Balloon catheter with microporous portion

Abstract

An ablation catheter includes a catheter shaft, a balloon at a distal end of the catheter shaft, and a microporous portion. The balloon is configured to support conductors and electrodes and to contain a fluid. The microporous portion is coupled to the balloon to allow fluid to exit the balloon and includes a plurality of openings configured to prevent large air bubbles from exiting the balloon.

Description

Technical Field

[0001] The present disclosure relates to a medical system and method for ablating a patient's tissue. More specifically, the present disclosure relates to a balloon catheter useful during an ablation procedure.

Background Art

[0002] Ablation procedures are used to treat many different conditions in patients. Ablation can be used to treat cardiac arrhythmias, benign tumors, cancerous tumors, and to control bleeding during surgery. Typically, ablation is achieved via thermal ablation techniques including radiofrequency (RF) ablation and cryoablation. In RF ablation, a probe is inserted into the patient and radiofrequency is transmitted through the probe to the surrounding tissue. The radiofrequency generates heat, which destroys the surrounding tissue and ablates blood vessels. In cryoablation, a hollow needle, i.e., a cryoprobe, is inserted into the patient and a cryogenic heat-conductive fluid is circulated through the probe to freeze and kill the surrounding tissue. RF ablation and cryoablation techniques kill tissue indiscriminately via cell necrosis, which can damage or kill other healthy tissues such as tissue in the esophagus, phrenic nerve cells, and tissue in the coronary artery.

[0003] Another ablation technique uses electroporation. In electroporation, an electric field is applied to cells to increase the permeability of the cell membrane. Electroporation can be reversible or irreversible depending on the strength of the electric field. When electroporation is reversible, the increased permeability of the cell membrane can be used to introduce chemicals, drugs, and / or deoxyribonucleic acid (DNA) into the cells before the cells heal and recover. When electroporation is irreversible, the affected cells are killed by apoptosis.

[0004] Irreversible electroporation can be used as a non-thermal ablation technique. In irreversible electroporation, a short train of high-voltage pulses is used to generate an electric field strong enough to kill cells via apoptosis. In the ablation of cardiac tissue, irreversible electroporation can be a safe and effective alternative to the non-discriminatory killing of thermal ablation techniques such as RF ablation and cryoablation. Irreversible electroporation uses an electric field strength and duration that kills the target tissue but does not permanently damage other cells or tissues (e.g., non-target myocardial tissue, red blood cells, vascular smooth muscle tissue, endothelial tissue, and nerve cells), and can be used to kill target tissue such as myocardial tissue. Planning an irreversible electroporation ablation procedure can be difficult due to the lack of acute visualization or data indicating which tissue has been irreversibly electroporated, in contrast to reversible electroporation. Tissue recovery can occur over minutes, hours, or days after the ablation is complete.

Summary of the Invention

[0005] As described in the examples, Example 1 is a catheter for ablation. The catheter includes a catheter shaft, a balloon at the distal end of the catheter shaft, and a microporous portion. The balloon is configured to support a conductor and an electrode and to contain fluid. The microporous portion is coupled to the balloon and is configured to allow fluid to flow out of the balloon and includes a plurality of openings configured to prevent bubbles having a diameter greater than 50 microns from exiting the balloon.

[0006] Example 2 is the catheter described in Example 1, wherein the microporous portion forms part of the balloon.

[0007] Example 3 is the catheter described in any one of Examples 1 and 2, wherein the microporous portion of the balloon is a disc-shaped portion disposed at the distal portion of the balloon.

[0008] Example 4 is the catheter according to any one of Examples 1 to 3, wherein the balloon includes a microporous strip portion having a plurality of openings.

[0009] Example 5 is the catheter according to any one of Examples 1 to 4, wherein the entire balloon is microporous with a plurality of openings.

[0010] Example 6 is the catheter according to any one of Examples 1 to 5, wherein the catheter further includes a tubular portion connected to the shaft and the balloon, and the microporous portion is integrated within the tubular portion.

[0011] Example 7 is the catheter according to any one of Examples 1 to 6, wherein each of the plurality of openings has a diameter of 0.05 microns to 50 microns.

[0012] Example 8 is the catheter according to any one of Examples 1 to 7, wherein the microporous portion is configured such that at a balloon operating pressure of 1 psi (6.9 kPa), fluid exits the balloon at an operating flow rate of 1 ml / min or less.

[0013] Example 9 is the catheter according to any one of Examples 1 to 8, wherein the microporous portion is configured such that at a balloon extraction pressure of at least 10 psi (69 kPa), the fluid exiting the balloon increases to an extraction flow rate of at least 5 ml / min.

[0014] Example 10 is the catheter according to any one of Examples 1 to 9, wherein the balloon is made of at least one of Pebax, nylon, urethane, and polyester.

[0015] Example 11 is the catheter according to any one of Examples 1 to 10, wherein the microporous portion is made of at least one of polytetrafluoroethylene, polypropylene, polycarbonate, Pebax, urethane, polyester, and nylon.

[0016] Example 12 is a catheter according to any one of Examples 6 to 11, in which the microporous portion is integrated into either the hub of the tubular portion or the guide wire lumen.

[0017] Example 13 is a method of manufacturing a catheter configured for ablation. The method includes forming a microporous portion, forming a balloon including attaching the microporous portion, attaching a conductor to the balloon, and attaching the balloon assembly to the catheter.

[0018] Example 14 is the method according to Example 13, wherein in the step of attaching the microporous portion, the microporous portion includes a plurality of openings having a diameter in the range of 0.05 microns to 50 microns.

[0019] Example 15 is the method according to any one of Examples 13 and 14, wherein a plurality of openings of the microporous portion are configured such that the flow of the substance exceeds 0 mL / min and passes through the microporous portion at a flow rate of 1 mL / min or less at the nominal operating pressure.

[0020] Example 16 is an ablation catheter. The catheter includes a catheter shaft, a balloon at the distal end of the catheter shaft, and a microporous portion. The balloon is configured to support a conductor and an electrode and is configured to contain a fluid. The microporous portion is coupled to the balloon and includes a plurality of openings configured to allow fluid to flow out of the balloon and configured to prevent bubbles having a diameter greater than 50 microns from exiting the balloon.

[0021] Example 17 is the catheter according to Example 16, wherein the microporous portion forms part of the balloon.

[0022] Example 18 is the catheter according to Example 17, wherein the microporous portion of the balloon is a disc-shaped portion disposed at the distal portion of the balloon.

[0023] Example 19 is the catheter according to Example 17, wherein the balloon includes a microporous strip portion having a plurality of openings.

[0024] Example 20 is the catheter according to Example 17, wherein the entire balloon is microporous and has a plurality of openings.

[0025] Example 21 is the catheter according to Example 16, wherein the catheter further includes a tubular portion connected to the shaft and the balloon, and the microporous portion is integrated with the tubular portion.

[0026] Example 22 is the catheter according to Example 21, wherein the microporous portion is integrated with either the hub of the tubular portion or the guide wire lumen.

[0027] Example 23 is the catheter according to Example 16, wherein each of the plurality of openings has a diameter of 0.05 microns to 50 microns.

[0028] Example 24 is the catheter according to Example 16, wherein the microporous portion is configured such that at a balloon operating pressure of 1 psi (6.9 kPa), fluid exits the balloon at an operating flow rate of 1 ml / min or less.

[0029] Example 25 is the catheter according to Example 24, wherein the microporous portion is configured such that at a balloon extraction pressure of at least 10 psi (69 kPa), the extraction flow rate of the fluid exiting the balloon increases to at least 5 ml / min.

[0030] Example 26 is the catheter according to Example 16, wherein the microporous portion is made of at least one of polytetrafluoroethylene, polypropylene, polycarbonate, Pebax, urethane, polyester, and nylon.

[0031] Example 27 is a method of manufacturing a catheter configured for ablation. The method includes forming a microporous portion, forming a balloon that includes attaching the microporous portion, attaching a conductor to the balloon, and attaching the balloon assembly to the catheter.

[0032] Example 28 is the method according to Example 27, wherein the step of attaching the microporous portion includes the microporous portion having a plurality of openings with diameters in the range of 0.05 microns to 50 microns.

[0033] Example 29 is the method according to Example 28, wherein the plurality of openings of the microporous portion are configured such that the flow of a substance passes through the microporous portion at a flow rate greater than 0 mL / min and less than or equal to 1 mL / min at the nominal operating pressure.

[0034] Example 30 is the method according to Example 29, wherein the nominal operating pressure is 1 psi (6.9 kPa).

[0035] Example 31 is the method according to Example 27, further including attaching an electrode to the balloon.

[0036] Example 32 is the method according to Example 27, wherein attaching the microporous portion includes sealing the microporous portion onto the balloon.

[0037] Example 33 is a method of using a system for ablation, the method including inserting a catheter having a shaft and a balloon into a patient, manipulating and extending the catheter so that the catheter contacts the patient's heart tissue, performing an ablation treatment on the heart tissue via an electrode, and withdrawing the catheter so that fluid passes through the plurality of openings of the balloon at a flow rate configured to prevent bubbles having a diameter greater than the maximum value from passing through the balloon.

[0038] Example 34 is the method according to Example 33, in which during the retraction step, fluid passes through a plurality of openings of the balloon at a flow rate greater than 0 mL / min.

[0039] Example 35 is that during the retraction step, as the operating pressure of the balloon increases, the flow rate of the fluid increases.

Brief Description of the Drawings

[0040]

Figure 1

Figure 2A

Figure 2B

Figure 3

Figure 4

Figure 5

[0041] Although the present disclosure can accept various changes and alternative forms, specific embodiments are shown as examples in the drawings and will be described in detail below. However, the intention is not to limit the present disclosure to the specific embodiments described. On the contrary, the present disclosure is intended to cover all changes, equivalents, and alternative forms that fall within the scope of the present disclosure as defined by the appended claims.

Modes for Carrying Out the Invention

[0042] FIG. 1 is a schematic diagram showing an exemplary clinical setting 10 for treating a patient 20 using an electrophysiology system 50 and for treating the heart 30 of the patient 20, according to an embodiment of the subject matter of the present disclosure. The electrophysiology system 50 includes a catheter system 60 and an electroanatomical mapping (EAM) system 70. The EAM system 70 includes a location field generator 80, a mapping and navigation controller 90, and a display 92. Also, the clinical setting 10 includes additional equipment such as an imaging device 94 (shown by a C-arm), and various controller elements such as a foot controller 96 configured to enable an operator to control various aspects of the electrophysiology system 50. As will be understood by those skilled in the art, the clinical setting 10 may have other components and arrangements of components not shown in FIG. 1.

[0043] The catheter system 60 can be used for a wide variety of procedures, including various ablation procedures. In the various embodiments described below, the catheter system 60 is an electroporation system. As will be apparent, the aspects of the following description are in the context of an electroporation system, but have applicability to other balloon catheter procedures, including other ablation procedures. The electroporation catheter system 60 includes an electroporation catheter 105, an introducer sheath 110, and an electroporation console 130. In addition, the electroporation catheter system 60 includes various connection elements, such as cables and umbilicals, that operate to functionally connect the components of the electroporation catheter system 60 to each other and to the components of the EAM system 70. This arrangement of connection elements is not critically important to the present disclosure, and those skilled in the art will recognize that the various components described herein can be interconnected in various ways.

[0044] In an embodiment, the electroporation catheter system 60 is configured to deliver electric field energy to target tissue within a patient's heart 30, cause tissue apoptosis, and render the tissue incapable of conducting electrical signals. Also, as described in more detail below, the electroporation catheter system 60 generates a graphic display of the electric field that can be generated using the electroporation catheter 105 based on a model of the electric field, and overlays the graphic display of the electric field on an anatomical map of the patient's heart on the display 92 to assist a user in planning ablation by the irreversible electroporation method using the electroporation catheter 105 before delivering energy. In an embodiment, the electroporation catheter system 60 is configured to generate a graphic display of the electric field based on the characteristics of the electroporation catheter 105 and the position of the electroporation catheter 105 within the patient 20, such as within the patient's heart 30. In an embodiment, the electroporation catheter system 60 is configured to generate a graphic display of the electric field based on the characteristics of the electroporation catheter 105, the position of the electroporation catheter 105 within the patient 20, such as within the patient's heart 30, and the characteristics of the tissue surrounding the catheter 105, such as the measured impedance of the tissue.

[0045] The electroporation console 130 is configured to control the functional aspects of the electroporation catheter system 60. In embodiments, the electroporation console 130 is configured to provide one or more of the following: modeling the electric fields that can be generated by the electroporation catheter 105 (which often involves considering the physical characteristics of the electroporation catheter 105, including the electrodes and the spatial relationships of the electrodes on the electroporation catheter 105), generating a graphical display of the electric fields (which often involves considering the position of the electroporation catheter 105 within the patient 20 and the characteristics of the surrounding tissue), and overlaying the generated graphical display onto an anatomical map on the display 92. In some embodiments, the electroporation control console 130 is configured to generate an anatomical map. In some embodiments, the EAM system 70 is configured to generate an anatomical map for display on the display 92.

[0046] In embodiments, the electroporation console 130 includes one or more controllers, microprocessors, and / or computers that execute code from memory to control and / or execute the functional aspects of the electroporation catheter system 60. In embodiments, the memory can be part of one or more controllers, microprocessors, and / or computers and / or part of a memory capacity accessible via a network such as the World Wide Web.

[0047] In embodiments, the introducer sheath 110 is operable to provide a delivery conduit through which the electroporation catheter 105 can be deployed to a specific target site within the patient's heart 30.

[0048] The EAM system 70 is operable to track the positions of various functional components of the electroperfusion catheter system 60 and generate a high-fidelity three-dimensional anatomical map and an electroanatomical map of a target heart chamber. In an embodiment, the EAM system 70 can be a RHYTHMIA (trademark) HDx mapping system sold by Boston Scientific Corporation. Also, in an embodiment, the mapping and navigation controller 90 of the EAM system 70 includes one or more controllers, microprocessors, and / or computers that execute code from memory to control and / or execute the functional aspects of the EAM system 70, and the memory can be, in an embodiment, part of one or more controllers, microprocessors, and / or computers, and / or part of a memory capacity accessible via a network such as the World Wide Web.

[0049] As will be appreciated by those skilled in the art, the depiction of the electrophysiology system 50 shown in FIG. 1 is intended to provide a general overview of the various components of the system 50 and is in no way intended to lead to the conclusion that the present disclosure is limited to any set of components or arrangement of components. For example, those skilled in the art will readily recognize that additional hardware components, such as breakout boxes and workstations, etc., may be included in, and are likely to be included in, the electrophysiology system 50.

[0050] The EAM system 70 generates a localization field by a field generator 80, defines a localization volume around the heart 30, and enables one or more position sensors or sensing elements on a device to be tracked, e.g., on the electroporation catheter 105, to generate an output that can be processed by the mapping and navigation controller 90 to track the position of the sensor within the localization volume and thus the position of the corresponding device. In the illustrated embodiment, device tracking is achieved using magnetic tracking technology, whereby the field generator 80 is a magnetic field generator that generates a magnetic field defining the localization volume, and the position sensors on the device to be tracked are magnetic field sensors.

[0051] In other embodiments, impedance tracking methods may be employed to track the location of various devices. In such embodiments, the localization field is, for example, an electric field generated by an external field generator arrangement (e.g., surface electrodes), by an in-body or intracardiac device (e.g., an intracardiac catheter), or by both. In these embodiments, the position sensing elements may comprise electrodes on the device to be tracked that generate an output received and processed by the mapping and navigation controller 90 to track the position of various position sensing electrodes within the localization volume.

[0052] In embodiments, the EAM system 70 comprises both magnetic tracking capabilities and impedance tracking capabilities. In such embodiments, the impedance tracking accuracy can be improved in some cases by first creating a map of the electric field induced by an electric field generator within the target heart chamber using a probe equipped with a magnetic position sensor, as may be possible using the aforementioned RHYTHMIA HDx (trademark) mapping system. One exemplary probe is the INTELLAMAP ORION (trademark) mapping catheter sold by Boston Scientific Corporation.

[0053] Regardless of the tracking method used, the EAM system 70 utilizes the position information of various tracked devices along with the cardiac electrical activity obtained, for example, by an electroporation catheter 105 or another catheter or probe equipped with sensing electrodes, to generate a detailed three-dimensional geometric anatomical map or display of the cardiac chambers, as well as an electroanatomical map in which the subject's cardiac electrical activity is superimposed on the geometric anatomical map, and displays it on the display 92. Further, the EAM system 70 can generate a graphic display of various tracked devices within the geometric anatomical map and / or the electroanatomical map.

[0054] Embodiments of the present disclosure integrate an electroporation catheter system 60 with an EAM system 70 to enable a graphic display of the electric field that can be generated by the electroporation catheter 105 to be visualized on an anatomical map of a patient, and in some embodiments, on an electroanatomical map of the patient's heart. Accordingly, the integrated system of the present disclosure has the ability to improve the efficiency of the clinical workflow, including improving the planning of ablation of a portion of a patient's heart by irreversible electroporation. Embodiments of the present disclosure include generating a graphic display of the electric field that can be generated by the electroporation catheter 105, generating an anatomical map, generating an electroanatomical map, and displaying information related to the position and electric field strength of the electric field that can be generated by the electroporation catheter 105.

[0055] In an embodiment, the electroporation catheter 105 is a balloon catheter having electrodes located inside or outside the balloon. The balloon is filled with a substance or fluid such as physiological saline. The catheter 105 includes a microporous portion that can be within the balloon, such as throughout the balloon surface, a strip within the balloon, or within the lumen that allows passage of the catheter 105's hub or guidewire. The microporous portion allows the outflow of the substance used to fill the balloon but does not allow large air bubbles to flow out. Accordingly, any air passing through the microporous portion is effectively dissolved in the bloodstream.

[0056] While many of the drawings and descriptions in this specification describe the use of catheter 105 in connection with ablation by electroporation, the catheters of the present disclosure are not limited to electroporation alone and can be applied to the ablation process in general. The application to electroporation in the present disclosure is an exemplary embodiment of the present disclosure and does not mean to limit the application.

[0057] Figures 2A and 2B are schematic views showing balloon catheter 200 according to an embodiment of the subject matter of the present disclosure. In the embodiment, catheter 200 is used for ablation. This may include ablation by electroporation, including ablation by irreversible electroporation. In the embodiment, catheter 200 includes a plurality of electrodes configured to conduct electricity while being spaced apart from each other. Catheter characteristics are used to model the electric field that can be generated by the catheter. In the embodiment, the characteristics used to model the electric field may include the following (type of catheter (e.g., basket catheter having a constant outer shape after being opened and spline catheter having a variable outer shape that can be opened and closed by a degree), form factor of the catheter (e.g., balloon catheter, basket catheter, and spline catheter), number of electrodes, inter-electrode spacing on the catheter, spatial relationship and orientation of the electrodes (especially with respect to other electrodes on the same catheter), type of material from which the electrodes are made, and shape of the electrodes). In the embodiment, the type of catheter and / or the form factor of the catheter may include catheters such as linear ablation catheters and focal ablation catheters. Here, the type of catheter and / or the form factor of the catheter are not limited to those mentioned in this specification.

[0058] In an embodiment, the catheter 200 is a balloon catheter having electrodes and conductors located inside or outside the balloon. The balloon is filled with a substance or fluid such as physiological saline. In some embodiments, the catheter further comprises a catheter basket configured such that the balloon covers the catheter basket of the catheter 200. In other embodiments, the balloon may be disposed within the catheter basket. As shown, the catheter 200 includes a microporous portion on or within the balloon, such as throughout the balloon surface, a disk-shaped portion of the balloon (e.g., near the distal end), a strip within the balloon, or embodied within the hub of the catheter 200. The microporous portion allows the outflow of the substance used to fill the balloon but does not allow the outflow of air bubbles, such that air passing through the microporous portion is effectively dissolved in the bloodstream and does not cause embolism.

[0059] FIG. 2A is a schematic diagram showing a catheter 200 according to an embodiment of the subject matter of the present disclosure. The catheter 200 includes a catheter shaft 202 and a balloon 222 attached to the catheter shaft 202 at the distal end 228 of the catheter 200. The balloon 222 includes a plurality of openings 216. In some embodiments, the balloon 222 further includes a microporous tube portion having a plurality of openings 216. In an embodiment, the balloon 222 includes a microporous strip portion having a plurality of openings 216. In other embodiments, the entire balloon 222 consists of the openings 216. In various embodiments, the catheter 200 further comprises a hub 212 including a microporous portion.

[0060] In various embodiments, the microporous portion 214 is separately configured and attached to the body of the balloon 222. In an embodiment, the microporous portion is the microporous portion 214 of the aforementioned balloon 222. The microporous portion 214 is configured such that fluid filling the balloon 222 can pass through the balloon 222 at a certain flow rate. Further, the microporous portion 214 is configured to limit the exit of bubbles having a diameter of 50 microns or more from the balloon 222. The balloon 222 is configured such that the fluid filling the balloon 222 expands and dilates the balloon 222.

[0061] In some embodiments, the microporous portion 214 is a disk-shaped portion. In other embodiments, the microporous portion 214 is a strip attached to the balloon 222. In an embodiment, the microporous portion 216 is the entire surface of the balloon 222. The microporous portion 214 consists of a plurality of openings 216 through which fluid can pass, as further described with reference to FIG. 2B. In an embodiment, the balloon catheter 200 is configured to expand to dilate a passage or path in the body that can be occluded or stenosed. Further, in other embodiments, the catheter 200 includes electrodes and conductors and is configured for ablation.

[0062] FIG. 2B shows a perspective view of a catheter 200 including a balloon 222 disposed at the distal end 206 of a catheter shaft 202 and a microporous portion 214 coupled to the balloon 222. In an embodiment, the balloon 222 is configured to contain a fluid 223 and to support electrode groups 208, 210 and a conductor 204. In an embodiment, the conductor 204 includes a flex circuit on the balloon 222. In some embodiments, the balloon 222 includes a hub 212. Further, in an embodiment, the hub 212 includes the microporous portion 214. In an embodiment, the hub 212 is made of a microporous material. In an embodiment, the microporous portion 216 of the hub 212 is a microporous material that is a sintered material or a rolled film. In other embodiments, the microporous portion of the hub 212 consists of expanded PTFE.

[0063] In an embodiment, the microporous portion 214 includes a plurality of openings 216. The plurality of openings 216 are configured such that a substance can flow into and out of the balloon 222. In this embodiment, the plurality of openings 216 include a plurality of pores in the material. In an embodiment, the microporous portion 214 consists of a disk-shaped portion 218. In an embodiment, the microporous portion is formed in a tube portion 220. The tube portion 220 extends from the distal end 224 of the balloon 222 to a position within the space surrounded by the balloon 222 or to a position within the catheter shaft 202. In some embodiments, the tube portion 220 includes both the hub 212 and a guide wire lumen used for introducing a guide wire. In some embodiments, the electrode groups 208, 210 and / or the conductor 204 disposed on the balloon 222 are microporous and include a plurality of openings 216. In an embodiment, the electrodes of the electrode groups 208, 210 and / or the conductor 204 include the microporous portion 214.

[0064] In an embodiment, the microporous portion 214 consists of a microporous material including a plurality of openings 216. In an embodiment, the microporous portion 214 consists of at least one of polytetrafluoroethylene, polypropylene, polycarbonate, Pebax, urethane, polyester, and nylon. In an embodiment, the balloon 222 is formed of at least one of Pebax, nylon, urethane, and polyester. In an embodiment, the material of the balloon 222 is different from the material used for the microporous portion 214.

[0065] The plurality of openings 216 allow a substance such as saline to pass from the inside of the balloon 222 to the outside of the balloon 222, while preventing bubbles, which would otherwise be dangerous to the patient, from exiting the balloon 222. The bubbles prevented from passing through the openings 216 include bubbles having a diameter exceeding a maximum value. In some embodiments, the diameter of the bubbles whose exit from the plurality of openings 216 is restricted is 50 microns or more.

[0066] The substance flows from the balloon 222 at a flow rate affected by the size of the opening 216 or the pore size of the balloon 222 and / or the microporous portion 214. When the substance flows out of the microporous portion 214, an operating pressure is generated within the catheter balloon 222. In some embodiments, this pressure can be greater than 0 psi (0 Pa) and in the range up to 9 psi (62 kPa). In an exemplary embodiment, the operating pressure is about 1 psi (6.9 kPa).

[0067] In embodiments, the size of each of the plurality of openings 216 ranges from 0.05 microns to 50 microns in diameter. In some embodiments, the size of the plurality of openings 216 can range from 0.10 microns to 0.50 microns. In some embodiments, the size of the plurality of openings 216 is 0.45 microns. The flow rate is affected by at least the operating pressure of the balloon 222. In embodiments, the flow rate ranges from 0 mL / min to 1 mL / min, and the balloon 222 operates at an operating pressure of 1 psi (6.9 kPa). In embodiments, when the balloon operates at an operating pressure of 1 psi (6.9 kPa), the flow rate is 0.5 mL / min.

[0068] FIG. 3 is a schematic diagram showing an electroporation catheter 300 adjacent to heart tissue 302 within a patient's heart according to an embodiment of the subject matter of the present disclosure. The heart tissue 302 includes endocardial tissue 304 and myocardial tissue 306, and at least some of the endocardial tissue 304 and myocardial tissue 306 may need to be ablated by methods such as irreversible electroporation. In embodiments, the heart tissue 302 is part of the heart 30 of the patient 20.

[0069] Catheter 300 is suitable for performing ablation of cardiac tissue 302, such as irreversible electroporation. Catheter 300 is not limited to irreversible electroporation and can be used for the application of other ablation methods. Catheter 300 includes a catheter shaft 308 with a distal end 312, electrodes such as the electrodes of a first electrode group 314 and a second electrode group 316, and a balloon 310 configured to support a conductor 332. Catheter 300 further includes a microporous portion 320 at the distal end 326 of catheter 300. In an embodiment, the microporous portion 320 of catheter 300 may be the microporous portion 214 of catheter 200, and the balloon 310 may be the balloon 222 of catheter 200.

[0070] In some embodiments, balloon 310 includes a first electrode group 314 disposed around balloon 310 and a second electrode group 316 disposed adjacent to the distal end 318 of balloon 310. Catheter 300 may comprise variant forms of different electrode and conductor configurations other than those described herein. In an embodiment, each electrode within the first electrode group 314 and each electrode within the second electrode group 316 are configured to conduct electricity and be operably connected to an electroporation console 130. In an embodiment, one or more of the electrodes within the first electrode group 314 and the second electrode group 316 comprise metal. In an embodiment, electroporation catheter 300 and electrodes 314 and 316 are similar to catheter 200 and electrodes 208 and 210 described above herein.

[0071] Catheter 300 and the electrodes 314 of the first electrode group and the electrodes 316 of the second electrode group are or may be operably connected to an electroporation console 130, and the console 130 is configured to provide electrical pulses to electrodes 314 and 316 to generate an electric field capable of ablating cardiac tissue 302 by irreversible electroporation. The amount of electric field provided to cardiac tissue 302 by catheter 300, including the electric field strength and the length of time applied to cardiac tissue 302, determines whether cardiac tissue 302 is ablated.

[0072] For example, an electric field strength of about 400 volts per centimeter (V / cm) is considered to be large enough to ablate heart tissue 302 including myocardial tissue 306 within the heart by irreversible electroporation. On the other hand, an electric field strength of 1600 V / cm or more is required to ablate or kill tissues such as red blood cells, vascular smooth muscle, endothelial tissue, and nerve tissue by irreversible electroporation. Also, reversible electroporation of the heart tissue 302 within the heart can be achieved at an electric field strength of 200 - 250 V / cm.

[0073] Figure 4 is a method 400 for manufacturing a catheter 200 of a system for ablation. In an embodiment, the catheter 200 can be for a system for ablation by electrophoresis. The method is described with reference to the catheter 200 of FIGS. 2A and 2B, but the method is also applicable to the manufacture of the catheter 300 of FIG. 3. In block 402, the method includes forming a microporous portion 214. In an embodiment, the microporous portion 214 consists of at least one of polytetrafluoroethylene, polypropylene, polycarbonate, Pebax, urethane, polyester, and nylon. In an embodiment, the microporous portion 214 includes a microporous disk-shaped portion having a plurality of openings 216. In some embodiments, the microporous portion 214 includes a tube portion having a plurality of openings 216. In an embodiment, the microporous portion 214 includes a microporous strip portion having a plurality of openings 216. In other embodiments, the microporous portion 214 is configured to be a microporous portion configured to cover the entire balloon 222.

[0074] In an embodiment, the microporous portion 214 of step 402 further includes that a plurality of apertures 216 of the microporous portion 214 can have diameters in the range of 0.05 microns to 50 microns. In various embodiments, the plurality of apertures 216 have diameters in the range of 0.05 microns to 1 micron. In an embodiment, the plurality of apertures 216 of the microporous portion 214 of the balloon 222 are configured such that the flow of a substance exits the balloon 222 at a certain flow rate. In an embodiment, the flow rate ranges from a value greater than 0 mL / min to a value of 1 mL / min or less while the balloon is operating at the nominal operating pressure. In an embodiment, this nominal operating pressure within the balloon 222 is about 1 psi (6.9 kPa).

[0075] In block 404, the method further includes forming a balloon, including attaching the microporous portion 214 to the balloon 222. In an embodiment, the balloon 222 is formed from at least one of Pebax, nylon, urethane, and polyester. In an embodiment, attaching the microporous portion 214 to the balloon 222 includes sealing the microporous portion 214 to the balloon 222.

[0076] In block 406, the method further includes attaching the conductor 204 to the balloon 222. This step of attaching the conductor 204 can include attaching the first electrode group 208 and the second electrode group 210 to the balloon 222. In some embodiments, the conductor 204 is a conductive circuit in the form of a flex circuit. In these embodiments, step 406 includes wrapping the flex circuit around the balloon 222. In an embodiment, the flex circuit includes the first electrode group 208 and the second electrode group 210 prior to the attachment step.

[0077] In block 408, the method includes attaching a balloon assembly, which includes a balloon 222 and attached elements such as microporous portion 214, electrode groups 208, 210, and conductor 204, to a catheter 200. In an embodiment, the catheter 200 includes a catheter basket such that the balloon assembly is attached to cover the catheter basket. In other embodiments where a catheter basket is present, the balloon assembly is configured to be disposed within the catheter basket.

[0078] FIG. 5 is a flowchart showing a method of using a catheter of an ablation system according to the present disclosure. The method is described in relation to catheter 200, but catheter 300 can be used similarly in the method. Also, in an embodiment, the heart tissue 302 of FIG. 3 is configured to provide a function in the method of use. Further, elements of the EAM system 70 can be configured to provide functions for various steps of the method of use.

[0079] At 502, the method first includes inserting the catheter 200 into a patient. At 504, the method further includes the step of manipulating and extending the catheter 200 to reach the heart tissue 302 as shown in FIG. 3. In an embodiment, this step further includes determining the positions of the electrodes of the electrode groups 208, 210 with respect to the heart tissue 302 and determining the depth and surface area of the tissue that needs to be ablated. In an embodiment, this step further includes inflating the balloon 222 of the catheter 200 with a fluid. In an embodiment, the fluid is saline.

[0080] At 506, the method 500 further includes performing an ablation treatment of the tissue via the electrodes 208 and / or 210. As described with reference to FIG. 3, the amount of voltage supplied during the treatment can be controlled by the console 130 shown in FIG. 1. Although described with reference to ablation by electrophoresis, the ablation treatment performed can be of different types of ablation treatments.

[0081] At 508, the method includes retracting the catheter 200 such that there is a flow of fluid through the microporous portion 214 of the balloon 222 at a certain flow rate. During operation of the catheter 200, an operating pressure value that can affect the flow rate is present within the balloon 222. In embodiments, the operating pressure ranges from a value greater than 0 psi (0 kPa) to a value of 9 psi (62 kPa). Under nominal operating conditions, the operating pressure can be 1 psi (6.9 kPa). In some embodiments, the flow rate ranges from greater than 0 mL / min to a value of 1 mL / min or less, and the operating pressure is about 1 psi (6.9 kPa). In embodiments, the flow rate increases with an increase in the operating pressure within the balloon 222. In embodiments, during the retraction step, the operating pressure of the balloon 222 is 10 psi (69 kPa), and the flow rate increases to at least 5 mL / min. The microporous portion 214 includes a plurality of openings 216 through which fluid flows. The plurality of openings 216 of the microporous portion 214 are configured to prevent bubbles having a diameter exceeding a specific value from passing through the balloon 222 during the retraction step. In certain embodiments, the value of the diameter is the diameter of each of the plurality of openings 216. In various embodiments, the diameter of the openings 216 is 50 microns or less. In various embodiments, the diameter of the openings 215 is from 0.05 to 0.5 microns. Further, in embodiments, at 508, this step includes enabling the ability of the fluid to pass through the plurality of openings 216 during retraction of the catheter 200 to increase the operating pressure while maintaining the structural integrity of the balloon 222.

[0082] "Example 1" In an example consistent with embodiments of the present disclosure, a surgical catheter is described. This example is described with reference to the catheter 200 of FIG. 2A, but can be applied to the catheter 300 of FIG. 3.

[0083] The catheter 200 includes a balloon 222 and a microporous portion 214 attached on the balloon 200. In this example, the material forming the microporous portion 214 consists of nylon. The surface area of the microporous portion 214 used is 0.32 cm 2It is so. The diameter of each of the plurality of openings 216 of the microporous portion 214 is about 0.45 microns.

[0084] During operation, a fluid such as physiological saline flows into the balloon 222 of the catheter 200, and a part of the fluid can flow out from the plurality of openings 216 of the microporous portion 214 at a certain flow rate. During the operation of the catheter 200, an operating pressure exists within the balloon 222. This affects the flow rate of the physiological saline exiting from the plurality of openings 216. In this example, the operating pressure within the balloon 222 is about 1 psi (6.9 kPa), and the flow rate of the physiological saline exiting from the balloon 222 is about 0.5 mL / min. To minimize the amount of fluid placed within the patient's bloodstream, it is desirable that the flow rate of the fluid through the balloon 222 be low.

[0085] While withdrawing the catheter 200 from the patient, the catheter 200 is retracted into the sheath and requires safe withdrawal of the balloon 222. The main means of discharging physiological saline from the catheter 200 during withdrawal is through the handle of the catheter 200. If some blockage occurs, such as when the physiological saline cannot be discharged through the handle, the operating pressure within the balloon 222 can increase. The microporous portion 214 of the catheter 200 can function as a second means for discharging the physiological saline. The presence of the microporous portion 214 on the balloon 222 can cause an increase in the operating pressure to cause an increase in the flow rate of the fluid exiting the balloon 222 through the microporous portion 214. In this embodiment, an increased operating pressure of 20 psi (138 kPa) during withdrawal of the balloon 222 can result in a flow rate of 10 mL / min. The microporous portion 214 allows for the discharge of the flow so that the pressure does not increase to a value that could cause balloon rupture during withdrawal, which otherwise could result in dangerous bubbles or balloon material being released into the patient.

[0086] The values of this embodiment are exemplary embodiments of the operation of the catheter 200. Other values of these parameters are possible and are not limited to being conditioned on values within the ranges described in this disclosure.

[0087] Without departing from the scope of the present disclosure, various changes and additions can be made to the exemplary embodiments discussed. For example, while the above embodiments refer to specific features, the scope of the present disclosure also includes embodiments having different combinations of features and embodiments that do not include all of the described features. Accordingly, the scope of the present disclosure is intended to embrace all such alternatives, modifications, and variations, together with all of their equivalents, that fall within the scope of the claims.

Claims

**Claim 1** An ablation catheter, comprising: a catheter shaft; and a balloon disposed at a distal end of the catheter shaft, configured to support a conductor and an electrode, and further configured to accommodate a fluid. The balloon includes a hub at a distal end of the balloon, the hub forming a part of the balloon, the hub comprising a disc-shaped microporous portion configured to allow the fluid to flow out of the balloon. The balloon includes a body portion attached to the hub, the body portion being made of a first material, the microporous portion being made of a second material, the second material being different from the first material, the catheter. **Claim 2** The catheter according to claim 1, further comprising a tubular portion connected to the catheter shaft and the balloon, the microporous portion being integrated with the tubular portion, the tubular portion extending to a position within the catheter shaft. **Claim 3** The catheter according to claim 1 or 2, wherein the microporous portion includes a plurality of openings, each of the plurality of openings having a diameter of 0.05 micrometers (microns) to 50 micrometers (microns). **Claim 4** The catheter according to any one of claims 1 to 3, wherein the microporous portion is configured such that at a balloon operating pressure of 1 psi (6.9 kPa), the fluid exits the balloon at an operating flow rate of 1 ml / min or less. **Claim 5** The catheter according to any one of claims 1 to 4, wherein the microporous portion is configured such that at a balloon extraction pressure of at least 10 psi (69 kPa), the extraction flow rate of the fluid exiting the balloon increases to at least 5 ml / min. **Claim 6** The catheter according to any one of claims 1 to 5, wherein the balloon is made of at least one of Pebax, nylon, urethane, and polyester. **Claim 7** The catheter according to any one of claims 1 to 6, wherein the microporous portion is made of at least one of polytetrafluoroethylene, polypropylene, polycarbonate, Pebax, urethane, polyester, and nylon. **Claim 8** The catheter according to claim 2, wherein the microporous portion is integrated with either the hub of the tubular portion or the guide wire lumen.

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