medical device 100, in combination with the tubular member 800, can provide a conduit 808. While FIG. 5a shows the reduced outer diameter distal portion 830 extending proximally from the side port 600 to the diameter change 831, some alternative embodiments do not include this portion, i.e., the diameter change 831 is adjacent to the side port 600.

[0048] The embodiment of conduit 808 in Figure 5b is shown as having an end view shape of a portion of a circle. The reduced outer diameter is substantially constant longitudinally along distal portion 830, except for the distal end of electrical insulator 104 and the hemispherical distal tip of electrode 106. The cross section of electrode 106 is substantially identical to the cross section of the portion of distal portion 830 proximal to the electrode.

[0049] Figure 5c shows an alternative embodiment having two flat outer surfaces and two corresponding side ports. Figure 5d shows another alternative embodiment having three flat outer surfaces and three corresponding side ports. This further alternative embodiment is similar to the embodiments of Figures 5b, 5c, and 5d, except that instead of flat outer surfaces, the device has corresponding outer surfaces that are convexly curved to provide a larger device lumen 809.

[0050] 6a and 6b illustrate one embodiment of a tubular member 800 for use with a medical device 100 having a side port 600. The body of tubular member 800 defines a lumen such that tubular member proximal region 803a has a first inner diameter d1 and tubular member distal region 803b has at least a portion thereof defining a second inner diameter d2, the second inner diameter d2 being larger than the first inner diameter d1, and tubular member distal region 803b extends to tubular member distal end 801.

[0051] The embodiment of Figure 6b includes a tubular member distal region 803b that extends circumferentially for less than 360 degrees around the circumference of the tubular member (i.e., an increased diameter portion having a second inner diameter d2). Tubular member inner surface 804 defines a tubular member channel 805, which extends circumferentially for approximately 90 degrees in the example of Figure 6b. In some alternative embodiments, tubular member distal region 803b extends 360 degrees around the circumference of the tubular body.

[0052] The embodiment of Figures 6a and 6b includes a tubular member proximal marker 816 at the proximal end of the distal region and a tubular member distal marker 818 at the distal end of tubular member distal region 803b. Alternate embodiments have only one of the distal region markers or none of the distal region markers. The embodiment of Figures 6a and 6b also includes a side marker 819 that is operable to be used as an orientation marker for aligning tubular member distal region 803b (i.e., the increased diameter portion) with side port 600 of medical device 100 disposed inside the tubular member.

[0053] One embodiment is a dilator comprising a tubular member defining a lumen in fluid communication with a distal end aperture, a proximal region having a first inner diameter, and a distal region having an increased diameter portion extending proximally from the distal end of the dilator and defining a substantially longitudinally constant second inner diameter greater than the first inner diameter.

[0054] The embodiment of Figures 7a and 7b is a kit including a tubular member 800 and a medical device 100 operable to be combined to form a device. The tubular member 800 defines a tubular member lumen 802 for receiving the medical device 100. The medical device 100 defines a device lumen 809 in fluid communication with the side port 600 and includes a medical device proximal region 838 proximal to the side port and a medical device distal region 839 distal to the side port. The medical device 100 and tubular member 800 are configured to cooperatively form a conduit 808 between an outer surface of the medical device distal region 839 and an inner surface of the tubular member 800. While in the example of Figure 7a, the conduit 808 is formed both proximal and distal to the side port 600, in alternative embodiments, it is formed only distal to the side port. In typical use, the conduit 808 is formed at least between the side port and the distal end of the tubular member when the medical device 100 is inserted and positioned within the tubular member lumen 802 .

[0055] The device of Figure 7a includes both a tubular member channel 805 and a medical device channel 807. Conduit 808 is comprised of both a tubular member channel 805 and a medical device channel 807. In typical embodiments, at least a portion of the length of conduit 808 has a constant cross-sectional configuration, which reduces turbulence and facilitates laminar flow, which in turn facilitates forward injection of fluids. Some alternative embodiments include a tubular member channel 805 but not a medical device channel 807, and some other alternative embodiments include a medical device channel 807 but not a tubular member channel 805.

[0056] Some embodiments of the medical device and tubular member further comprise corresponding markers for aligning the side port of the medical device within the tubular member lumen to form the aforementioned conduit. In the example of FIG. 7, medical device 100 includes medical device proximal marker 810 and medical device distal marker 812, while tubular member 800 includes side marker 819. In some embodiments of the kit, the corresponding markers are configured to longitudinally align the side port within the tubular member lumen. In the example of FIG. 7, side port 600 that is equidistant between medical device proximal marker 810 and medical device distal marker 812 can be longitudinally aligned with side marker 819 by disposing side marker 819 between medical device proximal marker 810 and medical device distal marker 812.

[0057] In some embodiments of the kit, the corresponding marker is configured to rotationally align the side port within the tubular member lumen. In the example of FIG. 7 , the side port 600 can be rotationally aligned with the side marker 819 of the tubular member 800 by comparing the relatively larger diameter medical device proximal marker 810 with the smaller diameter medical device distal marker 812, thereby aligning the side port 600 with the tubular member channel 805. Alternative embodiments of the medical device 100 include a side marker on the same side as the side port 600 or on the opposite side of the side port to facilitate rotational alignment. Further details regarding markers can be found in U.S. Patent No. 4,774,949, issued October 4, 1988 to Fogarty, which is incorporated herein by reference in its entirety.

[0058] One embodiment of the kit includes a tubular member defining a tubular member lumen in fluid communication with a distal end aperture, and a medical device having a closed distal end. The medical device includes a device lumen in fluid communication with at least one side port and a distal portion extending from the at least one side port to the distal end of the medical device. The medical device and the tubular member are configured to cooperatively form a conduit between an outer surface of the distal portion and an inner surface of the tubular member when the medical device is inserted within the tubular member lumen. The conduit extends at least between the side port and the distal end aperture to enable fluid communication between the side port and an environment external to the distal end aperture.

[0059] In a particular embodiment of the kit, end member 212 has an outer diameter proximal to diameter transition 831 of about 0.032 inches (about 0.81 mm) and an outer diameter of reduced diameter distal portion 830 of about 0.020 inches (about 0.51 mm) to about 0.025 inches (about 0.64 mm). End member 212 is used with a tubular member defining a lumen of about 0.0325 inches (0.82 mm) to about 0.0335 inches (0.85 mm).

[0060] Referring to FIG. 8, a system for use with medical device 100 typically includes a generator 700 and, in some embodiments, a grounding pad 702, external tubing 706, a pressure transducer 708, and / or a fluid source 712.

[0061] Referring to FIG. 8 , as described herein above, an external pressure transducer may be coupled to medical device 100 to measure pressure in distal region 202 ( FIG. 10 ) of medical device 100. In the embodiment of FIG. 8 , adapter 705 is operably coupled to external tubing 706, which is operably coupled to external pressure transducer 708. Adapter 705 is structured to couple to adapter 704 during use. In some embodiments, adapters 704 and 705 include male and female Luer lock or other fluid connectors adapted for easy coupling and decoupling from one another. During use, tubing 706 and 708 can be flushed with saline or another suitable fluid to remove air bubbles before measuring pressure. When medical device 100 is placed within a vessel, duct, or body cavity, fluid adjacent distal region 202 (FIG. 10) exerts pressure through side port(s) 600 on fluid within lumen 208, which in turn exerts pressure on fluid within tubing 508 and 706, which in turn exerts pressure on external pressure transducer 708. Side port(s) 600 and lumen 208 thus provide a pressure sensor in the form of a pressure transmission lumen for coupling to a pressure transducer.

[0062] The external pressure transducer 708 generates a signal that varies as a function of the pressure it senses. The external pressure transducer 708 is electrically coupled to a pressure monitoring system 710 that operates to convert the signal provided by the transducer 708 to, for example, display a pressure curve as a function of time. Thus, pressure is optionally measured and / or recorded and used to determine the location of the distal region 202, according to one embodiment of a method aspect described further herein below. In embodiments of the medical device 100 that do not include a lumen in fluid communication with the external environment, the pressure transducer may be attached to or proximate the distal portion 112 of the medical device 100 and coupled to the pressure monitoring system, for example, via an electrical connection.

[0063] As previously mentioned, in some embodiments, the medical device 100 is operably coupled to a fluid source 712 for delivering various fluids to the medical device 100 and thereby to the surrounding environment. The fluid source 712 may be, for example, an IV bag or a syringe. The fluid source 712 may be operably coupled to the lumen 208 via the tubing 508 and the adapter 704, as described herein above. Alternatively, or in addition, some embodiments include the medical device 100 operably coupled to a suction device for removing material from the patient's body through one or more of the side ports 600.

[0064] In one broad aspect, the medical device is used in a method of establishing a conduit for fluid communication for a medical device 100, the medical device defining a device lumen 809 in fluid communication with a side port 600. With reference to Figures 4-9, the method includes the steps of (a) inserting a medical device 100 having at least one side port 600 into a tubular member 800, and (b) cooperatively defining a conduit for fluid communication 808 by positioning the side port 600 of the medical device 100 at a location on the tubular member 800 where a space exists between the side port 600 and an inner surface 804 of the tubular member, the space extending between at least the side port 600 and the distal end of the tubular member.

[0065] In some embodiments of the broad aspect, the medical device comprises a medical device proximal marker 810 proximal to the side port and a medical device distal marker 812 distal to the side port, and step (b) comprises visualizing at least one of the proximal and distal markers to locate the medical device. In some such embodiments, step (b) comprises locating side port 600 within tubular member lumen 802, for example, by using medical device proximal marker 810 and medical device distal marker 812. In such embodiments of the method, distal tip 403 need not be inside tubular member lumen 802. In some embodiments of the method, the medical device further comprises a side port marker, the side port marker and the side port are equidistant from the tip of the medical device, and step (b) comprises visualizing the side port marker to locate the medical device. In some other embodiments, step (b) includes disposing the distal portion 830 of the distal portion 112 within the tubular member lumen 802, which essentially disposes a side port within the tubular member lumen. In some embodiments of the method, step (b) includes aligning the distal tip 403 of the medical device with the tubular member distal end 801.

[0066] Some embodiments of the broad aspect further include step (c) of delivering a fluid through side port 600, the fluid being contrast fluid 814, and step (c) including delivering the contrast fluid distally through the distal end of the tubular member. Some such embodiments further include the step of delivering electrical energy to puncture the tissue before the contrast fluid is delivered. Some embodiments include step (d) of delivering electrical energy through the medical device to form a puncture through the tissue after the contrast fluid is delivered.

[0067] In some embodiments, the tissue comprises a cardiac septum, and step (c) comprises staining the septum by delivering a contrast fluid through a side port. In some embodiments of the broad aspect, the side port 600 and the device lumen 809 together comprise a pressure transmission lumen, and the method further includes step (c) measuring the pressure of the environment external to the distal end using the side port and the conduit. Some such embodiments further include step (d) delivering a fluid through the side port.

[0068] Some embodiments of the broad aspect further include step (c) of withdrawing fluid through side port 600. In some such embodiments, the fluid is blood. In one example of the method of use shown in Figures 9a and 9b, the target site includes atrial septum 822, which is tissue within the patient's heart. In this example, the target site is accessed via the inferior vena cava (IVC), for example, through the femoral vein. The medical device 100 of Figures 9a and 9b is similar to the medical device of Figure 4a, except that the embodiment of Figure 9 includes a medical device proximal marker 810 and a medical device distal marker 812.

[0069] An example of the method includes a user advancing a sheath 820 and dilator (i.e., tubular member 800) through the inferior vena cava 824 and introducing the sheath and tubular member 800 into the right atrium 826 of the heart. An electrosurgical device, such as medical device 100 described herein above, is then introduced into the tubular member lumen 802 and advanced toward the heart. In an exemplary embodiment of the method, these steps are performed using fluoroscopic imaging.

[0070] After inserting medical device 100 into tubular member 800, the user positions the distal end of tubular member 800 against the atrial septum 822 ( FIG. 9 a). Some embodiments of tubular member 800 include markers ( FIG. 6 a). The medical device is then positioned so that electrode 106 is aligned with the distal end of tubular member 800, or slightly proximal to the distal end ( FIG. 9 a inset). Medical device proximal marker 810 and medical device distal marker 812 facilitate positioning of medical device 100. Tubular member 800 is typically positioned against the fossa ovalis of the atrial septum 822. Referring to the inset of FIG. 9 a, the inner surface of tubular member 800 and the outer surface of medical device 100 define a conduit 808 from side port 600 to the distal end of tubular member lumen 802, which is sealed by the atrial septum 822.

[0071] Once the medical device 100 and tubular member 800 are positioned, additional steps can be performed, including taking pressure measurements and / or delivering a substance, such as a contrast agent, to the target site through the side port(s) 600. The inset in FIG. 9a shows contrast fluid 814 flowing from the side port 600 through the conduit 808 and terminating at the atrial septum 822, thereby staining the tissue with the contrast fluid. In an alternative embodiment, the electrode 106 is positioned against the atrial septum 822 as the contrast fluid 814 is delivered. Such steps facilitate localization of the electrode 106 at the desired target site.

[0072] Starting from the position shown by the inset in FIG. 9 a, the medical device 100 is advanced until the electrode 106 contacts the atrial septum 822. (An alternative embodiment in which the electrode 106 is positioned against the atrial septum 822 when the contrast fluid 814 is delivered does not require this repositioning.) With the medical device 100 and dilator (i.e., the tubular member 800) positioned at the target site, energy is delivered from an energy source through the medical device 100 to the target site. The path of energy delivery is through the elongate member 102 (or the main member 210 and end member 212), to the electrode 106, and into the tissue at the target site. The example of FIG. 9 a includes delivering energy to vaporize cells near the electrode, thereby forming a void or puncture through the tissue at the target site, and advancing the distal portion 112 of the medical device 100 at least partially through the puncture. Once the distal portion 112 has passed through the target tissue and reached the left atrium ( FIG. 9 b), energy delivery is stopped. A side port of the medical device 100 is exposed (inset of FIG. 9 b), allowing contrast to be delivered to confirm the location of the distal portion 112 within the left atrium of the heart. The diameter of the puncture created by the energy delivery is typically large enough to facilitate the advancement of the distal portion 112 of the medical device 100 therethrough and to begin the advancement of the dilator (i.e., tubular member 800).

[0073] 10A , elongate member 102 includes a proximal region 200, a distal region 202, a proximal end 204, and a distal end 206. In some embodiments of the invention, elongate member 102 defines a lumen 208 that typically extends substantially between proximal region 200 and distal region 202.

[0074] Elongate member 102 is typically sized such that handle 110 remains outside the patient when distal end 206 is within the body, e.g., adjacent the target site. That is, proximal end 204 is located outside the body, and distal end 206 is located within the patient's heart. Accordingly, in some embodiments of the invention, the length of elongate member 102, i.e., the sum of the force transmission length and the distal portion length, is between about 30 cm and about 100 cm, depending on, for example, the particular application and / or target site.

[0075] The cross-sectional shape of the elongate member 102 can have any suitable configuration, and the invention is not limited in this respect. For example, the cross-sectional shape of the elongate member 102 can be substantially circular, oval, elliptical, or polygonal, among other possibilities. Furthermore, in some embodiments, the cross-sectional shape varies along the length of the elongate member 102. For example, in one embodiment, the cross-sectional shape of the proximal region 200 is substantially circular, while the cross-sectional shape of the distal region 202 is substantially oval.

[0076] In typical embodiments, the outer diameter of the elongate member 102 is sized to fit within a blood vessel of a patient's body. For example, in some embodiments, the outer diameter of the elongate member 102 is between about 0.40 mm and about 1.5 mm (i.e., between about 27 gauge and about 17 gauge). In some embodiments, the outer diameter of the elongate member 102 varies along the length of the elongate member 102. For example, in some embodiments, the outer diameter of the elongate member 102 tapers from the proximal end 204 to the distal end 206. In one particular embodiment, the outer diameter of the proximal region 200 of the elongate member 102 is about 1.5 mm. In this embodiment, approximately 4 cm from the distal end 206, the outer diameter begins to decrease such that the outer diameter at the distal end 206 of the elongate member 102 is about 0.7 mm. In further embodiments, the outer diameter of the elongate member 102 tapers from about 1.3 mm to about 0.8 mm at a distance of about 1.5 mm from the distal end 206. FIG. 10B is an example of a taper of the elongate member 102 that occurs smoothly over a length, for example, about 4 cm. FIG. 10C is an example of a taper that occurs more abruptly over a length, for example, about 1 mm or less. The taper can be applied to the elongate member 102 by a variety of methods. In some embodiments, the elongate member 102 is manufactured with a taper already built into it. In other embodiments, the elongate member 102 is manufactured without a taper, and the taper is formed by drawing the elongate member to the required outer diameter or by machining the distal region 202 so that the outer diameter tapers while the inner diameter remains constant.

[0077] In further embodiments, the elongate member 102 is fabricated from two pieces of material, each having a different diameter, joined together. For example, as shown in FIG. 10D , the elongate member 102 includes a main member 210 mechanically coupled to a handle (not shown in FIG. 10D ), the main member 210 having a length of about 50 cm to about 100 cm and an outer diameter of about 1.15 mm to about 1.35 mm. The main member 210 defines a main member lumen 214 extending substantially longitudinally therethrough, as shown in FIG. 2E . The main member is coaxially joined to an end member 212 having a length of about 2.5 cm to about 10 cm and an outer diameter of about 0.40 mm to about 0.80 mm. In some embodiments, the end member 212 is partially inserted into the main member lumen 214 on a substantially longitudinally opposite side of the handle 110. In some embodiments, the electrode 106 is positioned around the end member 212, for example, by being mechanically coupled thereto, while in other embodiments, the electrode 106 is integral with the end member 212. As seen in FIGS. 10D and 2E, where the end member 212 defines an end member lumen 216, the end member lumen 216 is in fluid communication with the main member lumen 214, as shown in FIG. 2E. The main member 210 and the end member 212 are joined in any suitable manner, such as, for example, by welding, soldering, a friction fit, or the use of adhesives, among other possibilities. Also, in some embodiments, the main member lumen 214 and the end member lumens 216 have substantially similar diameters, thereby reducing turbulence in the fluid flowing through the main member lumen 214 and the end member lumens 216.

[0078] In embodiments of the invention in which the elongate member 102 defines a lumen 208, the wall thickness of the elongate member 102 may vary depending on the application, and the invention is not limited in this regard. For example, if a more rigid device is desired, the wall thickness is typically greater than if more flexibility is desired. In some embodiments, the wall thickness of the force transfer region is about 0.05 mm to about 0.40 mm and remains constant along the length of the elongate member 102. In other embodiments in which the elongate member 102 is tapered, the wall thickness of the elongate member 102 varies along the elongate member 102. For example, in some embodiments, the wall thickness of the proximal region 200 is about 0.1 mm to about 0.4 mm, tapering to a thickness of about 0.05 mm to about 0.20 mm in the distal region 202. In some embodiments, the wall is tapered from inside to outside, thereby maintaining a consistent outer diameter and having a varying inner diameter. Alternative embodiments include walls that taper from the outside to the inside, thereby maintaining a consistent inner diameter and having a varying outer diameter. Further alternative embodiments include walls of the elongate member 102 that taper from both the inside and outside, for example, by reducing both diameters so that the wall thickness remains constant. For example, in some embodiments, the lumen 208 has a diameter of about 0.4 mm to about 0.8 mm in the proximal region 200 and tapers to a diameter of about 0.3 mm to about 0.5 mm in the distal region 202. In other alternative embodiments, the inner diameter increases while the outer diameter decreases, such that the wall tapers from both the inside and outside.

[0079] In some embodiments, the elongate member 102, and thus the medical device 100, is curved or bent, as shown in FIGS. 11A-11C. As used herein, the terms "curve" or "bend" refer to any region of non-linearity or any deviation from the longitudinal axis of the device, regardless of the angle or length of the bend or curve. The medical device 100 includes a substantially straight section 302 and a curved section 300 extending from the substantially straight section 302. Typically, the curved section 300 is located in the distal region 202 of the elongate member 102 and may occur at various angles over various lengths. In some examples, the curved section 300 has a relatively large radius, e.g., about 10 cm to about 25 cm, and spans a small portion of the circumference of a circle, e.g., about 20 to about 40 degrees, as shown in FIG. 11B. In an alternative embodiment, the curved section 300 has a relatively small radius, e.g., about 4 cm to about 7 cm, as shown in FIG. 11C, and spans a substantially larger portion of the circumference of a circle, e.g., about 50 to about 110 degrees, as shown in FIG. 11C. In one particular embodiment, the curved section 300 begins about 8.5 cm from the distal end 206 of the elongate member 102, has a radius of about 6 cm, and spans about 80 degrees of the circumference of the circle. In an alternative embodiment, the curved section has a radius of about 5.4 cm and spans about 50 degrees of the circumference of the circle. In a further embodiment, the curved section has a radius of about 5.7 cm and spans about 86 degrees of the circumference of the circle. This configuration facilitates positioning the elongate member 102 so that the distal end 206 is substantially perpendicular to the tissue through which a channel will be formed. This perpendicular positioning maximizes energy transfer when a user applies force through the elongate member 102, thereby providing enhanced feedback to the user.

[0080] The curved section 300 can be applied to the elongate strip 102 by various methods. For example, in one embodiment, the elongate strip 102 is manufactured in a curved mold. In another embodiment, the elongate strip 102 is manufactured in a substantially straight shape and then placed in a heated mold to cause the elongate strip 102 to assume a curved shape. Alternatively, the elongate strip 102 is manufactured in a substantially straight shape and forced to bend by grasping the elongate strip 102 just proximal to the region to be curved and applying a force to curve the distal region 202. In an alternative embodiment, the elongate strip 102 includes a main member 210 and an end member 212, as described with respect to FIG. 10D , which are joined together at an angle (not shown). That is, rather than being coaxial, the main member 210 and the end member 212 are joined at an angle, for example, 45°, relative to each other.

[0081] As described above herein, in some embodiments, the proximal region 200 of the elongate member 102 is structured to be coupled to an energy source. To facilitate this coupling, the proximal region 200 may include a hub 108 that allows the energy source to be electrically connected to the elongate member 102. Further details regarding the hub 108 are provided later herein. In other embodiments, the proximal region 200 is coupled to the energy source by other methods known to those skilled in the art, and the invention is not limited in this respect.

[0082] In an exemplary embodiment, the elongate member 102 is made from a conductive material that is biocompatible. As used herein, "biocompatible" refers to a material that is suitable for use within the body during a surgical procedure. Such materials include stainless steel, copper, titanium, and nickel-titanium alloys (e.g., NITINOL®), among others. Furthermore, in some embodiments, different regions of the elongate member 102 are made from different materials. In the example embodiment of FIG. 10D , the main member 210 is made from stainless steel to provide column strength to a portion of the elongate member 102 (e.g., the force-transmitting portion), and the end member 212 is made from a nickel-titanium alloy, such as NITINOL®, to provide flexibility to a portion of the elongate member 102 (e.g., the distal portion). Embodiments in which the force-transmitting portion of the elongate member 102 is fabricated from stainless steel often result in a medical device 100 having a similar amount of column strength to prior art devices, e.g., mechanical perforators such as Brockenbrough™ needles. This is beneficial in that it provides a familiar "feel" to users familiar with such devices. In some embodiments comprising a curved or bent elongate member 102, the straight section 302 is made from stainless steel to provide column strength to the elongate member 102, and the curved section 300 is made from a nickel-titanium alloy, such as NITINOL®, to provide flexibility to the elongate member 102. Additionally, using NITINOL® for the curved section 300 is advantageous because the superelastic properties of this material help to restore the shape of the curved section 300 after it has been straightened, for example, when the curved section 300 is placed in a dilator.

[0083] As described herein above, the electrical insulator 104 is disposed on at least a portion of the outer surface of the elongate member 102. In some embodiments, for example, as shown in FIG. 1 , the electrical insulator 104 covers the circumference of the elongate member 102 from the proximal region 200 of the elongate member 102 to the distal region 202 of the elongate member 102. In other words, the force transfer portion 114 and the distal portion 112 are electrically conductive, and the electrical insulator substantially covers the force transfer portion 114 and the distal portion 112, while the electrode 106 remains substantially uninsulated. When an energy source is coupled to the proximal region 200 of the elongate member 102, the electrical insulator 104 substantially prevents leakage of energy along the length of the elongate member 102, thus allowing energy to be delivered from the proximal region 200 of the elongate member 102 to the electrode 106.

[0084] In the embodiment shown in FIG. 1 , the electrical insulator 104 may extend to different locations on the distal region 202 ( FIG. 10 ), depending on the configuration of the electrode 106. Typically, the electrical insulator 104 extends to the proximal end 404 of the electrode 106, which may or may not coincide with the distal end of the elongate member 102. For example, as shown in FIG. 3A , the distal-most 1.5 mm of the elongate member 102 functions as at least a portion of the electrode 106. In these embodiments, the electrical insulator 104 extends to a point approximately 1.5 mm proximal to the distal end 206 of the elongate member 102. In the embodiment of FIGS. 3B-3C , an external component 400 coupled to the distal end of the elongate member 102 functions as the electrode 106. In such embodiments, the proximal end 404 of the electrode 106 substantially coincides with the distal end 206 of the elongate member 102, and thus the electrical insulator 104 extends to the distal end 206 of the elongate member 102. In some embodiments, the electrical insulator 104 extends beyond the distal end 206 of the elongate member 102 and covers a portion of the outer component 400. This typically helps secure the outer component 400 to the elongate member 102. The uncovered portion of the outer component 400 can then function as the electrode 106. In other embodiments, for example, as shown in FIG. 3A , the distal-most portion of the elongate member 102 as well as the rounded outer component 402 function as the electrode 106. In this embodiment, the electrical insulator 104 extends to a point substantially adjacent the distal end 206 of the elongate member 102. In one embodiment, electrical insulator 104 extends from distal end 206 of elongate member 102 to a point approximately 1.0 mm away.

[0085] The electrical insulator 104 can be one of many biocompatible dielectric materials, including, but not limited to, polytetrafluoroethylene (PTFE, Teflon®), parylene, polyimide, polyethylene terephthalate (PET), polyether block amide (PEBAX®), and polyether ether ketone (PEEK™), and combinations thereof. The thickness of the electrical insulator 104 may vary depending on the material used. Typically, the thickness of the electrical insulator 104 is about 0.02 mm to about 0.12 mm.

[0086] In some embodiments, the electrical insulator 104 comprises multiple dielectric materials. This is useful, for example, when different properties are required in different portions of the electrical insulator 104. In certain applications, for example, significant heat is generated at the electrode 106. In such applications, a material with a sufficiently high melting point is required for the distal-most portion of the electrical insulator 104 so that this portion of the electrical insulator 104 located adjacent the electrode 106 does not melt. Furthermore, in some embodiments, a material with a high dielectric strength is desirable for all or a portion of the electrical insulator 104. In some specific embodiments, the electrical insulator 104 has a combination of both of the aforementioned characteristics.

[0087] 2E , the electrical insulator 104 includes a first electrical insulating layer 218 made from a first electrical insulating material and a second electrical insulating layer 220 made from a second electrical insulating material and substantially thinner than the first electrical insulating layer 218. The first electrical insulating layer 218 substantially covers the main member 210 substantially adjacent the end member 212, the second electrical insulating layer 220 substantially covers the end member 212, and the electrode 106 is substantially separated from the second electrical insulating layer 220. In the illustrated embodiment, the first electrical insulating layer 218 overlaps the second electrical insulating layer 220 around the tapered region of the elongate member 102. This configuration provides desirable mechanical properties for the medical device 100 because thinner materials are typically less stiff than thicker materials. Additionally, in some embodiments of the present invention, the first electrical insulating layer 218 overlaps a portion of the second electrical insulating layer 220. However, in alternative embodiments of the present invention, electrical insulator 104 has any other suitable configuration, for example, having first electrical insulating layer 218 and second electrical insulating layer 220 made of the same material.

[0088] 3D , a heat shield 109 may be applied to the medical device 100 substantially adjacent the electrode 106 to, for example, prevent a distal portion of the electrical insulator 104 from melting due to heat generated by the electrode 106. For example, in some such embodiments, a thermal insulating material, such as zirconium oxide or polytetrafluoroethylene (PTFE), is applied over the distal-most approximately 2 cm of the electrical insulator 104. Typically, the heat shield 109 projects substantially radially outward from the remainder of the distal portion 112 and substantially longitudinally, in a direction from the electrode 106 toward the handle 110.

[0089] The electrical insulator 104 can be applied to the elongate strip 102 by a variety of methods. For example, if the electrical insulator 104 comprises PTFE, it may be provided in the form of heat shrink tubing that is placed over the elongate strip 102 and subjected to heat to substantially tighten around the elongate strip 102. For example, if the electrical insulating material is parylene, it may be applied to the elongate strip 102 by vapor deposition. In other embodiments, depending on the particular material used, the electrical insulator 104 may be applied to the elongate strip 102 using alternative methods, such as dip coating, co-extrusion, or spraying.

[0090] As described above, in an embodiment of the present invention, the elongate member 102 includes an electrode 106 at its distal region, which is configured to form a channel via radiofrequency perforation. As used herein, "radiofrequency perforation" refers to a procedure in which radiofrequency (RF) electrical energy is applied from a device to tissue to form a perforation or fenestration through the tissue. Without being limited to a particular theory of operation, it is believed that the RF energy acts to rapidly increase the tissue temperature to the point where water in the intracellular fluid is converted to vapor, inducing cell lysis as a result of the increased pressure within the cells. Furthermore, electrical breakdown can occur within the cells, where the electric field induced by the alternating current exceeds the dielectric strength of the medium located between the radiofrequency perforator and the cells, causing dielectric breakdown. Additionally, mechanical breakdown can occur, where the alternating current induces stress on polar molecules within the cells. When cell lysis and rupture occurs, a void is created, allowing the device to advance into the tissue with little resistance. The device from which energy is applied to achieve this effect, the electrode, increases the current density delivered to the tissue and is relatively small, approximately 15 mm 2 The electrode has an electrically exposed surface area of ​​approximately 15 mm. Additionally, the energy source is capable of applying high voltage through a high impedance load, as further described herein below. This is in contrast to RF ablation, which utilizes a larger tip device to deliver RF energy to a larger area in order to slowly dehydrate the tissue. In contrast to RF perforation, which creates a void in the tissue through which the device is advanced, the goal of RF ablation is to create a large, non-penetrating lesion in the tissue to disrupt electrical conduction. Thus, for purposes of the present invention, the electrode is conductive and exposed, with a surface area of ​​approximately 15 mm. 2 refers to a device having an exposed surface area of ​​0.1 mm or less and operable, when coupled to a suitable energy source and placed at a target site, to deliver energy to form perforations or fenestrations through tissue. Perforations are formed, for example, by vaporizing intracellular fluid of cells contacted by the electrodes such that voids, holes, or channels are formed in the tissue located at the target site.

[0091] In further embodiments, it may be desirable for the distal end 206 of the elongate member 102 to be closed, as shown in Figure 3A. For example, in some embodiments, as described later herein, it may be desirable for fluid to be injected radially from the elongate member 102 without being injected substantially distally from the elongate member 102, for example, through a side port in the elongate member 102. In these embodiments, the closed distal end 206 facilitates radial injection of fluid while preventing distal injection.

[0092] It is commonly believed that a distal opening is necessary to properly deliver contrast media to a target site. However, it has surprisingly been discovered that the medical device 100 can operate properly without a distal opening. Advantageously, these embodiments reduce the risk of tissue cores becoming lodged in such distal openings when forming a channel through tissue. Avoiding such tissue cores is desirable because they could enter the blood circulation, thereby creating the risk of blocking a blood vessel and resulting in a potentially fatal infarction.

[0093] 3A, a rounded outer component 402, e.g., an electrode tip, is operably coupled to the distal end 206. In this embodiment, the exposed portion of the distal region 202 (FIGS. 10A-10D), as well as the rounded outer component 402, function as the electrode 106. In such an embodiment, if the outer diameter of the elongate member 102 is 0.7 mm, the rounded outer component 402 is a hemisphere having a radius of approximately 0.35 mm, and the length of the distal-most exposed portion of the elongate member 102 is approximately 2.0 mm, the surface area of ​​the electrode 106 is therefore approximately 5.2 mm. 2 Alternatively, for example, as shown in Figure 2E, the distal end of end member 212 is closed and used as electrode 106 rather than as a separate external component.

[0094] In other embodiments, for example, as shown in Figures 3B and 3C, an electrically conductive, exposed outer component 400 is electrically coupled to the distal end of the elongate member 102 such that the outer component 400 acts as the electrode 106. In such embodiments, the outer component 400 is a cylinder having a diameter of about 0.4 mm to about 1 mm and a length of about 2 mm. Thus, the electrode 106 has a length of about 2.6 mm. 2 ~Approx. 7.1mm 2 has an exposed surface area of

[0095] The outer component 400 may take on various shapes, such as cylindrical, generally conical, or frusto-conical. The distal end of the outer component 400 may also have different configurations (e.g., rounded or flat). Additionally, some embodiments of the outer component 400 are made from a biocompatible, electrically conductive material, such as stainless steel. The outer component 400 can be coupled to the elongate member 102 by various methods. In one embodiment, the outer component 400 is welded to the elongate member 102. In another embodiment, the outer component 400 is soldered to the elongate member 102. In one such embodiment, the solder material itself comprises the outer component 400, for example, a quantity of solder is electrically coupled to the elongate member 102 to function as at least a portion of the electrode 106. In further embodiments, other methods of coupling the outer component 400 to the elongate member 102 are used, and the invention is not limited in this respect.

[0096] In these embodiments, as described herein above, the electrically exposed and conductive surface area of ​​the electrode 106 is approximately 15 mm 2 In embodiments where the electrical insulator 104 covers a portion of the outer component 400, the portion of the outer component 400 covered by the electrical insulator 104 is not included when determining the surface area of ​​the electrode 106.

[0097] Referring again to FIG. 3A , in some embodiments, distal portion 112 defines a distal tip 403, which is substantially atraumatic. In other words, the distal end of medical device 100 is configured to be substantially atraumatic or smooth. As used herein, the terms “atraumatic” and “smooth” refer to non-sharp structures, including rounded, blunt, or flat structures, among others, as shown, for example, in FIG. 3A . In embodiments in which the distal end of medical device 100 is substantially smooth, the smooth distal end is beneficial for avoiding undesired damage to non-target areas within the body. That is, if a mechanical force is unintentionally applied to medical device 100 when the distal end of medical device 100 is positioned in non-target tissue, medical device 100 is less likely to perforate the non-target tissue.

[0098] In some embodiments, the distal tip 403 is substantially bullet-shaped, as shown in FIG. 2E , which allows an intended user to pull the distal tip 403 across the surface of tissue within a patient's body to capture tissue at a target site. For example, if the target site includes the fossa ovalis, the bullet-shaped tip can capture the fossa ovalis such that a longitudinal force applied to a proximal portion of the medical device 100 advances the electrode 106 into and through the fossa ovalis rather than sliding it out of the fossa ovalis, as described further herein below. Because of the tactile feedback provided by the medical device 100, this action facilitates positioning of the medical device 100 prior to energy delivery to form a channel.

[0099] As described herein above, in some embodiments, the medical device 100 includes a hub 108 coupled to a proximal region. In some embodiments, the hub 108 is part of the handle 110 of the medical device 100 and facilitates connection of the elongate member 102 to an energy source and a fluid source, such as a contrast fluid source.

[0100] 12A and 12B , the proximal region 200 of the elongate member 102 is electrically coupled to a hub 108, which is configured to electrically couple the elongate member 102 to an energy source, such as a radio frequency generator. In one embodiment, the hub 108 includes an electrically conductive wire 500 connected at one end to the elongate member 102, for example, by welding or brazing. The other end of the wire 500 is coupled to a connector (i.e., connector means for receiving), such as a banana jack 502, which is electrically coupleable to a banana plug 504, which is electrically coupled to an energy source. Thus, electrical energy can be delivered from the energy source through the plug 504, the jack 502, and the wire 500 to the elongate member 102 and the electrode 106. In other embodiments, other hubs or connectors that allow the elongate member 102 to be connected to a fluid source and an energy source are used, and the invention is not limited in this respect.

[0101] In some embodiments, medical device 100 is a transseptal puncture device that includes an electrically conductive elongate member, an electrical connector in electrical communication with the elongate member, and an electrode at the distal end of the electrically conductive elongate member for delivering energy to tissue. A method of using the transseptal puncture device includes (1) connecting an electrically conductive component in electrical communication with an energy source to the electrical connector, and (2) delivering electrical energy to tissue through the electrode. The electrically conductive component can include a plug, such as plug 504, and a wire connected thereto. Some embodiments of the method further include (3) disconnecting the electrically conductive component from the electrical connector. In such embodiments, the electrically conductive component is releasably connected.

[0102] In some embodiments, the hub 108 is structured to be operably coupled to a fluid connector 506, e.g., a luer lock, connected to the tubing 508. The tubing 508 is structured to be operably coupled at one end to a suction device, a fluid source 712 (e.g., a syringe), or a pressure sensing device (e.g., a pressure transducer 708). The other end of the tubing 508 is operably couplable to the fluid connector 506 such that the tubing 508 and the lumen 208 are in fluid communication with each other, thus enabling fluid flow between an external device and the lumen 208. In embodiments in which the hub 108 is part of the handle 110, fluid and / or electrical connections need not be made solely with the hub 108; i.e., connections may be made to other portions of the handle 110 or to portions of the medical device 100 other than the handle.

[0103] In some embodiments, the hub 108 further comprises one or more curvature direction or orientation indicators 510 located on one side of the hub 108 to indicate the direction of the curved section 300. The orientation indicator(s) 510 may include ink, etching, or other materials that enhance visualization or tactile feel.

[0104] In some embodiments of the invention, handle 110 includes a relatively large grippable surface so that tactile feedback can be transmitted relatively efficiently, for example, by transmitting vibrations. In some embodiments of the invention, handle 110 includes ridges 512, for example, on hub 108, that enhance this tactile feedback. Ridges 512 allow an intended user to fully grip handle 110 without tightly holding handle 110, thereby facilitating the transmission of this feedback.

[0105] In some embodiments of the invention, medical device 100 defines a lumen circumferential surface 602 that extends substantially circumferentially relative to end member lumen 216, as shown in Figure 2E, and lumen circumferential surface 602 is substantially covered with lumen electrical insulating material 604. This configuration prevents or reduces electrical loss from lumen circumferential surface 602 to any electrically conductive fluid located within lumen 208. However, in other embodiments of the invention, lumen circumferential surface 602 is not substantially covered with lumen electrical insulating material 604.

[0106] Also, in some embodiments of the invention including a curved section 300, the curved section 300 defines a center of curvature (not shown), and the side port(s) 600 extend from the lumen 208 substantially toward the center of curvature. This configuration substantially prevents the edges of the side port(s) 600 from catching tissue as the tissue is pierced. However, in alternative embodiments of the invention, the side port(s) 600 extend in any other suitable orientation.

[0107] In some embodiments, one or more radiopaque markers 714 (as shown in FIG. 8 ) are associated with the medical device 100 to highlight the location of important landmarks on the medical device 100. Such landmarks include the location where the elongate member 102 begins to taper, the location of the electrode 106, or the location of any side port(s) 600. In some embodiments, the entire distal region 202 of the medical device 100 is radiopaque. This can be achieved by filling the electrical insulator 104, such as Pebax®, with a radiopaque filler, such as bismuth.

[0108] In some embodiments, the shape of medical device 100 may be modifiable. For example, in some applications, it may be desirable for medical device 100 to be able to change between a straight configuration, such as that shown in FIG. 1, and a curved configuration, such as that shown in FIGS. 11A-11C. This may be achieved by coupling a pull wire to medical device 100 such that the distal end of the pull wire is operably coupled to a distal region of medical device 100. When a user applies force to the proximal end of the pull wire, either directly or via an actuation mechanism, distal region 202 of medical device 100 is deflected in a particular direction. In other embodiments, other means for modifying the shape of medical device 100 are used, and the invention is not limited in this respect.

[0109] In some embodiments, the medical device 100 includes at least one additional conductive component located proximal to the electrode 106. For example, the conductive component may be a metal ring disposed on or around the electrical insulator 104 having a sufficiently large surface area so that it can operate as a return electrode. In such embodiments, the medical device 100 may function in a bipolar manner, whereby electrical energy flows from the electrode 106, through tissue at the target site, and to the at least one additional conductive component. Furthermore, in such embodiments, the medical device 100 includes at least one electrical conductor, e.g., a wire, for conducting electrical energy from the at least one additional conductive component to a current sink, e.g., circuit ground.

[0110] In some embodiments, the medical device 100 is used in conjunction with a suitable radio frequency energy source to perforate material within a patient's body. The energy source may be a radio frequency (RF) electrical generator 700 operable in the range of about 100 kHz to about 1000 kHz and designed to generate high voltage for a short period of time. More specifically, in some embodiments, the voltage generated by the generator increases from about 0 V (peak-to-peak) to greater than about 75 V (peak-to-peak) in less than about 0.6 seconds. The maximum voltage generated by the generator 700 may be about 180 V peak-to-peak to about 3000 V peak-to-peak. The waveform generated may vary and may include, for example, a sine wave, a square wave, or a pulsed square wave, among others. During delivery of the radio frequency energy, the impedance load may increase due to the occurrence of tissue damage near the target site or the formation of a vapor layer after cell rupture. In some embodiments, the generator 700 is operable to continue increasing the voltage even as the impedance load increases. For example, energy may be delivered to tissue within the body at a voltage that rapidly increases from about 0 V (RMS) to about 220 V (RMS) over a period of about 0.5 seconds to about 5 seconds.

[0111] Without being limited to a particular theory of operation, it is believed that under certain circumstances, as described above, delivery of radio frequency energy can cause dielectric breakdown and arcing, which separates polar molecules. The combination of these factors can lead to the formation of an insulating vapor layer around the electrode, causing an increase in impedance around the electrode, which can increase to, for example, over 4000 Ω. In some embodiments, the voltage continues to increase despite this high impedance. Further increasing the voltage can be desirable because it increases the intensity of the radiofrequency therapy, which allows for increased perforation speed. An example of a generator suitable for this application is the BMC RF Perforation Generator (Model No. RFP-100, Baylis Medical Company, Montreal, Canada). This generator delivers continuous RF energy at approximately 460 kHz.

[0112] In some embodiments, a dispersive electrode or grounding pad 702 is electrically coupled to the generator 700 for contacting or attaching to the patient's body to provide a return path for the RF energy when the generator 700 is operated in a monopolar mode. Alternatively, in embodiments utilizing a bipolar device, a grounding pad is not required as the return path for the RF energy is provided by additional conductive components, as described above.

[0113] 12A and 12B, the medical device 100 is operably coupled to the tubing 508 using a fluid connector 506 located at the proximal end of the medical device 100. In some embodiments, the tubing 508 is made from a polymeric material, such as polyvinyl chloride (PVC) or another flexible polymer. Some embodiments include the tubing 508 operably coupled to an adapter 704. The adapter is constructed to provide a flexible area for a user to handle when releasably coupling an external pressure transducer, fluid source, or other device to the adapter. In some embodiments, the bonds between the elongate member 102, the fluid connector 506, and the tubing 508, and between the tubing 508 and the adapter 704, are temporary bonds, such as luer locks or other releasable components. In alternative embodiments, the bonds are substantially permanent, for example, a bonding agent, such as a UV-curable adhesive, epoxy, or another type of bonding agent. Some embodiments of the medical device 100 include a distal aperture in fluid communication with the lumen 208, the distal aperture being a side port 600, although some alternative embodiments have a distal aperture defined by an open distal end.

[0114] In one broad aspect, the electrosurgical medical device 100 can be used to deliver energy to a target site within a patient's body to puncture or form voids or channels in the material at the target site. Further details regarding the delivery of energy to target sites within the body can be found in U.S. patent application Ser. Nos. 13 / 113,326 (filed May 23, 2011), 10 / 347,366 (filed January 21, 2003, now U.S. Patent No. 7,112,197), 10 / 760,749 (filed January 21, 2004), 10 / 666,288 (filed September 19, 2003), and 11 / 265,304 (filed November 3, 2005), as well as U.S. Patent Nos. 7,048,733 (filed September 19, 2003) and 6,565,562 (issued May 20, 2003), all of which are incorporated herein by reference.

[0115] In one particular embodiment, the target site comprises tissue within the patient's heart, for example, the atrial septum of the heart. In such an embodiment, the target site may be accessed via the inferior vena cava (IVC), for example, via the femoral vein.

[0116] In one such embodiment, the intended user introduces a guidewire into the femoral vein, typically the right femoral artery, and advances it toward the heart. A guide sheath, such as that described in U.S. patent application Ser. No. 10 / 666,288 (filed Sep. 19, 2003), previously incorporated by reference, is then introduced over the guidewire into the femoral vein and advanced toward the heart. The distal end of the guidewire and sheath are then positioned within the superior vena cava. These steps may be performed using fluoroscopic imaging. With the sheath in place, a dilator, such as the TorFlex™ Transseptal Dilator from Baylis Medical Company Inc. (Montreal, Canada) or a dilator such as that described in U.S. patent application Ser. No. 11 / 727,382 (filed Mar. 26, 2007), previously incorporated by reference, is introduced into the sheath and over the guidewire and advanced through the sheath into the superior vena cava. The sheath, for example, in embodiments including a substantially rigid dilator, helps prevent the dilator from damaging or puncturing the vessel wall. Alternatively, the dilator may be fully inserted into the sheath before entering the body, and both may be advanced simultaneously toward the heart. Once the guidewire, sheath, and dilator are positioned within the superior vena cava, the guidewire is removed from the body, and the sheath and dilator are slightly retracted to enter the right atrium of the heart. An electrosurgical device, such as the medical device 100 described herein above, is then introduced into the lumen of the dilator and advanced toward the heart.

[0117] In this embodiment, after inserting the electrosurgical device into the dilator, the user positions the distal end of the dilator against the atrial septum. The electrosurgical device is then positioned so that the electrode 106 is aligned with or slightly protrudes beyond the distal end of the dilator. Once the electrosurgical device and dilator are properly positioned, for example, against the fossa ovalis of the atrial septum, various additional steps can be performed. These steps may include measuring one or more characteristics of the target site, such as an electrogram or ECG (electrocardiogram) tracing and / or pressure measurements, or delivering a substance to the target site, such as delivering contrast media through the side port(s) 600 and / or the open distal end 206. Such steps can facilitate localized placement of the electrode 106 at the desired target site. Additionally, as described herein above, tactile feedback provided by the proposed medical device 100 can be used to facilitate placement of the electrode 106 at the desired target site.

[0118] With the electrosurgical device and dilator positioned at the target site, energy is delivered from an energy source through the medical device 100 to the target site. For example, energy is delivered through the elongate member 102 to the electrode 106 and into the tissue at the target site. In some embodiments, the energy is delivered at a voltage of at least about 75 V (peak-to-peak) and a power of at least about 5 W, which functions to vaporize cells in the vicinity of the electrode, as described above, thereby forming a void or perforation through the tissue at the target site. As described above, when approaching the heart via the inferior vena cava, the user applies a force in a substantially cranial direction to the handle 110 of the electrosurgical device while energy is being delivered. The force is then transmitted from the handle to the distal portion 112 of the medical device 100 such that the distal portion 112 advances at least partially through the perforation. In these embodiments, energy delivery is stopped when the distal portion 112 passes through the target tissue, i.e., when it reaches the left atrium. In some embodiments, the step of delivering energy occurs for a period of about 1 second to about 5 seconds.

[0119] At this point in the procedure, the diameter of the perforation is typically substantially similar to the outer diameter of the distal portion 112. In some embodiments, a user may desire to enlarge the perforation so that another device, such as an ablation catheter or other surgical device, can pass through the perforation. Typically, to do this, the user applies force to the proximal region of the dilator, for example, in a cranial direction if the heart was approached via the inferior vena cava. This force typically causes the distal end of the dilator to enter the perforation and pass through the atrial septum. The electrosurgical device is operable to assist in guiding the dilator through the perforation by acting as a substantially rigid rail for the dilator. In such embodiments, the curvature, e.g., the curved section 300 of the medical device 100, typically assists in anchoring the electrosurgical device within the left atrium. In typical embodiments, as force is applied, a larger diameter portion of the dilator passes through the perforation, thereby dilating, expanding, or enlarging the perforation. In some embodiments, the user also applies torque to assist in manipulating the dilator. Alternatively, in embodiments in which the device is tapered, the device may be advanced further into the left atrium so that a larger portion of the device enters and dilates the perforation.

[0120] In some embodiments, when the perforation is dilated to a suitable size, the user stops advancing the dilator. A guide sheath is then advanced over the dilator through the perforation. In alternative embodiments, the sheath is advanced simultaneously with the dilator. At this point in the procedure, the user can retract the dilator and electrosurgical device proximally through the sheath, leaving only the sheath in place within the heart. The user can then perform a surgical procedure on the left side of the heart through the sheath, for example, introducing a surgical device through the sheath into the femoral vein to perform a surgical procedure to treat an electrical or morphological abnormality within the left side of the heart.

[0121] When the inventive device as described herein above is used to perform the procedures described herein, the user can maintain the "feel" of a mechanical perforator, e.g., a Brockenbrough™ needle, without the need for a sharp tip and a large amount of mechanical force to perforate the atrial septum. Rather, a radiofrequency perforator, e.g., electrode 106, as described herein above, is used to create a gap or channel through the atrial septum, while reducing the risk of accidental puncture of non-target tissue.

[0122] In other embodiments, the methods of the present invention can be used for therapeutic procedures involving other regions within the body, and the present invention is not limited in this respect. For example, embodiments of the devices, systems, and methods of the present invention can be used to treat pulmonary atresia rather than the atrial septum. In some such embodiments, a sheath is introduced into the patient's vasculature and guided to the heart, as described above. A dilator is then introduced within the sheath and advanced toward the heart, where it is positioned against the pulmonary valve. An electrosurgical device comprising an electrode is then introduced into the proximal region of the dilator and advanced so that it is also positioned against the pulmonary valve. Energy is then delivered from an energy source through the electrode of the electrosurgical device to the pulmonary valve, resulting in the formation of a puncture or void, as described above. As the electrosurgical device passes through the valve, a user can apply force to the proximal region of the dilator, for example, in a substantially cranial direction. Force can be transmitted to the distal region of the dilator so that it enters the puncture and advances through the pulmonary valve. As the larger diameter region of the dilator passes through the puncture, the puncture or channel is enlarged.

[0123] In other applications, embodiments of the device of the present invention can be used to form voids or channels in or through other tissues of the body, such as in or through the myocardium of the heart. In other embodiments, the device is used to form channels through completely or partially blocked lumens in the body. Examples of such lumens include, but are not limited to, blood vessels, bile ducts, respiratory airways, and vessels and / or ducts of the digestive, urinary, and / or reproductive systems. In such embodiments, the device is typically positioned so that the device's electrodes are substantially adjacent to the material to be punctured. Energy is then delivered from the energy source through the electrodes 106 to the target site, resulting in the formation of a void, puncture, or channel in or through the tissue.

[0124] The present disclosure describes embodiments of kits and their components that together form a device in which fluid communication between the lumen of a medical device and the surrounding environment is provided by a conduit cooperatively defined by the medical device and a tubular member into which the device is inserted. The medical device and tubular member are configured to fit together such that the outer surface of a distal region of the medical device cooperates with the inner surface of the tubular member to define a conduit between a side port of the medical device and the distal end of the tubular member. The conduit is operable for various uses, including injecting fluids, withdrawing fluids, and measuring pressure. Methods of assembling and using the device are also described.

[0125] The present disclosure further describes an electrosurgical device configured for the transmission of force from a distal portion of the electrosurgical device to a proximal portion of the electrosurgical device, thereby providing tactile feedback to a user. The proximal portion of the device includes a handle and / or hub, and the handle (or hub) includes an electrical connector (i.e., connector means) configured to releasably receive an electrically conductive component operable for electrical communication with an energy source to enable a user to puncture a tissue layer. In some cases, a radio frequency (RF) energy source is used to selectively apply RF energy to tissue. Exemplary embodiments of the device include insulation to protect the user and the patient.

[0126] Another aspect of the present invention includes a puncture device and method for accessing the left atrium (or pericardial cavity) of the heart, which method includes creating a channel substantially through the interatrial septum (or parietal pericardium) and delivering energy to the interatrial septum (or parietal pericardium) in a manner that prevents inadvertent damage to surrounding tissue due to automatic shutoff of energy after the channel is created. While the disclosed device is suitable for accessing both the left atrium and the pericardial cavity, for the sake of brevity, the following description focuses on gaining access to the left atrium of the heart by delivery of energy to the interatrial septum. The concepts disclosed below regarding automatic shutoff of energy after a channel is created are applicable to both epicardial and transseptal procedures.

[0127] The disclosed devices, systems, and methods can be used in other procedures. For example, the disclosed systems and methods can be used in a TIPS procedure, where the tissue to be punctured is liver tissue between the liver's inflowing portal vein and outflowing hepatic vein, the anatomical space the device enters after puncture is the inflowing portal vein, and the substance (fluid or tissue) the device enters after puncture is blood. An electric current is sent through the bloodstream for the purpose of determining impedance or dielectric to control the cessation of energy delivery.

[0128] Other examples in which the disclosed devices and systems can be used include the following, where the delivery of radiofrequency energy is automatically stopped after the puncture device has completed puncturing the target tissue and entered the desired anatomical space. The automatic cessation of energy delivery is controlled by a sensor that determines the value of a parameter for the current flowing through the material in the target anatomical space, which in the example of this paragraph is blood. In a Potts Shunt procedure, the tissue to be punctured is the tissue between the left pulmonary artery and the descending aorta, the anatomical space the device enters after puncture is the descending aorta, and the material (fluid or tissue) the device enters after puncture is blood. In the case of a procedure involving accessing a blood vessel, the tissue to be punctured is the blood vessel wall, the anatomical space the device enters after puncture is the blood vessel (or target blood vessel), and the material (fluid or tissue) the device enters after puncture is blood. In a typical procedure for creating a shunt, the tissue to be punctured is a substance between two parts (or anatomical structures) of the body, the anatomical space into which the device enters after puncture is the target anatomical structure, and the substance (fluid or tissue) into which the device enters after puncture is a substance contained inside the target anatomical structure. In a procedure for transcaval access in TAVR, the tissue to be punctured is a tissue between the abdominal aorta and the adjacent inferior vena cava (IVC), the anatomical space into which the device enters after puncture is the abdominal aorta, and the substance (fluid or tissue) into which the device enters after puncture is blood. In the above procedure, an electric current is sent through the substance (fluid or tissue) into which the device enters after puncture for the purpose of determining impedance or dielectric, thereby stopping the delivery of energy for the puncture.

[0129] An example of a device suitable for use with an embodiment of a method for puncturing a patient's atrial septum can be seen in FIG. 13a. The puncture device 900 comprises an elongate member having a distal region 910 terminating in a distal tip 912. The distal tip 912 comprises an energy delivery device 914, such as an electrode, configured to deliver energy into tissue. Additionally, the puncture device 900 typically has an additional electrode 916 on the distal tip 912 that can be used to detect whether the target tissue has been punctured. The elongate member further comprises a proximal portion 920 having a hub 922 attached thereto. The hub 922 connects to a generator for providing energy to the puncture device 900. The puncture device 900 can be a hollow conductive tube, such as a hypotube (FIG. 13b), or a wire, such as a guidewire (FIG. 13c).

[0130] 13b, the elongate member comprises a hollow conductive tube 930 forming a lumen 932 extending from the proximal end of the device to the distal portion 910. The conductive tube can be formed from any conductive material capable of delivering energy from the generator to the distal tip 912, such as stainless steel. The puncture device comprises a side port 936 that is in fluid communication with the lumen 932 and can be used to inject or aspirate fluids during the procedure. The conductive tube 930 is coated with an insulating layer 934, e.g., PTFE (polytetrafluoroethylene), by which energy is delivered to an energy delivery device 914 at the distal tip 912. In an exemplary embodiment, an electrode 916 located at the distal tip 912 is used to send an electrical current to the tissue being punctured. A sensor, which may be a component of the puncture device 900 or of the generator, can detect a change in the characteristics of the current returning from the tissue and signal the generator that the puncture is complete, which then shuts off the delivery of energy. For example, the sensor may be able to detect changes in impedance or dielectric properties of a material in contact with an electrode 916 at the distal tip 912. To enable this, the electrode 916 is electrically isolated from the energy delivery device 914. This can be achieved by covering a portion of the energy delivery device 914 with an electrically insulating material 917, such as by surrounding the electrode 916 with insulating material 917, thereby electrically isolating the electrode 916. A wire 918 connects the electrode 916 to the generator and typically extends along the length of the lancing device 900. In some embodiments (e.g., FIG. 13b), this wire 918 is between the insulator 934 and the conductive tube 930, which typically requires that the wire 918 be insulated from the conductive tube 930. In an alternative embodiment, the wire 918 extends along the exterior of the insulator 934.

[0131] In an alternative embodiment of the invention, the puncture device 900 is comprised of a wire configured to deliver energy into tissue ( FIG. 13 c). In the illustrated example, the puncture device 900 is formed from a core wire 940. In the embodiment of FIG. 13 c, the core wire 940 includes a distal taper 942, and a coil 944 surrounds the distal taper 942 and terminates at a distal tip 912. The components of the puncture device 900 can be varied, including at least the diameter of the core wire 940, the length of the distal taper 942, or the coil 944. For example, the diameter of the core wire 940 (in addition to the material from which it is constructed) helps determine the flexibility of the wire. A relatively smaller diameter provides increased flexibility. The distal taper 942 affects torque transmission capabilities. A steeper taper over a shorter distance results in a tendency for the distal portion 910 to protrude (i.e., fold back on itself), while a gradual taper over a longer distance provides greater torque. This affects the ability of the puncture device 900 to maneuver around bends in the vasculature. The coil extending from the distal taper 942 to the distal tip 912 helps to maintain the shape of the distal tip 912, affects trackability, and can provide tactile feedback to the user. For example, a relatively stiff coil can provide more tactile feedback to the user, but can make it more difficult for the puncture device 900 to navigate through tortuous blood vessels. In some embodiments, the core wire 940 and coil 944 are made of a conductive material, such as nitinol or stainless steel, coated with an insulating material 934 to ensure that delivery of energy to tissue occurs from the energy delivery device 914 at the distal tip 912. The insulating material 934 can be any suitable electrically insulating material, such as PTFE (polytetrafluoroethylene). The distal tip 912 comprises the energy delivery device 914 and an electrode 916 that is electrically isolated from the energy delivery device 914. This isolation can be achieved by covering a portion of the distal tip 912 with an insulating material 917 to separate contact between the electrode 916 and the energy delivery device 914. In some embodiments, the electrode 916 is connected to a sensor capable of detecting changes in the electrical current traveling from one electrode through the tissue and back through the other electrode.The sensor can be a component of the lancing device 900 or a component of the generator. For example, the sensor can detect a change in the impedance or dielectric properties of a material in contact with an electrode 916 at the distal tip 912. A wire 918 connects the electrode 916 to the generator and may run along the length of the lancing device 900. In some embodiments, this wire 918 is inside the insulator 934 along with the core wire 940, which requires that the wire 918 be insulated from the core wire 940. In an alternative embodiment, the wire 918 runs along the exterior of the insulator 934.

[0132] In a typical embodiment, the placement of the electrodes 916 is on the face of the distal tip 912. Some examples of electrode 916 placement are shown in FIGS. 14a-14c. The electrodes 916 may be spaced apart at varying distances while still remaining functional. The electrodes 916 should be sufficiently spaced apart to allow current to flow from one electrode through the tissue to the other. As previously mentioned, the electrodes 916 should be electrically isolated from the energy delivery device 914 so as not to interfere with the delivery of energy. In the embodiment of FIG. 14a, the electrodes 916 are positioned on the periphery of the face, and the energy delivery device 914 is in the center of the distal face to provide the puncture. In the embodiment of FIG. 14b, the electrodes 916 are positioned on the centerline of the energy delivery device 914. In some embodiments, the insulating material 917 is positioned to form a flap in the tissue during puncture (e.g., FIG. 14c).

[0133] An alternative embodiment of the device is shown in FIG. 15 a, in which the electrodes 916 are positioned on the sides of the distal tip 912. In some such embodiments, the electrodes 916 are laterally opposite one another. In use, the electrodes 916 are in contact with the target tissue while the physician applies pressure to the tissue 1110, causing it to tent over the distal tip 912, as seen in FIG. 15 b. As with the previous embodiment, the electrodes 916 are electrically isolated from the energy delivery device 914 at the distal tip 912. For example, in some embodiments, the electrodes 916 are attached to an insulator 934 that covers the distal region 910 of the lancing device 900. Alternatively, there may be a separate band of insulating material 917 positioned on the edge of the distal tip 912 to which the electrodes 916 are attached.

[0134] 16 , in some embodiments, the electrodes 916 located at the distal tip 912 of the lancing device 900 are connected to a generator via wires from a hub 922. The wires are used to deliver energy to the energy delivery device 914 and to deliver current to the electrodes 916. For example, the generator 1210 delivers high frequency energy, such as radio frequency energy, in pulses to the target tissue via the energy delivery device 914, while between pulses the generator 1210 provides a current of known voltage to the lancing device 900, which sends the current to one of the electrodes 916 at the distal tip 912. The current then flows from one electrode 916 through the tissue 1220 (the tissue 1220 is represented in the drawings by a resistor symbol) and back through the other electrode 916. The impedance is then detected by the sensor 1230 and this information is used by the generator switch 1240 to cut off the delivery of energy via the energy delivery device 914 once the tissue is punctured and the impedance decreases.

[0135] In one embodiment, the generator has a hardware switch that responds to a change in impedance and stops delivering energy to the energy delivery device 914. An example of such a switch is a comparator connected to a gate switch, such as a MOSFET.

[0136] In another embodiment, a software algorithm for shutting off energy delivery for a puncture is implemented within the generator, as shown in the example of FIGS. 17A and 17B. Referring now to the algorithm of FIG. 17A, step 1300 is to send a current having a known voltage to the tissue. Step 1310 is to detect the impedance of the tissue or fluid in contact with the distal tip 912 of the puncture device and determine whether the value is a tissue or blood value. If the impedance value is a tissue impedance value (1320), the algorithm branches to step 1322, which continues to deliver energy, and step 1322 branches back to step 1300. If the value determined in step 1310 is a blood impedance value (1330), the algorithm branches to step 1332, which stops energy delivery through the energy delivery device 914. An alternative embodiment with an impedance threshold is shown in FIG. 17B. As seen on the right of FIG. 17B, the threshold is below the tissue impedance value and above the blood impedance value. In this embodiment, step 1300 is to send a current having a known voltage to the tissue. Step 1310 is to determine the value of the impedance of the tissue and / or fluid in contact with the distal tip 912 of the lancing device. In step 1340, the detected value of the impedance is compared to a threshold. If the detected impedance is greater than or equal to the threshold (yes), the detected impedance is closer to the impedance value of the tissue, and the algorithm branches to step 1342 to continue delivery. If the detected impedance is less than the threshold (no), the detected impedance is closer to the impedance value of the blood, and the algorithm branches to step 1344 to stop delivering energy through the energy delivery device 914.

[0137] The above description of the algorithm of Figures 17A and 17B discloses detecting fluid, specifically blood, impedance, which is suitable for procedures requiring access to the left atrium. Alternative embodiments of the algorithm of Figures 17A and 17B suitable for accessing the pericardial space include detecting pericardial fluid and / or blood impedance. Similarly, the following description of the algorithm of Figures 19A and 19B discloses detecting blood impedance. Alternative embodiments of the algorithm of Figures 19A and 19B suitable for accessing the pericardial space include detecting pericardial fluid and / or blood impedance.

[0138] 18 illustrates an alternative embodiment in which a sensor 1430 detects the dielectric properties of a material in contact with an electrode 916 located at the distal tip 912 of the lancing device 900. Similar to that described above, a current of known voltage is delivered to one of the electrodes 916 at the distal tip 912 while the generator 1410 delivers a pulse of energy for lancing via the energy delivery device 914. The current flows from one electrode 916 through the tissue 1220 and returns through the other electrode 916. Tissue and blood each have different dielectric properties, whereby a change in the dielectric properties is determined by the sensor 1430 to indicate whether the tip is in tissue or in a fluid (e.g., blood or pericardial fluid). The dielectric properties of the material in contact with the distal tip 912 are then used by a generator switch 1440 to control whether the generator 1410 continues to deliver energy or cuts off delivery of energy via the energy delivery device 914.

[0139] In some embodiments that use dielectric properties, a hardware configuration for controlling energy delivery may be employed. In some such examples, the generator has a hardware switch that responds to changes in dielectric properties at the distal tip. In some examples, the comparator is connected to a gate switch that can be opened when the dielectric properties of blood flow or pericardial fluid (i.e., not the tissue being punctured) are detected, thereby stopping the delivery of energy to the energy delivery device 914.

[0140] An alternative embodiment using dielectric properties to control the delivery of energy through the energy delivery device 914 is implemented in a software algorithm, and an example is shown in FIGS. 19A and 19B. In the algorithm of FIG. 19A, step 1500 is for sending a current of known voltage. In step 1510, the dielectric property of the tissue or fluid in contact with the distal tip 912 of the lancing device is determined and checked to see if the value is that of tissue 1520 or that of blood 1530. If the dielectric value is that of tissue 1520, the algorithm branches to step 1522, which continues the delivery of energy. Step 1522 branches back to step 1500. If the dielectric value is that of blood 1530, the algorithm branches to step 1532, which stops the delivery of energy to the energy delivery device 914. An alternative implementation using a dielectric threshold is shown in FIG. 19B. In this embodiment, step 1500 is for sending a current of known voltage, and the dielectric properties of the material in contact with the distal tip 912 are determined in step 1510. The detected dielectric properties are compared to a threshold in step 1540. Any detected dielectric value above the threshold indicates that the material in contact with the distal tip of the lancing device is tissue, and therefore energy delivery to the energy delivery device 914 continues (step 1542). Step 1542 branches back to step 1500. When the detected dielectric value falls below the threshold, energy delivery to the energy delivery device 914 is stopped (step 1544).

[0141] 13-20 and described above, the sensor can be a component of the lancing device 900 or a component of the generator. In some embodiments in which the lancing device includes sensor 1230 (FIG. 16) or sensor 1430 (FIG. 18), the sensor is capable of detecting a value of current associated with current flowing between two electrodes 916 and through a material in contact with distal tip 912, and the lancing device has means for communicating the value of the current between the two electrodes to generator switch 1240 (FIG. 16) or switch 1440 (FIG. 18). In some embodiments in which generator 1210 (FIG. 16) or generator 1410 (FIG. 18) includes a sensor, the lancing device includes means for communicating to the sensor a first electrode current parameter from electrode 916 delivering current of known voltage and a second electrode current parameter from electrode 916 through which the current returns to lancing device 900.

[0142] A method of using the aforementioned puncture device includes the steps of delivering energy to the atrial septum of a patient's heart through an energy delivery device, advancing the energy delivery device through the atrial septum, and automatically ceasing the delivery of energy upon completion of the puncture.

[0143] A number of steps may occur prior to delivering energy to the septum: for example, various therapeutic compositions or medications, such as antibiotics or anesthetics, may be administered to the patient, and various diagnostic tests, including imaging, may be performed.

[0144] FIG. 20 illustrates an exemplary embodiment of a system 1600 that can be used during a transseptal puncture to gain access to a patient's left atrium. The system 1600 includes a puncture device 900 having a distal portion 910 with an energy delivery device 914 at its distal tip 912, a dilator 1620, and a sheath 1630. A generator 1640 is used to deliver energy to the energy delivery device 914 through a connecting wire 1650 attached to a hub 922 located at the proximal end 920 of the puncture device 900. The energy delivered to the energy delivery device 914 can be in the high frequency range, e.g., radio frequency energy. The distal tip 912 of the puncture device 900 includes electrodes 916 ( FIGS. 13 b and 13 c ) located at the distal tip 912. An electric current can be sent between the electrodes 916. A quantifiable value of the electric current can be detected as the electric current travels through material while flowing between the electrodes 916 at the distal tip 912. For example, the impedance or dielectric properties of blood (or alternatively, pericardial fluid) and septal tissue are different. The sensor determines a change in current when the distal tip 912 is no longer in contact with tissue after completing the puncture and is now in contact with blood in the left atrium, and a signal is sent back to the generator 1640 to stop delivering energy to the energy delivery device 914.

[0145] Depending on the ease of access of the vascular system, various approaches to the insertion of the electrosurgical device can be used. For example, one application of the method of the present invention uses the embodiment of the electrosurgical device outlined in Figure 13b. The embodiment of Figure 13b comprises a hollow conductive tube, such as a hypotube, typically having the properties of a needle. In this embodiment of the method, the puncture device 900 passes through the inferior vena cava and enters the right atrium. The steps of this embodiment of the method include:

[0146] (i) Gain access to the vasculature through the groin to the femoral vein. (ii) A guidewire is inserted into the femoral vein. (iii) A guidewire is advanced up the inferior vena cava into the right atrium and into the superior vena cava.

[0147] (iv) Using the guidewire as a guide rail, advance the assembly of the puncture device 900, dilator 1620, and sheath 1630. Remove the guidewire. (v) With the distal tip 912 of the puncture device 900 slightly protruding from the distal tips of the dilator 1620 and sheath 1630, manipulate the assembly so that the distal tip 912 is positioned over the fossa ovalis of the septum.

[0148] (vi) The generator 1640 is turned on and energy is delivered to the tissue in pulses. (vii) Delivering electrical current to tissue via an electrode at the distal tip 912 during a pulse of energy.

[0149] (viii) Once the puncture is complete, the puncture device is advanced from the right atrium to the left atrium. At this point in the procedure, the distal tip 912 is no longer in contact with tissue in the fossa ovalis, and the current flow from the electrode at the distal tip 912 changes (i.e., changes in impedance or dielectric).

[0150] (ix) Detecting a change in electrical properties via a sensor, which causes the generator 1640 to stop delivering energy. (x) The dilator 1620 and sheath 1630 are advanced over the puncture device 900 into the left atrium. The dilator 1620 and puncture device 900 are removed. The sheath 1630 is used to deliver an auxiliary device into the left atrium to complete the procedure.

[0151] A similar procedure may be used in the embodiment described in Figure 13c. The embodiment of lancing device 900 in Figure 13c comprises a wire. In this embodiment of the method, lancing device 900 may be used as a guidewire. The steps of such an embodiment of the method are as follows:

[0152] (i) Gain access to the vasculature through the groin to the femoral vein. (ii) A puncture device 900 with a flexible wire is inserted into the femoral vein. (iii) The puncture device 900 is advanced up the inferior vena cava into the right atrium and into the superior vena cava.

[0153] (iv) Using the puncture device 900 as a guide rail, the dilator 1620 and sheath 1630 assembly is advanced. Steps (v) to (x) are the same as in the above method.

[0154] In an alternative method, access to the right atrium is achieved through the superior vena cava using the embodiment of the puncture device depicted in Figure 13c. The embodiment of the puncture device 900 of Figure 13c may comprise a wire and be used as a guidewire. In such methods, a steerable sheath is often used. The steps of such a method are as follows:

[0155] (i) Gain access to the vasculature through the subclavian vein. (ii) A puncture device 900 with a flexible wire is inserted into the subclavian vein. (iii) The puncture device is advanced through the superior vena cava to the right atrium.

[0156] (iv) Using the puncture device 900 as a guide rail, the dilator 1620 and sheath 1630 assembly is advanced. (v) to (x) are the same as above.

[0157] Another alternative method is to use puncture device 900 to gain access to the pericardial cavity of the heart by puncturing the parietal pericardium. As used herein, parietal pericardium refers to the two outer layers of the pericardium, including both the fibrous pericardium as well as the parietal layer. Such an embodiment of the method involves: (i) advancing the puncture device, the dilator, and the sheath toward the heart; (ii) manipulating the assembly of the puncture device, the dilator, and the sheath such that the distal tip of the puncture device is positioned on the parietal pericardium with the distal tip of the puncture device slightly protruding from the distal tips of the dilator and the sheath, and the energy delivery device and the two electrodes on the distal tip of the puncture device are in contact with tissue of the parietal pericardium; (iii) turning on the generator and delivering a pulse of energy through the energy delivery device to the tissue of the parietal pericardium to puncture the tissue; (iv) during the pulse of energy of step (iii), delivering a current of known voltage through the tissue of the parietal pericardium between two electrodes at the distal tip of the puncture device, the current exiting the puncture device through a first of the two electrodes and returning to the puncture through a second of the two electrodes; (v) upon completing the puncture, advancing the puncture device into the pericardial cavity such that the distal tip of the puncture device is no longer in contact with tissue of the parietal pericardium and there is a change in the value of the electrical characteristic of the current between the electrodes at the distal tip of the puncture device; (vi) detecting a change in the value of the electrical property via the sensor, thereby automatically ceasing delivery of energy by the generator to puncture the tissue.

[0158] In the above embodiment of the method for gaining access to the pericardial space, the electrical property that is changed upon completing the puncture is impedance or dielectric. The above-described embodiments of the present invention are intended to be exemplary only, and the scope of the invention is therefore intended to be limited only by the appended claims.

[0159] It will be appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, can also be provided in combination in a single embodiment. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, can also be provided separately or in any suitable subcombination.

[0160] While the present invention has been described in connection with specific embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications, and variations that fall within the scope of the appended claims. All publications, patents, and patent applications mentioned in this specification are incorporated by reference in their entirety to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference herein. Furthermore, citation or identification of any reference in this application should not be construed as an admission that such reference is available as prior art to the present invention.

Claims

1. 1. A puncture system comprising: The puncture system includes a generator capable of supplying energy for puncturing tissue and a current of a known voltage; The puncture system includes an elongate member having a proximal portion and a distal portion; the proximal portion is configured to be connected to the generator so that energy for puncturing tissue and a current of known voltage are supplied to the elongate member; the distal portion terminates in a distal tip, the distal tip comprising an energy delivery device and two electrodes provided on the energy delivery device, the energy delivery device having a portion covered with an insulating material surrounding the two electrodes such that the two electrodes are electrically isolated from the energy delivery device, the energy delivery device being configured to deliver energy for puncturing, the two electrodes being configured to deliver a current of the known voltage through a material in contact with the distal tip, a first of the two electrodes delivering a current to the material and the current returning to the puncturing system through a second of the two electrodes; the generator includes a generator switch for disabling the supply of energy for puncturing to the energy delivery device at the distal tip when the value detected by the sensor is a value related to blood, based on the value of the current detected by the sensor; Puncture system.

2. The puncture system of claim 1, further comprising a sensor capable of detecting a value of the current between the two electrodes associated with the current flowing through the material in contact with the distal tip, the puncture system having means for communicating the value associated with the current between the two electrodes to the generator.

3. The lancing system of claim 1 , wherein the generator switch is a hardware switch.

4. The lancing system of claim 1 , wherein the generator switch is a software algorithm.

5. The puncture system of any one of claims 1 to 4, wherein the generator switch disables the delivery of energy for puncture when the value detected by the sensor is less than a threshold value and the threshold value is between a value associated with blood and a value associated with tissue.

6. The puncture system according to any one of claims 1 to 5, wherein the generator delivers energy for puncturing tissue in pulses, and the current of the known voltage is delivered to the first of the two electrodes in a gap time between one pulse of energy for puncturing and the next pulse.

7. The lancing system according to any one of claims 1 to 6, wherein the sensor is configured to detect impedance or dielectric.

8. The puncture system according to any one of claims 1 to 7, wherein the elongated member is a flexible wire or a needle.

9. The puncture system according to any one of claims 1 to 8, wherein the two electrodes are located on the centerline of the energy delivery device.

10. The puncture system according to any one of claims 1 to 9, wherein the insulating material is configured to form a flap in tissue during puncture.

11. The puncture system according to any one of claims 1 to 8, wherein the two electrodes are located laterally opposite each other on the sides of the distal tip.

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