Patent ID: 12239364

DETAILED DESCRIPTION OF EMBODIMENTS

Overview

An expandable frame (e.g., balloon or basket) fitted on a distal end of a catheter may be navigated through the cardiovascular system and inserted into a heart to perform diagnosis and/or ablation of a cardiac tissue using electrodes disposed on the frame.

The multiple electrodes can be used for tasks such as position and/or orientation tracking of the expandable frame, tissue-contact sensing, bipolar electrophysiological (EP) sensing and bipolar irreversible electroporation (IRE) and/or radiofrequency (RF) ablation.

Some of the above tasks, e.g., some forms of contact sensing, EP-sensing and IRE/RF ablation, typically make use of a “return” or “common” electrode. Such an electrode may be fitted on the catheter itself and in that case the sensing and ablation are bipolar. An additional electrode (e.g., a ring electrode) could be fitted on a distal end of a shaft of the catheter, just proximally to the expandable frame, and used as a common or return electrode. However, the need for such a ring electrode complicates the catheter, by adding manufacturing steps and special components and due to the limitations on the collapsed diameter and rigid length, a ring electrode is limited in surface area.

Embodiments of the present invention that are described hereinafter provide expandable frames with a first set of electrodes, called “distal electrodes,” disposed on a distal portion of the expandable frame, and a second set of respective electrodes, called “proximal electrodes,” disposed on a proximal portion of the expandable frame. The distal electrodes can be brought into contact with tissue and used for EP diagnostics and/or ablation. The proximal electrodes are located over the frame such that they are not in contact with tissue, and are jointly used as a return or common electrode.

In some embodiments, the distal and proximal sets of electrodes are arranged in electrode pairs, each pair comprising a distal and proximal electrode. The electrode pair is disposed (e.g., by being attached, plated, printed, deposited or patterned) onto a flexible printed circuit board (PCB). In an embodiment, the proximal set of electrodes is distributed equiangularly about a longitudinal axis of the distal end. For balloon catheters, each PCB is cemented to a balloon membrane. To this end, each of the flexible PCBs has an extended shape such that distal and proximal portions cover distal and proximal regions of the balloon, respectively.

In an embodiment, the proximal electrodes are all electrically interconnected to make one common proximal electrode, to, for example, replace a proximal ring electrode. In another embodiment, the proximal electrodes are selectively connected one with the other.

Typically, the proximal electrodes are interconnected using switching circuitry that can be comprised in interface circuitries, in a switching box, or in an ablation generator. In an embodiment, the proximal electrodes have permanent electrical interconnections by way of conductive links between them.

By providing a technique to realize a proximal common electrode with a flexible PCB, the cost of a one-time use multiple-electrode catheter can be significantly reduced.

System Description

FIG.1is a schematic, pictorial illustration of a catheter-based cardiac diagnostics and/or therapeutic system20comprising a balloon catheter21, in accordance with an embodiment of the present invention. Physician30inserts a shaft22of catheter21through the vascular system of a patient28through a sheath23. The physician then navigates a distal end22aof shaft22to a target location inside a heart26of the patient.

Once distal end22aof shaft22has reached the target location, physician30retracts sheath23and expands balloon40, typically by pumping in saline. Physician30then manipulates shaft22such that a distal set of electrodes50, disposed on balloon catheter40, engage an interior wall of a PV ostium46in a left atrium45, seen in inset25. If a bipolar EP sensor detects a presence of an arrhythmogenic tissue, high-voltage bipolar IRE pulses are then applied to ostium46.

In more detail, due to the flattened shape of the distal portion of balloon40(as seen in inset27), distal electrodes50can be brought in contact with tissue. At the same time, the disclosed set of proximal electrodes52is not in contact with tissue. Some of proximal electrodes52are interconnected together via conductors53, for example by using switching circuitry36of console24, to form the aforementioned common electrode (e.g., for bipolar EP sensing and IRE ablation) that is immersed in blood. Alternatively, all of the proximal electrodes52are connected together via respective conductors53to the switching circuitry36.

Certain aspects of inflatable balloons are addressed, for example, in U.S. Provisional Patent Application 62/899,259, filed Sep. 12, 2019, titled “Balloon Catheter with Force Sensor,” in U.S. patent application Ser. No. 16/726,605, filed Dec. 24, 2019, titled, “Contact Force Spring with Mechanical Stops,” and in U.S. patent application Ser. No. 16/892,514, filed Jun. 4, 2020, titled, “Smooth-Edge and equidistantly spaced electrodes on an expandable frame of a catheter for irreversible electroporation (IRE),” which are all assigned to the assignee of the present patent application and whose disclosures are incorporated herein by reference with a copy in the Appendix.

The proximal end of catheter21is connected to a console24comprising a processor41, typically a general-purpose computer, with suitable front end and interface circuits37for receiving signals from catheter21and from external electrodes49, which are typically placed around the chest of patient26. For this purpose, processor41is connected to external electrodes49by wires running from interface circuits37through a cable39.

Console24further comprises an IRE pulse generator configured to apply bipolar IRE pulses between electrodes50and interconnected proximal electrodes52. Both sets of electrodes are connected to IRE pulse generator38by electrical wiring running in shaft22of catheter21. A memory48of console24stores IRE protocols comprising IRE pulse parameters, such as peak voltage and pulse width.

During a procedure, system20can track the respective locations of electrodes50inside heart26, using the Advanced Catheter Location (ACL) method, provided by Biosense-Webster (Irvine, Calif.), which is described in U.S. Pat. No. 8,456,182, whose disclosure is incorporated herein by reference.

Processor41is typically programmed in software to carry out the functions described herein. The software may be downloaded to the computer in electronic form, over a network, for example, or it may, alternatively or additionally, be provided and/or stored on non-transitory tangible media, such as magnetic, optical, or electronic memory.

In particular, processor41runs a dedicated algorithm as disclosed herein, includingFIG.3, that enables processor41to perform the disclosed steps, as further described below.

In general, in the embodiment described herein, using a first set of distal electrodes50and a second set of proximal electrodes52, both sets being disposed on balloon40of catheter21, system20is capable of performing any of the aforementioned tasks of position and/or ordination tracking of balloon40, tissue-contact sensing, bipolar electrophysiological (EP) sensing, and bipolar irreversible electroporation (IRE) and/or radiofrequency (RF) ablation, such as of PV ostium46tissue of heart26.

The system ofFIG.1is brought by way of example. Proximal electrodes52can therefore be interconnected by circuitries other than circuit36. Switching elements to interconnect electrodes52may be realized by various electronic devices located at various places of the system, including, for example, within catheter21.

In various embodiments, the different interface circuitry and/or switching circuitry elements of the system shown inFIG.1may be implemented using suitable hardware, such as using one or more discrete components (e.g., a solid-state relay) or one or more Application-Specific Integrated Circuits (ASICs).

Printed Proximal Electrodes of a Balloon Catheter

FIG.2is a schematic, pictorial illustration of balloon catheter40used inFIG.1, the balloon catheter comprising distal electrodes50and proximal electrodes52, in accordance with an embodiment of the present invention. InFIG.2, the catheter40extends along a longitudinal axis L-L from a proximal location (closest to an operator) to a distal location furthest away from the operator along the axis L-L. For example, portion42amay be considered with respect to portion42bas a “distal” portion while portion42bmay be considered a “proximal” portion.

Each pair of a distal electrode50and a respective proximal electrode52is disposed on a flexible PCB54that adheres to a membrane42of balloon40. Each distal electrode is connected with a respective conductor51, and each proximal electrode is connected with a respective conductor53. Additional conductors, such as to temperature sensors, and which may together form a conductor ribbon with conductors51/53, are not shown for clarity of presentation.

Conductors51/53are glued (57) at their proximal part (glue layer not shown) to the balloon and are coupled (58) to wires running inside shaft22a(wires not shown).

In the shown embodiment, each of electrodes50and52is connected by its own conductor, for example to a respective wire running to switching circuitry36of system20. To form the aforementioned common electrode, therefore, proximal electrodes52are interconnected by switching circuitry36in console24.

Numerous elements of the balloon are omitted for clarity of presentation. Omitted elements may include, but are not limited to, (i) conductive vias extending through the substrate to electrically couple the electrodes to conductors51and53, (ii) a yarn layer between membrane42and flexible PCB substrate54to lower the risk of delamination or tearing flexible PCB54, and (iii) edge layer of flexible substrate54, added to increase adhesion of flexible substrate54to membrane42, after flexible substrate54is glued to membrane43. Additional functional elements that may be disposed over balloon40, such as temperature sensors and irrigation holes, are also omitted for clarity of presentation.

Printed Proximal Electrodes of a Basket Catheter

FIG.3is a schematic, pictorial illustration of a basket catheter340that can be used with system20of inFIG.1, the basket catheter comprising distal electrodes350and proximal electrodes352, in accordance with an embodiment of the present invention.

InFIG.4, the catheter340extends along a longitudinal axis L-L362from a proximal location (closest to an operator) to a distal location furthest away from the operator along the axis L-L. Catheter340comprises a plurality of expandable spines354disposed about longitudinal axis362. Distal end365of a shaft322can slide on a guidewire360. Guidewire360extends through a lumen in shaft322.

Each pair of a distal electrode350and a respective proximal electrode352is disposed on a flexible PCB355that that adheres to spine354of catheter340. Each distal electrode is connected with a respective conductor351, and each proximal electrode is connected with a respective conductor353. Additional conductors, such as to temperature sensors, and which may together form a conductor ribbon with conductors351/353, are not shown for clarity of presentation.

Conductors351/353are glued (glue not shown) at their proximal part to the inner side of the spines and are coupled to wires running inside shaft a322(wires not shown).

In the shown embodiment, each of electrodes350and352is connected by its own conductor, for example to a respective wire running to switching circuitry36of system20. To form the aforementioned common electrode, therefore, proximal electrodes352are interconnected by switching circuitry36in console24.

Numerous elements of the basket are omitted for clarity of presentation. Omitted elements may include, but are not limited to, (i) conductive vias extending through the spines to electrically couple the electrodes to conductors351and353, (ii) a yarn layer between spines354and flexible PCB substrate355to lower the risk of delamination or tearing flexible PCB355, and (iii) edge layer of flexible substrate355, added to increase adhesion of flexible substrate355to spines354, after flexible substrate355is glued to the spines. Additional functional elements that may be disposed over basket340, such as temperature sensors and irrigation holes, are also omitted for clarity of presentation.

FIG.4is a flow chart that schematically illustrates a method for applying bipolar EP sensing and IRE pulses using balloon (40) catheter21ofFIG.1, in accordance with an embodiment of the invention. The algorithm, according to the presented embodiment, carries out a process that begins when physician30navigates the balloon catheter to a target tissue location in an organ of a patient, such as at PV ostium46, using, for example, electrodes50as ACL sensing electrodes, at a balloon catheter navigation step80.

Next, physician30positions the balloon catheter at ostium46, at a balloon catheter positioning step82. Then physician30fully inflates balloon40to contact target tissue with electrodes50over an entire circumference of PV ostium46, at a balloon inflation step84.

Next, at a switching step86, processor41commands switching circuitry36to interconnect all proximal electrodes52, one with the other, to form a common electrode.

At an EP diagnosis step88, system20acquires bipolar EP potentials between distal electrodes50and the common electrode52over an entire circumference of balloon40to search for arrhythmogenic tissue.

If, at a checking step90, analysis determines that the EP signals are normal, or at least not sufficiently indictive of an EP aberrant tissue, physician30moves the catheter to another cardiac location, at a catheter moving step92, and the process returns to step88.

If, on the other hand, at a checking step90, analysis of the EP signals indicates an arrhythmogenic tissue, physician30operates system20to apply bipolar IRE pulses between distal electrodes50and the common electrode52to ablate tissue over the circumference of balloon40, at an IRE ablation step94, to isolate an arrhythmia.

Although the embodiments described herein mainly address cardiac applications, the methods and systems described herein can also be used in other medical applications, such as in neurology and Oncology.

It will thus be appreciated that the embodiments described above are cited by way of example, and that the present invention is not limited to what has been particularly shown and described hereinabove. Rather, the scope of the present invention includes both combinations and sub-combinations of the various features described hereinabove, as well as variations and modifications thereof which would occur to persons skilled in the art upon reading the foregoing description and which are not disclosed in the prior art. Documents incorporated by reference in the present patent application are to be considered an integral part of the application except that to the extent any terms are defined in these incorporated documents in a manner that conflicts with the definitions made explicitly or implicitly in the present specification, only the definitions in the present specification should be considered.