Flexible distal-end assembly for double-sided electrode array and irrigation

Abstract

To provide a medical probe.SOLUTION: A medical probe includes a shaft and an expandable flexible distal-end assembly. The shaft is configured for insertion into a cavity of organ of a patient. The expandable flexible distal-end assembly, which is fitted to a distal-end of the shaft, includes a flat flexible backing sheet, including irrigation channels, and two flexible substrates having respective arrays of electrodes disposed thereon such that each side of the backing sheet has corresponding one of the substrates attached thereto.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates generally to medical probes, and more particularly to multi-electrode catheters. [Background technology]

[0002] Various medical probes having multiple electrodes disposed on their distal end have been proposed in the patent literature. For example, U.S. Patent No. 9,867,978 describes an array of electrodes on a flexible scaffold that can be folded into an axially aligned shape suitable for deployment through a narrow cylindrical channel. The electrode array can be placed within the ventricular system of the brain, forming a minimally invasive platform for precisely localizing electrical activity in space and time within the brain and electrically stimulating brain tissue with precision, diagnosing diseases caused by abnormal electrical activity within the brain, and restoring function.

[0003] As another example, U.S. Patent No. 9,119,533 describes systems, devices, and methods incorporating stretchable or flexible circuits containing arrays of active devices with enhanced sensing, diagnostic, and therapeutic capabilities. The invention allows for conformal sensing contact with target tissue, such as the inner wall of a lumen, the surface of the brain, or the heart. Such direct, conformal contact improves measurement accuracy and therapeutic delivery. Furthermore, the invention allows for the integration of both sensing and therapeutic devices on the same substrate, allowing for faster treatment of diseased tissue and fewer devices to perform the same procedure. Summary of the Invention [Means for solving the problem]

[0004] One embodiment of the present invention, described below, provides a medical probe including a shaft and an expandable, flexible distal tip assembly. The shaft is configured to be inserted into a lumen of a patient's organ. The expandable, flexible distal tip assembly, which is fitted to the distal end of the shaft, includes a flat, flexible backing sheet including an irrigation channel and two flexible substrates on which respective electrode arrays are disposed, one substrate attached to each side of the backing sheet.

[0005] In some embodiments, the irrigation channel is in fluid communication with the surrounding blood.

[0006] In some embodiments, the substrate has openings formed therein for flowing coolant from the irrigation channels to the surrounding blood, hi other embodiments, the irrigation channels are configured to flow coolant in a closed loop.

[0007] In one embodiment, the flexible substrate is a printed circuit board (PCB).

[0008] In some embodiments, at least one of the electrodes is configured to be used interchangeably as an ablation electrode or a sensing electrode.

[0009] In one embodiment, the flat flexible substrate comprises nitinol.

[0010] In another embodiment, the distal end assembly is rectangular.

[0011] According to another embodiment of the present invention, there is also provided a method for manufacturing a medical probe, the method including providing a flat flexible backing sheet including an irrigation channel. Two flexible substrates are fabricated, each with an electrode array disposed thereon. The flexible substrates are attached, one to each side of the backing sheet, to form an expandable flexible distal tip assembly. The expandable flexible distal tip assembly is fitted to the distal end of a shaft for insertion into a lumen of a patient's organ.

[0012] In some embodiments, mating the distal end assembly includes connecting the irrigation channel to a tube extending within the shaft.

[0013] The present invention will be more fully understood from the following detailed description taken in conjunction with the drawings, in which: [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a schematic, pictorial illustration of a catheter-based cardiac diagnostic and ablation system including a double-sided electrode catheter, in accordance with an embodiment of the present invention; [Figure 2A] 2 is an isometric view of a flexible distal tip assembly of the double-sided electrode catheter of FIG. 1, including a cross-sectional view of the assembly layers with irrigation in a closed loop and convective irrigation, according to one embodiment of the present invention. [Figure 2B] 2 is an isometric view of a flexible distal tip assembly of the double-sided electrode catheter of FIG. 1, including a cross-sectional view of the assembly layers with irrigation in a closed loop and convective irrigation, according to one embodiment of the present invention. [Figure 3] 3 is a flow chart that schematically illustrates a method for manufacturing the flexible distal tip assembly of FIG. 2, in accordance with an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] Overview Expandable distal tip assemblies of probes, such as catheters with multiple electrodes, for insertion into the lumen of a patient's organ can be used for various clinical applications, such as electroanatomical mapping and ablation of the lumen wall. The expandable distal tip assembly is coupled to the distal end of the catheter shaft, and in a typical procedure, the catheter is inserted into the lumen (e.g., into a chamber of the heart) through a sheath with the distal tip assembly in a collapsed configuration. After exiting the sheath within the heart, the distal tip assembly assumes its expanded configuration.

[0016] When acquiring diagnostic potentials from the interior surface of a heart chamber, the electrodes disposed on the distal end assembly should be positioned in contact with the chamber wall. Furthermore, to reduce acquisition time and, optionally, to identify the direction of potential propagation, as many electrodes as possible should be placed in contact with the surface simultaneously. When far-field potentials are measured, it is advantageous to have a reference electrode that is close to, but not in contact with, the tissue while the acquisition electrodes are in contact with the tissue. Such a reference electrode can be used, for example, to subtract extraneous far-field potentials from the diagnostic potentials.

[0017] In the present context, far-field bioelectric signals come from regions distant from the tissue region in contact. Typically, such far-field bioelectric signals propagate by conduction through blood and are sensed by both the electrode in contact with the tissue (which senses the "near-field signal" in parallel) and a reference electrode.

[0018] Furthermore, when tissue ablation of a cardiac chamber is required, the electrode used for ablation must be placed in contact with the surface. The effectiveness of ablation can be increased by using multiple electrodes simultaneously placed close to each other and in contact with the surface. For example, in irreversible electroporation (IRE) ablation mode, this configuration increases the strength of the applied electric field and, optionally, locally controls the direction of the electric field to achieve better selectivity for irreversibly electroporating only cardiac cells.

[0019] Basket catheters and balloon catheters, among others, may have multiple electrodes disposed thereon that can simultaneously contact a surface, but the construction of the distal end assemblies for these catheters is complex and costly.

[0020] The embodiments of the invention described below provide an expandable, flexible distal tip assembly configured for sensing and / or ablation that includes two flexible substrates, such as printed circuit boards (PCBs), onto which an electrode array is printed along with conductors to the electrodes. The PCBs are bonded (e.g., cemented) on either side to a flat, flexible Nitinol backing sheet, into which irrigation channels are formed. The PCB / Nitinol combination may be formed with other elements, such as holes to allow blood flow.

[0021] While operating as a sensing electrode, once the distal tip assembly of the catheter emerges from a sheath that is typically pre-placed in the ventricle, one of the distal tip PCBs may be pressed against the heart chamber tissue so that its electrode contacts the tissue, and the electrode on the other PCB may be used for far-field acquisition.

[0022] In some embodiments, the set of electrodes in contact with tissue can be further used for ablation by switching the electrodes to an ablation power source and irrigation channels providing cooling. In one embodiment for IRE ablation, irrigation can be applied to cool the electrode edges to avoid undesirable thermal effects such as charring or coagulum. In another embodiment, in RF ablation mode, irrigation is applied to cool the electrodes to maintain acceptable tissue temperatures.

[0023] Irrigation is achieved by convection, by flowing a coolant (e.g., saline solution) through the blood near the electrodes through openings (e.g., holes) in the PCB connected to the channels. In another embodiment, irrigation is performed within irrigation channels in a closed loop, using thermal conduction to cool the electrodes.

[0024] The disclosed flexible distal tip assembly of a catheter with a double-sided electrode array may enable improved EP diagnosis and ablation in a cost-effective manner with greater efficiency and precision.

[0025] System Description 1 is a schematic, pictorial illustration of a catheter-based diagnostic and ablation system 20 including a double-sided electrode catheter 21, according to one embodiment of the present invention. System 20 is used to determine the position of a flexible distal tip assembly 40 of catheter 21, shown in inset 25, fitted to the distal end of shaft 22, and subsequently ablate targeted cardiac tissue in heart 26.

[0026] As shown in inset 25, the flexible distal end assembly 40 of the catheter shaft 22 is inserted through the sheath 23 and into the heart 26 of a patient 28 lying on a table 29. The proximal end of the catheter 21 is connected to a control console 24.

[0027] In the embodiment described herein, the flexible distal tip assembly 40 carries electrodes 50 on one side of the distal tip assembly for electrophysiological diagnostic purposes, such as sensing arrhythmia activity in tissue within the heart 26 and subsequent IRE ablation of arrhythmogenic tissue. A similar electrode array is disposed on the opposite side of the flexible distal tip assembly 40 (shown in FIG. 2) and is used to acquire parallel far-field potentials. However, the two opposite sides may be functionally reversed depending (e.g., by a system processor) on which side is deemed to be in contact with tissue.

[0028] An expandable frame (e.g., a basket or balloon catheter) carrying diagnostic and far-field sensing electrodes is described in U.S. patent application Ser. No. 16 / 170,631, filed October 25, 2018, entitled "Electrodes on a Double-Sided Printed Circuit Board (PCB) for Cancelling Far-Field Signals," which is assigned to the assignee of the present patent application and which is incorporated by reference, a copy of which is provided in the Appendix.

[0029] The physician 30 navigates the distal end assembly 40 of the shaft 22 to the target location within the heart 26 by manipulating the shaft 22 using a manipulator 32 near the proximal end of the catheter and / or deflection from the sheath 23. During insertion of the shaft 22, the distal end assembly 40 is maintained in a collapsed configuration by the sheath 23. By housing the distal end assembly 40 in a collapsed or folded configuration, the sheath 23 also serves to minimize vascular trauma along the path to the target location.

[0030] To track the position of the diagnostic electrodes 50, multiple external electrodes 27 are coupled to the body of the patient 28. For example, three external electrodes 27 may be coupled to the patient's chest and another three external electrodes may be coupled to the patient's back. (For ease of illustration, only one external electrode is shown in FIG. 1.) In some embodiments, the electrodes 50 sense electrical potentials induced within the heart 26 by applying a voltage between pairs of the external electrodes 27.

[0031] Position tracking techniques similar to those described above, which may also be used to track the position of diagnostic electrodes 50 within heart 26, are described in U.S. patent application Ser. No. 15 / 966,514, entitled "Improved Active Voltage Location (AVL) Resolution," filed April 30, 2018, which is assigned to the assignee of the present patent application and is incorporated by reference, a copy of which is provided in the Appendix.

[0032] Based on the electrical potentials sensed by the electrodes 50, and taking into account the known locations of the external electrodes 27 on the patient's body, the processor 41 calculates an estimated location of at least a portion of the electrodes 50 within the patient's heart. The processor 41 is thus able to associate any given signal, such as an electrophysiological signal received from the diagnostic electrodes 50, with the location at which the signal was obtained.

[0033] Processor 41 is included in control console 24 and is typically a general-purpose computer with suitable front-end and interface circuitry 38 for receiving signals from catheter 21, delivering therapy via catheter 21 at heart 26, and controlling other components of system 20. Processor 41 typically comprises a general-purpose computer along with software programmed to perform the functions described herein. The software may be downloaded to the computer in electronic form, for example, over a network, or alternatively or additionally, may be provided and / or stored on a non-transitory, tangible medium, such as magnetic, optical, or electronic memory.

[0034] In particular, the processor 41 executes dedicated algorithms that enable the processor 41 to perform the disclosed steps, including calculating the positions and respective proximity.

[0035] 1 is chosen solely for conceptual clarity. The techniques of this disclosure can be similarly applied using other system components and configurations. For example, system 20 may include other components and perform non-cardiac diagnostics.

[0036] Flexible distal tip assembly for double-sided electrode array and irrigation 2A and 2B are isometric views of the flexible distal tip assemblies 40 and 42 of the double-sided electrode catheter 21 of FIG. 1, including cross-sectional views of the assembly layers with closed-loop irrigation and convective irrigation, in accordance with an embodiment of the present invention. The illustrated embodiment shows only the elements of the disclosed embodiment that enable the disclosed sensing and / or ablation functions. Therefore, additional elements, such as encapsulation of the edges in soft materials to avoid tissue damage, are not shown. Other features or devices that may be located on the assemblies 40 and 42, such as temperature sensors, are omitted for clarity. Finally, the proportions of the assemblies 40 and 42 are distorted to better illustrate the cross-section; in reality, the flexible distal tip assemblies 40 and 42 are typically much thinner compared to their length and width. The design of the actual assembly 40 or 42 balances flexibility (e.g., conformity to the anatomy) with the contact force of the electrode array.

[0037] As shown in FIG. 2A , the assembly 40 includes two PCBs 50, which are printed arrays of electrodes 50. The electrodes are connected to conductors (e.g., wires or metal traces, not shown) that are proximally connected to electrical wires (not shown) that run through the shaft 22. The PCBs are cemented to opposite sides of a flat, flexible Nitinol substrate 62, within which irrigation channels 45 are formed. The irrigation channels may be formed in a variety of ways, for example, as either holes completely surrounded by Nitinol or as depressions in the Nitinol that are covered by one of the PCBs. The irrigation channels are typically connected to tubing that runs within the shaft 22 (not shown).

[0038] 2B, in assembly 42, this is accomplished by convection by flowing coolant (e.g., saline) into the blood near the electrodes through openings 44 in the PCB connected to channels 45. That is, irrigation channels 45 are connected to the surface of PCB 60 with vertical fluid passages 46 extending from PCB 60 to channels 45 (top and bottom).

[0039] The configuration of the distal tip assemblies 40 and 42 shown in FIGS. 2A and 2B is an exemplary configuration chosen solely for conceptual clarity. Any other suitable configuration can be used in alternative embodiments. In an exemplary embodiment, each side of the assembly 50 includes 50 electrodes 50 arranged in a 5 x 10 electrode array. The size of the array in the extended position is 10-20 mm. The thickness of the assembly is approximately 0.1 mm. In the collapsed position within the sheath, the distal tip assembly is typically rolled to a diameter of 3 mm. Alternatively, any other suitable size can be used. Furthermore, the shape of the distal tip assemblies 40 and 42 need not necessarily be rectangular. Other suitable shapes, such as circular or elliptical, can also be used.

[0040] 3 is a flow chart that schematically illustrates a method for manufacturing the flexible distal tip assembly 40 of FIG. 2A, in accordance with one embodiment of the present invention. The manufacturing process begins with printing an array of electrodes 50 onto a flexible PCB in an electrode printing step 70. In a PCB cutting step 72, the PCB is cut to fit the size of the components used on the PCB 60.

[0041] The electrodes 50 are then wired in an electrical wiring step 74. Alternatively or additionally, step 70 may include printing conductors to connect the electrodes 50.

[0042] In a flat substrate fabrication step 76, which may be performed in parallel with steps 70-74, a flat flexible substrate 62 containing irrigation channels 45 is fabricated.

[0043] In an assembly step 78, two PCB components 60 are attached (eg, cemented) to opposite sides of a flat flexible substrate sheet 62 to form the flexible distal end assembly 40, as described above.

[0044] Finally, in a mating step 80, the flexible distal tip assembly 40 is mated to the distal end of the shaft 22, including making the necessary electrical and mechanical connections, so that the assembly 40 can be used medically, as described in FIG.

[0045] The example flowchart shown in Figure 3 has been chosen solely for conceptual clarity: additional steps that may be included, such as polishing the edges or encapsulating the representation in a soft material, are omitted for simplicity of presentation.

[0046] Although the embodiments described herein relate primarily to cardiac applications, the methods and systems described herein may also be used in other medical applications, such as neurology, ENT, and renal denervation.

[0047] It will therefore be understood that the above-described embodiments are given by way of example, and that the present invention is not limited to what has been particularly shown and described above. Rather, the scope of the present invention includes both combinations and subcombinations of the various features described in the foregoing specification, as well as variations and modifications thereof that would occur to one skilled in the art upon reading the foregoing description, and that are not disclosed in the prior art. Documents incorporated by reference into this patent application are to be deemed part of this application, except that if any term is defined in such incorporated document in a way that contradicts the definition given herein, either expressly or impliedly, then only the definition given herein shall be considered.

[0048] [Embodiment] (1) A medical probe, a shaft for insertion into a lumen of a patient's organ; an expandable flexible distal tip assembly fitted to the distal end of the shaft, a flat, flexible backing sheet containing irrigation channels; two flexible substrates having respective electrode arrays disposed thereon, said substrates being attached, one on each side of said backing sheet; a flexible distal tip assembly comprising: A medical probe comprising: (2) A medical probe as described in embodiment 1, wherein the irrigation channel is in fluid communication with the surrounding blood. (3) A medical probe as described in embodiment 2, wherein the substrate has openings formed therein for flowing coolant from the irrigation channel to the surrounding blood. (4) A medical probe as described in embodiment 1, wherein the irrigation channel is configured to flow coolant in a closed loop. (5) The medical probe of claim 1, wherein the flexible substrate is a printed circuit board (PCB).

[0049] (6) A medical probe as described in embodiment 1, wherein at least one of the electrodes is configured to be used interchangeably as an ablation electrode or a sensing electrode. 7. The medical probe of claim 1, wherein the flat, flexible backing sheet comprises nitinol. (8) A medical probe according to claim 1, wherein the distal end assembly is rectangular. (9) A method for manufacturing a medical probe, comprising: providing a flat, flexible backing sheet containing irrigation channels; preparing two flexible substrates each having an electrode array disposed thereon; attaching the flexible substrates, one on each side of the backing sheet, to form an expandable flexible distal end assembly; mating the expandable flexible distal tip assembly to a distal end of a shaft for insertion into a lumen of a patient's organ; A manufacturing method comprising: (10) The manufacturing method of embodiment 9, wherein fitting the distal end assembly includes connecting the irrigation channel to a tube extending within the shaft.

[0050] (11) The manufacturing method of embodiment 9, wherein creating the substrate includes forming openings in the substrate for flowing coolant from the irrigation channels to the surrounding blood. (12) The manufacturing method of claim 9, wherein providing the backing sheet includes providing irrigation channels through which a coolant can flow in a closed loop. (13) The manufacturing method of embodiment 9, wherein preparing the flexible substrate comprises preparing a printed circuit board (PCB). (14) A manufacturing method described in embodiment 9, wherein at least one of the arranged electrodes is configured to be used interchangeably as an ablation electrode or a sensing electrode. 15. The method of claim 9, wherein the flat, flexible substrate comprises nitinol.

Claims

1. A medical probe, a shaft for insertion into a lumen of a patient's organ; an expandable flexible distal tip assembly fitted to the distal end of the shaft, a flat, flexible backing sheet containing irrigation channels; two flexible substrates each having an array of electrodes disposed thereon, the two flexible substrates being attached, one on each side of the flat flexible substrate; an expandable flexible distal tip assembly comprising: Equipped with The medical probe, wherein the expandable flexible distal tip assembly has a flat plate shape.

2. The medical probe of claim 1 , wherein the irrigation channel is in fluid communication with surrounding blood.

3. The medical probe of claim 2 , wherein the two flexible substrates have openings formed therein for allowing coolant to flow from the irrigation channels to the surrounding blood.

4. The medical probe of claim 3 , wherein the irrigation channel is connected to the openings in the two flexible substrates via a vertical fluid passageway extending from the two flexible substrates to the irrigation channel.

5. The medical probe of claim 1 , wherein the two flexible substrates are printed circuit boards (PCBs).

6. The medical probe of claim 1 , wherein at least one of the electrodes is configured to be used interchangeably as an ablation electrode or a sensing electrode.

7. The medical probe of claim 1 , wherein the flat, flexible substrate comprises nitinol.

8. The medical probe of claim 1 , wherein the expandable flexible distal tip assembly is rectangular.

9. A method for manufacturing a medical probe, comprising: providing a flat, flexible backing sheet containing irrigation channels; creating two flexible substrates each having an array of electrodes disposed thereon; attaching the two flexible substrates, one on each side of the flat flexible backing sheet, to form an expandable flexible distal end assembly; mating the expandable flexible distal tip assembly to a distal end of a shaft for insertion into a lumen of a patient's organ; Including, The method of manufacturing, wherein the expandable flexible distal end assembly has a flat plate shape.

10. The method of claim 9 , wherein fitting the expandable flexible distal end assembly includes connecting the irrigation channel to a tube extending within the shaft.

11. The method of claim 9, wherein creating the two flexible substrates includes forming openings in the two flexible substrates for flow of coolant from the irrigation channels to surrounding blood.

12. 12. The method of claim 11, wherein attaching the two flexible substrates, one on each side of the flat flexible backing sheet, comprises connecting the irrigation channels to the openings in the two flexible substrates via vertical fluid passages extending from the two flexible substrates to the irrigation channels.

13. The method of claim 9 , wherein creating the two flexible substrates comprises creating a printed circuit board (PCB).

14. The method of claim 9 , wherein at least one of the positioned electrodes is configured to be used interchangeably as an ablation electrode or a sensing electrode.

15. The method of claim 9 , wherein the flat, flexible substrate comprises Nitinol.

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