Electroporation Catheter Including a Distal Hoop - Patent application

Abstract

The present disclosure provides electroporation catheters capable of forming loops, generally circular, oval, or similarly shaped loops, located at the distal end portion of the catheter shaft within an individual's vascular system. The electroporation catheters of the present disclosure may be delivered into an individual's vascular system in a straight configuration and may be allowed to form a loop once positioned at a desired location. Some embodiments of the present disclosure include electroporation catheters that include a loop member puller wire in a spiral or helical configuration on the inner surface of the distal end portion of the catheter shaft.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to Provisional Application No. 62 / 612,814, filed January 2, 2018, which is incorporated by reference in its entirety.

[0002] The present disclosure relates generally to medical devices for use in the human body. In particular, in many embodiments, the present disclosure relates to unidirectional and bidirectional electroporation catheters that can form a loop on a distal portion of the catheter shaft within an individual's vascular system to improve the overall performance and maneuverability of the catheter shaft and loop during surgery. [Background technology]

[0003] Electrophysiology catheters are used in a variety of diagnostic, therapeutic, and / or mapping, and ablation procedures to diagnose and / or correct atrial arrhythmias, including, for example, ectopic atrial tachycardia, atrial fibrillation, and atrial flutter. Arrhythmias can produce a variety of symptoms, including irregular heart rate, loss of atrioventricular contractile synchrony, and stasis of blood flow within the cardiac chambers, which can lead to a variety of symptomatic and asymptomatic illnesses and even death.

[0004] Typically, a catheter is deployed and manipulated through a patient's vascular system to an intended site, e.g., a site within the patient's heart. The catheter typically has one or more electrodes that can be used, e.g., for cardiac mapping or diagnosis, ablation, and / or other therapy delivery modes, or both. Once at the intended site, the therapy can include, e.g., radio frequency (RF) ablation, cryoablation, laser ablation, chemical ablation, high intensity focused ultrasound ablation, microwave ablation, and / or other ablation therapy. The catheter delivers ablation energy to the cardiac tissue to create one or more lesions in the cardiac tissue. These lesions disrupt undesirable cardiac activation pathways, thereby limiting or preventing errant conduction signals that may be the source of arrhythmias.

[0005] To position the catheter at a desired site within the body, some type of navigation must be used, such as using a mechanical steering mechanism built into the catheter (or introducer sheath). In some instances, a medical practitioner may manually steer and / or use the catheter using the mechanical steering mechanism.

[0006] The ability to selectively deflect the distal tip of the catheter in a desired direction while simultaneously exerting a torque on the proximal end of the catheter to facilitate advancement of the catheter through the patient's vascular system allows a medical practitioner to adjust the direction of advancement of the distal end of the catheter and selectively position a distal portion of the catheter during an electrophysiology procedure. The proximal end of the catheter can be manipulated to guide the catheter through the patient's vascular system. The distal tip can be deflected by a pull wire. The pull wire is attached to the distal end of the catheter and extends proximally to an actuator in a control handle that controls the application of tension to the pull wire. In many cases, the distal tip of the catheter may include a loop member (or a spiral loop member) for further diagnostic and therapeutic applications. Summary of the Invention [Means for solving the problem]

[0007] The present disclosure generally relates to electroporation catheters and electroporation catheter handles that can form a loop located at the distal tip of the catheter shaft within an individual's vascular system, generally a circular loop, an oval loop, or a similarly shaped loop. The electroporation catheters of the present disclosure can be delivered into an individual's vascular system in a straight configuration and can be allowed to form a loop at the distal end portion when positioned at a desired location. Some embodiments of the present disclosure include electroporation catheters that include a loop member pull wire disposed in a spiral or helical configuration on the inner surface of at least the distal end portion of the catheter shaft. Other embodiments of the present disclosure include using a shape memory wire that is formed into a preset configuration that includes a loop member, such that the preset loop member configuration can take shape when inserted into an individual's body. Still other embodiments of the present disclosure include using a temperature sensitive shape memory wire that allows for the formation of a loop member configuration at the distal end at a specific temperature within the individual's body.

[0008] In one embodiment, the present disclosure is directed to an electroporation catheter comprising: (i) a longitudinally extending catheter shaft having a proximal end portion and a distal end portion; (ii) a handle attached to the proximal end portion of the catheter shaft; and (iii) a loop member formed at the distal end portion of the catheter shaft, a loop member pull wire in a spiral configuration on an inner surface of the distal end portion of the catheter shaft, the loop member pull wire attached to an attachment point on the distal end portion of the catheter shaft and an attachment point on the handle.

[0009] In another embodiment, the present disclosure is directed to a method of introducing an electroporation catheter into a pulmonary vein of an individual, the method including the steps of: (i) forming a shape memory wire into a desired preset configuration including a loop member, (ii) introducing the shape memory wire into a delivery shaft, where the shape memory wire has a different configuration within the delivery shaft from the preset configuration, (iii) introducing and positioning the delivery shaft including the shape memory wire into a pulmonary vein of the individual, (iv) removing the delivery shaft from the shape memory wire to allow the shape memory wire to assume its preset configuration including the loop member within the pulmonary vein, and (v) introducing an electroporation catheter including one or more electrodes over the shape memory wire into the pulmonary vein.

[0010] In another embodiment, the present disclosure is directed to a method of introducing an electroporation catheter into a pulmonary vein of an individual, the method including the steps of: (i) forming a shape memory braided tube into a preset configuration including a loop member, the preset configuration being at a temperature of about 35° C. or greater, the shape memory braided tube including a guidewire lumen, (ii) introducing the shape memory braided tube into an outer shaft, the shape memory braided tube having a different configuration within the outer shaft from the preset configuration, the outer shaft including one or more electrodes, (iii) introducing and positioning the outer shaft including the shape memory braided tube over a guidewire into a pulmonary vein of the individual, and (iv) removing the guidewire and allowing the shape memory braided tube to assume its preset configuration such that the outer shaft including the shape memory braided tube and the one or more electrodes assumes a configuration including a loop member.

[0011] In another embodiment, the present disclosure is directed to an electroporation catheter comprising: (i) a longitudinally extending outer catheter shaft having a proximal end portion and a distal end portion; (ii) a handle attached to the proximal end portion of the catheter shaft; and (iii) a shape memory alloy inner shaft disposed within the outer catheter shaft and including a guidewire lumen therein, the shape memory alloy inner shaft having a first configuration at a first temperature and a second configuration at a second temperature higher than the first temperature, the second configuration including a loop member at a distal end of the shape memory alloy inner shaft.

[0012] These and other aspects, features, details, utilities, and advantages of the present disclosure will become apparent from a reading of the following description and claims, and from a review of the accompanying drawings. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic block diagram of a conventional medical system incorporating various embodiments of the present disclosure.

[0014] [Diagram 2] FIG. 1 is a cross-sectional view showing a portion of a catheter shaft including a spiral loop member pull wire according to an embodiment of the present disclosure.

[0015] [Diagram 3] 13A-13D illustrate the formation of a loop member at a distal end portion of a catheter shaft according to the present disclosure. [Figure 4] 13A-13D illustrate the formation of a loop member at a distal end portion of a catheter shaft according to the present disclosure. [Diagram 5] 13A-13D illustrate the formation of a loop member at a distal end portion of a catheter shaft according to the present disclosure. [Figure 6] 13A-13D illustrate the formation of a loop member at a distal end portion of a catheter shaft according to the present disclosure.

[0016] [Figure 7]FIG. 1 illustrates a core wire having a heat-set structure including a loop member for use in an embodiment of the present disclosure.

[0017] [Figure 8] FIG. 5 shows the core wire of FIG. 4 further including a fixation mechanism.

[0018] [Figure 9] FIG. 1 illustrates a heat-sensitive electroporation catheter capable of forming a loop member according to one embodiment of the present disclosure.

[0019] [Figure 10] 1 is a flow diagram illustrating a method of introducing an electroporation catheter into a pulmonary vein of an individual. [Figure 11] 1 is a flow diagram illustrating a method of introducing an electroporation catheter into a pulmonary vein of an individual. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Corresponding reference characters indicate corresponding parts throughout the several views. It will be understood that the drawings are not necessarily to scale.

[0021] The present disclosure provides medical devices including electroporation catheter systems, electroporation catheters, and electroporation catheter handles suitable for use within the human vascular system for known medical procedures, as well as methods utilizing the electroporation catheter systems, catheters, and catheter handles. The electroporation catheter systems, catheters, and catheter handles of the present disclosure include a loop member, such as a circular loop member or other shaped loop member, at the distal end portion of the catheter shaft that may be formed upon entry into the individual's body, i.e., the catheter shaft may be introduced into the individual's vascular system in a straight configuration for ease of steering, and upon reaching a desired location within the individual's body (e.g., a pulmonary vein), the loop member may be formed, thereby improving circular contact between the electrodes and the surrounding tissue. The disclosed embodiments may lead to more consistent and improved patient outcomes. For purposes herein, the present disclosure is generally described in connection with a number of embodiments of a bidirectional catheter including a circular loop member at the distal end portion. However, it is envisioned that the described features and methods in the present disclosure as described herein may be incorporated into any bidirectional or other catheter or other medical device having loop members of another shape (e.g., oval), as would be understood by one of ordinary skill in the art based on the disclosure herein.

[0022] In many embodiments of the present disclosure, the shaft of the electroporation catheter includes a loop member pull wire disposed in a spiral or helical configuration on the inner surface of at least the distal end portion of the catheter shaft. The loop member pull wire may be attached to an attachment point on the distal end of the catheter shaft and an attachment point on the catheter handle, whereby the catheter shaft may be introduced into the individual's vascular system in a straight configuration. Once the distal end portion of the catheter shaft is properly positioned within the vascular system, the loop member pull wire may be actuated, and the spiral or helical configuration of the pull wire, and the force generated by that configuration upon actuation, will form a loop member at the distal end portion of the catheter. Additionally, in many embodiments, this setting allows the loop member to be straightened out before being removed from the individual's vascular system. As described more fully herein, various portions of the catheter shaft may be formed from materials having different degrees of stiffness to further form the desired loop member. Other embodiments described herein may include the use of shape memory alloy wires with preset loop configurations, and temperature sensitive wires also with preset loop configurations, as well as multiple methods of using these catheters.

[0023]

[0013] Referring now to the drawings, Figure 1 is a schematic block diagram of a system 10 for diagnostic purposes, anatomical mapping, electroporation therapy, and / or ablation therapy. Generally, the various embodiments include an electrode assembly disposed at the distal end of a catheter shaft. As used herein, "proximal" refers to the direction toward the end of the catheter that is near the physician, and "distal" refers (generally) within the individual's body in the direction away from the physician.

[0024] The system 10 includes a catheter electrode assembly 12 including at least one catheter electrode configured for use as described below. The electrode assembly 12 is incorporated as part of a medical device, such as a catheter 14, for electroporation therapy, diagnostic, mapping, and / or therapeutic procedures. For example, the electrode assembly 12 may be used for electroporation therapy of tissue 16 within an individual's body 17. In the illustrated embodiment, the tissue 16 includes the heart or cardiac tissue. However, it should be understood that the embodiment may be used to perform electroporation therapy on a variety of other body tissues.

[0025] FIG. 1 also shows a number of return electrodes, designated 18, 20, and 21, which are schematic representations of body connections that may be used by various subsystems included in the overall system 10, such as an ablation generator 26, an electrophysiology (EP) monitor, such as an ECG monitor 28, and a localization and navigation system 30 for visualization, mapping, and navigation of internal body structures. In the illustrated embodiment, the return electrodes 18, 20, and 21 are patch electrodes. It should be understood that only a single patch electrode is depicted diagrammatically (for clarity), and that the subsystems to which these patch electrodes are connected may, and will generally, include more than one patch (body surface) electrode. In other embodiments, the return electrodes 18, 20, and 21 may be any other type of electrode suitable for use as a return electrode, including, for example, one or more catheter electrodes. The return electrodes, which are catheter electrodes, may be part of the electrode assembly 12 or part of a separate catheter (not shown). System 10 may further include a main computer system 32 (including an electronic controller 50 and data storage-memory 52), which may be integrated with system 30 in certain embodiments. System 32 may further include conventional interface components, such as various user input / output mechanisms 34a and a display device 34b, among other components.

[0026] The ablation generator 26 includes a radio frequency (RF) ablation and electroporation generator (not separately shown) to enable the system 10 to be used for RF ablation and electroporation procedures. The ablation generator 26 may be referred to herein as an ablation / electroporation generator 26. In other embodiments, the ablation generator may include other ablation generators that enable the system to perform any other ablation procedures (such as cryoablation). The ablation generator 26 is configured to energize the electrode elements according to an ablation or electroporation energization strategy, which may be predetermined or user selectable. Although illustrated as a single component, the generator 26 may include separate ablation and electroporation generators. In electroporation-induced primary necrosis therapy, the generator 26 may be configured to generate electrical current delivered through the electrode assembly 12 as a pulsed electric field in the form of short duration DC pulses (e.g., 1 nanosecond to a few milliseconds in duration, 0.1 to 20 ms in duration, or any duration suitable for electroporation) between closely spaced electrodes capable of delivering a field strength (i.e., at the tissue site) of approximately 0.1 to 1.0 kV / cm. The amplitude and pulse duration required for irreversible electroporation are inversely proportional. As the pulse duration decreases, the amplitude must be increased to achieve electroporation.

[0027] The electroporation portion of the generator 26, which may also be referred to herein as a DC energy source, is a monophasic electroporation generator 26 configured to generate a series of DC energy pulses that all generate current in the same direction. In other embodiments, the electroporation generator is a biphasic or multiphasic electroporation generator configured to generate DC energy pulses that do not all generate current in the same direction. In some embodiments, the electroporation generator 26 is a monophasic defibrillator. The defibrillator is configured to output energy in the form of DC pulses at selectable energy levels, such as 50 Joules, 100 Joules, 200 Joules, etc. Other embodiments may have greater or lesser energy settings, and the available settings may be the same or different. For successful electroporation, some embodiments utilize a power level of 200 Joules. The electroporation generator 26 may output DC pulses having a peak value of about -1 kilovolts (kV) to about -2 kV at a power level of 200 Joules. In some embodiments, electroporation generator 26 outputs a DC pulse having a peak value of about -1.5 kV to about -2.0 kV. Other embodiments may output any other suitable voltage, including a positive voltage. In some embodiments, the monophasic defibrillator is a Lifepak 9 defibrillator available from Physio-Control, Inc., Redmond, Washington, USA.

[0028] When used in an ablation procedure, the generator 26 outputs radio frequency (RF) energy through the cable 56 to the catheter 14. The RF energy exits the catheter 14 through the electrodes of the electrode assembly 12. The RF energy travels through the patient's body to the return electrode 118. Dissipation of the RF energy within the body increases the temperature adjacent the electrodes, which can cause ablation. In the exemplary embodiments described herein, the system 10 is suitable for use in performing renal denervation. However, it is understood that the system may be used for other treatments without departing from the scope of the present disclosure.

[0029] The selection interface 29 allows the catheter 14 to be selectively connected to the electroporation generator 26 (through the variable impedance 27) or to the localization and navigation system 30 (through the computer system 32). Additionally, the selection interface 29 is operable to selectively couple different electrodes to the electroporation generator or the localization and navigation system 30. In an exemplary embodiment, the selection interface selectively couples certain portions (but not all) of the electrodes to the localization and navigation system 30 during mapping, navigation, etc., and couples all of the electrodes to the electroporation generator 26 during electroporation. Other embodiments may selectively couple all of the electrodes or different groups of electrodes to the electroporation generator or the localization and navigation system 30.

[0030] The variable impedance 27 allows the impedance of the system to be varied to limit arcing from the catheter electrodes of the catheter 14, particularly during an electroporation procedure. Additionally, the variable impedance 27 may be used to modify one or more characteristics of the output of the electroporation generator 26, such as the amplitude, duration, pulse shape, etc. Although illustrated as a separate component, the variable impedance 27 may be incorporated into the catheter 14 or the generator 26. The variable impedance 27 includes one or more impedance elements, such as resistors, capacitors, or inductors (not shown), connected in series, in parallel, or in a combination of series and / or parallel. In the illustrated embodiment, the variable impedance 27 is connected in series with the catheter 14. Alternatively, the impedance elements of the variable impedance 27 may be connected in parallel with the catheter 14 or in a combination of series and parallel with the catheter 14. Additionally, in other embodiments, the impedance elements of the variable impedance 27 are connected in series and / or in parallel with the return electrode 18. Some embodiments include more than one variable impedance 27, each of which may include one or more impedance elements. In such embodiments, each variable impedance 27 may be connected to a different catheter electrode or group of catheter electrodes, allowing the impedance through each catheter electrode or group of catheter electrodes to be varied separately. In other embodiments, the impedance of system 10 need not necessarily be varied, and variable impedance 27 may be omitted. Furthermore, in some embodiments, variable impedance 27 may be selectively or automatically bypassed when not needed, such as when performing an ablation.

[0031] In an exemplary embodiment, the variable impedance is a variable resistance. In some embodiments, the variable impedance 27 includes one or more resistors (not shown) removably connected between the generator 26 and the catheter 14. The resistors may be connected in series, parallel, or any combination of series and parallel connections to generate a desired system impedance. Some or all of the resistors may be added, removed, or connected differently to vary the system impedance. In some other embodiments, the variable impedance 27 is a variable resistor, such as a rheostat or potentiometer. In still other embodiments, the variable impedance 27 includes resistors coupled together by one or more switches to allow the resistors to be selectively switched in and out of connection between the generator 26 and the catheter 14. Such a variable impedance 27 may also be configured to allow some or all of the resistors to be selectively connected in series or parallel to each other. In some embodiments, the variable impedance 27 varies in response to an appropriate control signal from the computer system 32. The resistors may be any suitable type of resistor. In all embodiments, the resistor (or other impedance element) has a relatively high energy rating sufficient to handle the power of the generator 26 without damaging it. In some embodiments, the variable impedance 27 includes an Ohmite PulsEater resistor available from Ohmite Mfg. Co., Warrenville, IL, USA. With continued reference to FIG. 1, as discussed above, the catheter 14 may also include electroporation functionality and, in certain embodiments, ablation functionality (e.g., RF ablation). However, it should be understood that in those embodiments, variations are possible with respect to the type of ablation energy provided (e.g., cryoablation, ultrasound, etc.).

[0032] In the illustrated embodiment, the catheter 14 includes a cable connector or interface 40, a handle 42, and a shaft 44 having a proximal end 46 and a distal end 48. The catheter 14 may also include other conventional components not shown herein, such as a temperature sensor, additional electrodes, and corresponding conductors or leads. The connector 40 provides a mechanical and electrical connection for a cable 56 extending from the generator 26. The connector 40 may comprise conventional components known in the art and is disposed at the proximal end of the catheter 14 as shown.

[0033] The handle 42 provides a place for the physician to hold the catheter 14 and may also provide a means for steering or guiding the shaft 44 within the body 17. For example, the handle 42 may include a means for changing the length of one or more guidewires that extend through the catheter 14 to the distal end 48 of the shaft 44, or other means for steering the shaft 44. Additionally, in some embodiments, the handle 42 may be configured to vary the shape, size, and / or orientation of a portion of the catheter. The handle 42 is also conventional in the art, and it will be understood that the structure of the handle 42 may vary. In an alternative exemplary embodiment, the catheter 14 may be driven or controlled by a robot. Thus, instead of the physician manipulating the handle to advance / retract and / or steer or guide the catheter 14 (and particularly its shaft 44), a robot is used to manipulate the catheter 14. The shaft 44 is an elongated, tubular, flexible member configured to move within the body 17. The shaft 44 is configured to support the electrode assembly 12 as well as certain associated conductors and possibly additional electronics used for signal processing or conditioning. Shaft 44 may also be capable of carrying, delivering, and / or removing fluids (including irrigation fluids and bodily fluids), medications, and / or surgical tools or instruments. Shaft 44 may be made from conventional materials, such as polyurethane, and defines one or more lumens configured to receive and / or carry conductors, fluids, or surgical tools. Shaft 44 may be introduced into a blood vessel or other structure within body 17 through a conventional introducer. Shaft 44 may then be advanced, retracted, and / or steered or guided through body 17 to a desired location, such as a site of tissue 16, including using a guidewire or other means known in the art.

[0034] In an embodiment of the present disclosure, the catheter 14 is a hoop catheter (sometimes referred to herein as a loop catheter) having catheter electrodes (not shown in FIG. 1) distributed around one or more hoops at the distal end of the shaft 44. The diameter of the hoop (sometimes referred to herein as a "loop") may be variable in some embodiments. In some embodiments, the diameter of the hoop catheter can vary about 10 millimeters (mm) between a minimum diameter and a maximum diameter. In some embodiments, the minimum diameter may be selected at about 13 mm to about 20 mm when the catheter 14 is manufactured. With a variation range of 10 mm, such a catheter would have a maximum diameter of 23 mm to 30 mm. In other embodiments, the hoop diameter can vary from about 15 mm to about 28 mm, from about 13 mm to about 23 mm, or from about 17 mm to about 27 mm. Alternatively, in many embodiments of the present disclosure, the electroporation catheter may be a fixed diameter hoop catheter or may be variable between different diameters.

[0035] In the illustrated embodiment, all of the catheter electrodes are substantially the same. In some embodiments, the catheter 14 has 14 catheter electrodes. In other embodiments, the catheter 14 includes 10 catheter electrodes, 20 catheter electrodes, or any other number of electrodes suitable for performing one or more desired procedures. In some embodiments, the catheter electrodes are ring electrodes, such as platinum ring electrodes. Alternatively, the catheter electrodes may be any other suitable type of electrodes, such as single-sided electrodes or electrodes printed on a curved material. In various embodiments, the catheter electrodes have lengths of 1.0 mm, 2.0 mm, 2.5 mm, and / or any other suitable length.

[0036] In other embodiments, the catheter 14 includes two or more different types of electrodes. The electrode types may differ in size, material, and / or any other suitable characteristic. In some embodiments, the catheter 14 has eight first type catheter electrodes and fourteen second type catheter electrodes grouped into seven pairs of second type catheter electrodes. In other embodiments, the catheter 14 includes any other number of first and second type catheter electrodes suitable for performing electroporation. Additionally, in other embodiments, the ratio of the first type catheter electrodes to the second type catheter electrodes is other than 8:14. A ratio of the first type catheter electrodes to the second type catheter electrodes other than 8:14 may require increasing the size of the catheter shaft. In some embodiments, the catheter electrodes are ring electrodes, such as platinum ring electrodes. Alternatively, the catheter electrodes may be any other suitable type of electrodes, such as single-sided electrodes or electrodes printed on a curved material. In some embodiments, the first type catheter electrodes have a length of 2.5 mm and the second type catheter electrodes have a length of about 1.3 mm. In other embodiments, the first type of catheter electrode has a length between 2.5 mm and 3.1 mm, between 2.2 mm and 3.1 mm, or any other length suitable for use as described herein. In various embodiments, the second type of catheter electrode has a length between 1.0 mm and 1.3 mm, between 0.9 mm and 1.5 mm, or any other length suitable for use as described herein.

[0037] A localization and navigation system 30 may be provided for visualization, mapping, and navigation of internal body structures. The system 30 may comprise conventional devices generally known in the art (e.g., the EnSite NAVX™ navigation and visualization system, commercially available from St. Jude Medical, Inc. and generally described with reference to commonly assigned U.S. Pat. No. 7,263,397, entitled "Method and Apparatus for Catheter Navigation and Location and Mapping in the Heart," the entire disclosure of which is incorporated herein by reference). In various embodiments, the localization and navigation system 30 uses a second type of catheter electrode as a bipolar pair for visualization, mapping, and navigation of internal body structures, as described in more detail below. However, it should be understood that this system is merely exemplary and not limiting in nature. Other techniques are known for positioning / navigating (and visualizing) a catheter in space, including, for example, the CARTO navigation and location system from Biosense Webster, Inc., the AURORA® system from Northern Digital Inc., commercially available fluoroscopy systems, or magnetic location systems such as the gMPS system by Mediguide Ltd. In this regard, some of the localization, navigation, and / or visualization systems involve sensors that generate signals indicative of catheter position information and may include, for example, in the case of impedance-based localization systems, one or more electrodes, or may include one or more coils (i.e., wire windings) configured to detect one or more characteristics of a magnetic field, for example, in the case of magnetic field-based localization systems.

[0038] According to one embodiment of the present disclosure, an electroporation catheter for use in an electroporation system is provided that may be introduced into an individual's vascular system in a straight or substantially uncurved configuration. When the electroporation catheter is properly positioned within the vascular system, a loop at the distal end portion is formed to allow for accurate placement of the loop and improved electrode contact between the loop (including one or more electrodes) and the individual's tissue. The catheter may include one or more lumens for guidewires, fluids, and the like. In this embodiment, all or at least a portion of the distal end portion of the catheter shaft includes at least one loop member pull wire in a spiral or helical configuration that, upon operation, forms a loop member at the distal end portion of the catheter shaft on the inner surface of the catheter shaft. In embodiments where more than one loop member pull wire is utilized, the loop member pull wire may or may not be offset at the inner surface of the distal end portion of the catheter shaft. For example, if two loop member pull wires are used, in one embodiment, they may be offset from each other by 180 degrees around the inner surface of the distal end portion of the catheter shaft. Alternatively, the two loop member pull wires may not be offset at all and may lie substantially adjacent to one another on the inner surface of the distal end portion of the catheter shaft. In many embodiments, the loop member pull wire or wires make at least one, or at least two, or at least three or more revolutions on the inner surface of the distal end portion of the catheter shaft.

[0039] This spiral or helical loop member pull wire present on the inner surface of at least a portion of the distal end portion may be attached to an attachment point on the distal end portion of the catheter shaft and an attachment point on the handle and actuated (to form the desired loop member) by one or more actuation mechanisms on the catheter handle. When actuated, the loop member pull wire is urged toward the proximal end of the catheter, thereby causing the distal end portion of the catheter to form a loop member. The pitch or turns of the spiral or helical loop member pull wire around the inner surface of the distal end portion of the catheter shaft may be controlled, adjusted, and / or configured to control and regulate the diameter and exact size of the loop that is ultimately formed in the distal end portion of the catheter shaft.

[0040] 2, a cross-sectional view of a portion of a longitudinally extending catheter shaft including a helical loop member pull wire is shown, according to one embodiment of the present disclosure. The catheter shaft 100 includes a distal end portion 102, a proximal end portion 104, and a lumen 106. As shown in FIG. 2, the distal end portion 102 of the catheter shaft 100 includes a loop member pull wire 108 configured in a spiral configuration about an inner surface 110 of the distal end portion 102. The loop member pull wire 108 is attached at one end to an attachment point 112 located at the distal end portion 102 of the catheter shaft 100 and at a second end to an attachment point on the catheter handle (not shown in FIG. 2). When the loop member pull wire 108 is energized in a direction along arrow A, the distal end portion 102 of the catheter shaft 100 forms a loop member due to the spiral configuration of the loop pull wire 108 at the distal end portion 102 of the catheter shaft 100, and a torque and twist is applied to the loop pull wire 108 along the shortening direction. The catheter shaft 100 may include one or more electroporation electrodes (not shown in FIG. 2) at the distal end portion 102 of the catheter 100.

[0041] 3A-3D, the formation of a loop member at a distal end portion of a catheter shaft when a force is applied in a proximal direction (arrow A in FIG. 2) in accordance with the present disclosure is illustrated. FIG. 3A illustrates a catheter shaft 200 in a straight configuration including a distal end portion 202 and a proximal end portion 204. The distal end portion 102 further includes an electrode 203. FIGs. 3B, 3C, and 3D illustrate how the catheter shaft 200 forms a loop member 206 (composed of the distal end portion 202) when a loop member pull wire (not shown in FIGS. 3A-3D) is biased in a proximal direction (see arrow A in FIG. 1) by changing the configuration of the distal end portion 202.

[0042] As discussed above, the catheter shaft may be constructed of conventional materials, including, for example, braided polyurethane or similar braided or non-braided materials. The catheter shaft may, in many embodiments, include one or more layers of material in addition to the braided polyurethane to impart additional benefits or properties to the catheter shaft. In some embodiments, these one or more layers may include a layer formed of a polyether block amide material, such as a PEBAX® material. The additional PEBAX® layer may use one or more PEBAX® materials. In one desirable embodiment, the catheter shaft may include one or more polyether block amide material layers that transition from hard to soft along the catheter shaft from the proximal end portion to the distal end portion, i.e., there may be a transition in hardness from the proximal end portion to the distal end portion of the catheter shaft, whereby the one or more polyether block amide material layers present on the catheter shaft include a softer material at the distal end portion of the catheter shaft compared to the proximal end portion of the catheter shaft. Such a transition in hardness or stiffness of the polyether block amide material (or other suitable material or materials) may further facilitate formation of the loop members described herein upon actuation of the loop member pull wire. In one particular embodiment, the catheter shaft may have a hardness of about 70 to about 72 D at the proximal end portion and transition at a hardness of about 30 to about 40 D through the distal end portion, i.e., the stiffness of the catheter shaft decreases from the proximal end portion to the distal end portion to facilitate formation of the loop member. In some embodiments, the stiffness transition may be a gradual transition over a desired length of the catheter shaft.

[0043] The loop member pull wires at least on the inner surface of the distal end portion of the catheter shaft as described herein may be formed from any conventional material, including, for example, stainless steel. In one particular embodiment of the present disclosure, the loop member pull wires are formed from a shape memory alloy, such as a nickel-titanium metal alloy. Such shape memory alloys tend to have a temperature-induced phase change in which the material is heated above a certain transition temperature to induce a change in the layers of the material so that the material assumes a preferred configuration that can be fixed. When the alloy is cooled back down, it "remembers" the shape it had during the heat treatment and tends to assume that configuration unless constrained. One particularly desirable shape memory alloy for use in the present disclosure is Nitinol, a near stoichiometric alloy of nickel and titanium, which may also contain trace amounts of other metals to achieve the desired properties. Nickel-titanium alloys are very highly elastic, commonly referred to as "superelastic" or "pseudoelastic." The elasticity of these alloys helps the formed members return to an expanded configuration for deployment within the body after passing through a distorted or collapsed form of the delivery catheter. Nitinol is a particularly desirable alloy for forming the loop member pull wires.

[0044] Prior to introducing the nickel-titanium metal alloy (or other shape memory alloy) into the inner surface of the distal end portion of the catheter shaft, the alloy may be subjected to a heat treatment process, as known in the art, to impart a shape memory structure to the alloy in the form of a helical or spiral structure, i.e., the nickel-titanium metal alloy is heat set into a helical or spiral structure. After this treatment, the metal alloy is stretched straight (i.e., restrained) and introduced into the distal end portion of the catheter shaft as a loop member pull wire. The heat set structure is not strong enough to allow the metal alloy to form a loop member by itself, i.e., the preset metal alloy remains elongated when introduced into the inner surface of the distal end portion of the catheter shaft. When a proximal force is applied as described herein, the preset metal alloy assists in the formation of the loop member pull wire by the heat treatment or other preset process, i.e., the metal alloy assists in the loop member being formed to achieve its desired heat set structure as it is shaped as described above.

[0045] In many embodiments, a loop member pull wire as described herein may be positioned between two or more tubes of the catheter shaft, such as between an inner tube and an outer tube. In other embodiments, the loop member pull wire may be integral to the design of the wall of the catheter shaft. In many embodiments, the loop member pull wire is brazed, welded, or otherwise secured to a ring or tip of the shaft. In other embodiments, once the loop member pull wire is formed from a fibrous material, it may be secured to a crimped ring or the like. In other embodiments, an adhesive may optionally be used to secure the loop member pull wire. In other embodiments, a second loop member pull wire may be utilized to assist in straightening the catheter shaft and / or to assist in facilitating loop member formation.

[0046] In another embodiment of the present invention, an electroporation catheter capable of forming a loop member at a distal end portion may be introduced into an individual's vascular system in two separate steps, where the core wire is first introduced into the vascular system in a straight configuration and then positioned to form the desired loop member. In this embodiment, the core wire, which may be formed from a shape memory alloy such as a nickel-titanium alloy as described herein, is first subjected to a conventional heat treatment or other suitable treatment to introduce a preset configuration into the core wire. The diameter of the core wire may depend on the outer diameter of the catheter and its associated structures, but is generally about 0.016 inches to about 0.020 inches or less, and in some embodiments may be about 0.010 inches. This preset configuration may include a loop member as described herein, and in some embodiments may be the size of the individual's pulmonary vein sinus. Referring now to FIG. 4, a core wire 300 is shown that has been shaped to include a straight portion 302 and a loop member portion 304.

[0047] This small diameter core wire 300 is then straightened and covered with a small diameter sheath having sufficient strength / stiffness to hold the core wire 300 in a substantially straight configuration (i.e., to constrain the core wire 300) for insertion into the individual's vascular system. This sheathed core wire is then inserted into the individual's vascular system in a straight configuration and guided to a desired location, such as a pulmonary vein. Once positioned at a desired location, the small diameter delivery sheath is removed and the core wire assumes its heat set configuration including a loop member (see FIG. 4) within the individual's vascular system. Once the loop member is formed, an electroporation catheter including one or more electrodes is introduced over the core wire into the vascular system and positioned over the core wire at a desired location for treatment. In some embodiments, the electroporation catheter that has slid over the core wire and assumed the loop member shape may have a durometer value of less than about 50D, or even less than about 40D, or about 35D, so that it is flexible enough to slide over the core wire and assume a shape for treatment.

[0048] Once the electroporation catheter including the electrodes is positioned over the core wire, the electroporation procedure may be performed by the operator. Once the procedure is completed, the electroporation catheter may be removed from the core wire by sliding the electroporation catheter over the core wire and removing it. After the electroporation catheter is removed, the sheath may be introduced over the core wire into a straight configuration as described above so that it can be easily removed from the individual's vascular system.

[0049] In some embodiments of the present disclosure, a core wire as shown in FIG. 4 may further include an anchoring mechanism to help anchor the core wire at a desired location within the vascular system during an electroporation procedure. Referring now to FIG. 5, a core wire 400 is shown including a loop member 402 and an anchoring mechanism 404. FIG. 5 shows a catheter 406 including an electrode 408 positioned over the core wire 400. The anchoring mechanism 404 is sized and configured to anchor the core wire 400 at a desired location within the vascular system, such as within a pulmonary vein ostium. The anchoring mechanism may include one or more central loops (shown in FIG. 5 as central hoops 410 and 412) that aid in anchoring the core wire.

[0050] In another embodiment of the present disclosure, a heat-sensitive electroporation catheter is disclosed that may be introduced into an individual's vascular system in a straight configuration and achieve a desired configuration within the individual's vascular system, including a loop member at the distal portion as described herein, once in a desired location. In this embodiment, the heat-sensitive electroporation catheter includes an outer shaft including one or more electrodes, with a shape-memory alloy (such as a nickel-titanium alloy) tube disposed therein. The shape-memory alloy tube includes a lumen that allows for the delivery of a guidewire therethrough. The outer shaft may be constructed of any suitable catheter shaft material, including, for example, braided and non-braided polyurethane. The shape-memory alloy is preset into a desired configuration including a loop member using a heat treatment or other suitable process. This heat treatment (or other suitable process) sets the shape-memory alloy to assume a configuration including a loop member, i.e., the shape-memory alloy tube is preset to change configuration from a straight configuration at room temperature to a configuration including a loop member at an elevated temperature, such as the individual's body temperature. In some embodiments, the structural change may occur at 30° C., or 31° C., or 32° C., or 33° C., or 34° C., or 35° C. or higher. In these embodiments, when the shape memory alloy tube warms within the individual's body, it assumes the desired structure including the loop member. As described above, a sheath or similar device may be used to re-straighten the loop member and remove it from the body.

[0051] 6, a heat sensitive electroporation catheter 500 is shown in accordance with one embodiment of the present disclosure. The heat sensitive electroporation catheter 500 includes an outer shaft 502 having a proximal end portion 504 and a distal end portion 506. The distal end portion 506 of the heat sensitive electroporation catheter 500 includes electrodes 508, 510, and 512. The heat sensitive electroporation catheter 500 further includes a shape memory alloy tube 514 disposed within the outer shaft 502. The shape memory alloy tube 514 includes a lumen (not shown in FIG. 6) extending therethrough.

[0052] As mentioned above, the present disclosure also relates to a method of introducing an electroporation catheter into a pulmonary vein (or another location) of an individual. In one particular embodiment, the method includes first forming a shape memory wire into a desired preset configuration including a loop member, and introducing the formed shape memory wire into a delivery shaft, where the shape memory wire has a different configuration in the delivery shaft from the preset configuration. Next, the delivery shaft including the shape memory wire is introduced and positioned in the pulmonary vein of the individual, and the delivery shaft is removed from the shape memory wire to allow the shape memory wire to assume the preset configuration including the loop member in the pulmonary vein. Finally, an electroporation catheter including one or more electrodes is introduced over the shape memory wire in the pulmonary vein. Once the electroporation catheter is introduced over the shape memory wire, the electroporation procedure may be completed. This method allows for the formation of a loop member at a distal end portion of the catheter formed in the body.

[0053] 7 is a flow diagram of a method 600 of introducing an electroporation catheter into a pulmonary vein of an individual. The method 600 includes forming a shape memory wire into a desired preset configuration including a loop member in step 602, and introducing the shape memory wire into a delivery shaft, where the shape memory wire has a different configuration in the delivery shaft from the preset configuration in step 604. The method 600 further includes introducing and positioning a delivery shaft including the shape memory wire into a pulmonary vein of an individual in step 606, and removing the delivery shaft from the shape memory wire to allow the shape memory wire to assume its preset configuration including the loop member in the pulmonary vein in step 608. The method 600 further includes introducing an electroporation catheter including one or more electrodes over the shape memory wire in the pulmonary vein in step 610. This method allows for the formation of a loop member at a distal end portion of the catheter formed in the body.

[0054] The present disclosure further relates to another method of introducing an electroporation catheter into a pulmonary vein of an individual. In this particular embodiment, the method includes first forming a shape memory braided tube into a preset configuration including a loop member, the preset configuration being at a temperature of about 35° C. or higher, and the shape memory braided tube including a guidewire lumen. Next, the method includes introducing the shape memory braided tube into an outer shaft, the shape memory braided tube having a different configuration in the outer shaft from the preset configuration, the outer shaft including one or more electrodes. The outer shaft including the shape memory braided tube is introduced and positioned in a pulmonary vein of the individual over a guidewire, and the guidewire is removed. Finally, the shape memory braided tube is allowed to assume its preset configuration, such that the outer shaft including the shape memory braided tube and the one or more electrodes assumes a configuration including a loop member.

[0055] 8 is a flow diagram of a method 700 of introducing an electroporation catheter into an individual's pulmonary vein. The method 700 includes forming a shape memory braided tube into a preset configuration including a loop member, the preset configuration being at a temperature of about 35° C. or greater, the shape memory braided tube including a guidewire lumen, step 702, and introducing the shape memory braided tube into an outer shaft, the shape memory braided tube having a different configuration in the outer shaft from the preset configuration, the outer shaft including one or more electrodes, step 704. The method 700 further includes introducing and positioning the outer shaft including the shape memory braided tube over a guidewire into the individual's pulmonary vein, step 706, and removing the guidewire and allowing the shape memory braided tube to assume its preset configuration, such that the outer shaft including the shape memory braided tube and one or more electrodes assumes a configuration including a loop member, step 708.

[0056] Although certain embodiments of the present disclosure have been described above with a certain degree of particularity, those skilled in the art can make numerous modifications to the disclosed embodiments without departing from the spirit or scope of the present disclosure. All directional references (e.g., upper, lower, upward, downward, left, right, leftward, rightward, top, bottom, upward, downward, vertical, horizontal, clockwise, and counterclockwise) are used solely for a specific purpose to aid the reader in understanding the present disclosure, and do not create limitations, particularly with respect to the location, orientation, or use of the present disclosure. Joint references (e.g., attached, coupled, connected, etc.) should be interpreted broadly and may include intermediate members between the connections of elements, and relative movement between elements. Thus, joint references do not necessarily imply that two elements are directly connected and fixed relative to each other. All matters contained in the above description or shown in the accompanying drawings should be interpreted merely as illustrative and not limiting. Changes in detail or structure may be made without departing from the spirit of the present disclosure, as defined in the appended claims.

[0057] When introducing elements of the present disclosure or preferred embodiments thereof, the articles "a," "an," "the," and "said" are intended to mean that there are one or more of the element. The terms "comprising," "including," and "having" are intended to be inclusive and mean that there may be additional elements other than the listed elements.

[0058] Since various changes may be made in the above-described structure without departing from the scope of the present disclosure, all matter contained in the above description or shown in the accompanying drawings should be interpreted as illustrative and not in a limiting sense. The following items are elements that are claimed in the international application: (Item 1) a longitudinally extending catheter shaft having a proximal end portion and a distal end portion; a handle attached to the proximal end portion of the catheter shaft; 1. An electroporation catheter comprising: a loop member formed at the distal end portion of the catheter shaft; and a loop member pull wire in a spiral configuration on an inner surface of the distal end portion of the catheter shaft, the loop member pull wire attached to an attachment point at the distal end portion of the catheter shaft and an attachment point on the handle. (Item 2) 2. The electroporation catheter of item 1, further comprising one or more electrodes on the catheter shaft. (Item 3) 2. The electroporation catheter of item 1, further comprising a guidewire lumen. (Item 4) 2. The electroporation catheter of claim 1, wherein the loop member pull wire is formed from a shape memory alloy. (Item 5) 5. The electroporation catheter of item 4, wherein the shape memory alloy is a nickel-titanium shape memory alloy. (Item 6) 6. The electroporation catheter of item 5, wherein the loop member pull wire is heat set into a predetermined spiral configuration. (Item 7) 2. The electroporation catheter of item 1, wherein the catheter shaft is formed from a braided material. (Item 8) 8. The electroporation catheter of claim 7, wherein the catheter shaft comprises one or more layers of polyether block amide material. (Item 9) 9. The electroporation catheter of claim 8, wherein the one or more polyether block amide material layers include zones of differing stiffness. (Item 10) 10. The electroporation catheter of claim 9, wherein the distal end portion of the catheter shaft has a different stiffness than the proximal end portion of the catheter shaft. (Item 11) 1. A method of introducing an electroporation catheter into a pulmonary vein of an individual, comprising: forming a shape memory wire into a desired preset configuration including a loop member; introducing the shape memory wire into a delivery shaft, the shape memory wire having a configuration within the delivery shaft that is different from the preset configuration; introducing and positioning the delivery shaft including the shape memory wire into the pulmonary vein of the individual; removing the delivery shaft from the shape memory wire to allow the shape memory wire to assume its preset configuration including the loop member within the pulmonary vein; and introducing an electroporation catheter including one or more electrodes over the shape memory wire into the pulmonary vein. (Item 12) Item 12. The method of item 11, wherein the loop member of the shape memory wire is positioned in a pulmonary vein antrum of the individual. (Item 13) Item 12. The method of item 11, wherein the shape memory wire includes a second loop member sized and configured to anchor the shape memory wire within a pulmonary vein ostium. (Item 14) 12. The method of claim 11, wherein the electroporation catheter comprises one or more electrodes. (Item 15) 12. The method of claim 11, wherein the delivery shaft is formed from a polyether block amide material. (Item 16) Item 16. The method of item 15, wherein the polyether block amide material has a durometer value of about 35. (Item 17) a longitudinally extending outer catheter shaft having a proximal end portion and a distal end portion; a handle attached to the proximal end portion of the catheter shaft; An electroporation catheter comprising: a shape memory alloy inner shaft disposed within the outer catheter shaft and including a guidewire lumen therein, the shape memory alloy inner shaft assuming a first configuration at a first temperature and a second configuration at a second temperature higher than the first temperature, the second configuration including a loop member at a distal end of the shape memory alloy inner shaft. (Item 18) 18. The electroporation catheter of item 17, further comprising one or more electrodes. (Item 19) Item 18. The electroporation catheter of item 17, wherein the outer shaft is formed from a polyether block amide material. (Item 20) Item 18. The electroporation catheter of item 17, wherein the shape memory alloy inner shaft is formed from a nickel-titanium alloy material. (Item 21) 1. A method of introducing an electroporation catheter into a pulmonary vein of an individual, comprising: forming a braided shape-memory tube into a preset configuration including a loop member, the preset configuration being at a temperature of about 35° C. or greater, the braided shape-memory tube including a guidewire lumen; introducing the braided shape memory tube into an outer shaft, the braided shape memory tube having a different configuration within the outer shaft from the preset configuration, the outer shaft including one or more electrodes; introducing and positioning the outer shaft including the shape memory braided tube over a guidewire into a pulmonary vein of the individual; removing the guidewire and allowing the shape memory braided tube to assume its preset configuration such that the shape memory braided tube and the outer shaft including one or more electrodes assume a configuration including a loop member. (Item 22) 22. The method of claim 21, wherein the braided shape memory tube is formed from a nickel-titanium alloy.

Claims

1. a longitudinally extending catheter shaft having a proximal end portion and a distal end portion adjacent the proximal end portion at a boundary; a plurality of electrodes disposed at the distal end portion of the catheter shaft and extending from a proximal electrode to a distal electrode, the proximal electrode being disposed near the boundary; a handle attached to the proximal end portion of the catheter shaft; a loop member pull wire for forming a loop member at the distal end portion of the catheter shaft; Equipped with the loop member pull wire is on an inner surface of the distal end portion of the catheter shaft; one end of the loop member pull wire is attached to an attachment point at the distal end portion of the catheter shaft; the other end of the loop member pull wire is attached to an attachment point on the handle; when the loop member pull wire is untensioned, the proximal end portion and the distal end portion are aligned in a linear configuration along a longitudinal axis, and the loop member pull wire has a spiral configuration that forms a plurality of loops about the longitudinal axis; with the proximal end portion and the distal end portion aligned in the straight configuration, the loop member pull wire transforming adjacent the proximal electrode from a straight pull wire configuration to the spiral configuration forming the plurality of loops; when the loop member pull wire is pulled, the distal end portion of the catheter shaft changes from the straight configuration to form the loop member; the loop member is a complete loop defining a plane generally perpendicular to the longitudinal axis; Electroporation catheter.

2. The electroporation catheter of claim 1 , wherein the plurality of electrodes is at least 10 electrodes.

3. The electroporation catheter of claim 1 or 2, further comprising a guidewire lumen.

4. The electroporation catheter of claim 1 , wherein the loop member pull wire is formed from a shape memory alloy.

5. The electroporation catheter of claim 4, wherein the shape memory alloy is a nickel-titanium shape memory alloy.

6. The electroporation catheter of claim 5 , wherein the loop member pull wire is heat set into a predetermined spiral configuration.

7. The electroporation catheter of claim 1 , wherein the catheter shaft is formed from a braided material.

8. The electroporation catheter of claim 7 , wherein the catheter shaft comprises one or more layers of polyether block amide material.

9. The electroporation catheter of claim 8 , wherein the one or more layers of polyether block amide material include zones of differing stiffness.

10. The electroporation catheter of claim 9 , wherein the distal end portion of the catheter shaft has a different stiffness than the proximal end portion of the catheter shaft.

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