EP-4740882-A2 - TISSUE ABLATION CATHETER WITH AN INSULATOR BETWEEN INNER AND OUTER ELECTRODES

Abstract

A catheter for tissue ablation with one or more electrodes attached to the inner surface of the catheter body facing the lumen, and one or more electrodes attached to the outer surface. The electrodes are offset from the distal end of the catheter. The material between the inner and outer electrodes is an insulator and may be for example a dielectric with a high dielectric constant. This catheter configuration generates an electric field that bends around the tip of the catheter. The field strength near the catheter tip is relatively symmetric; therefore, tissue ablation depth is relatively insensitive to catheter orientation. Embodiments may have multiple inner or outer electrodes and may switch voltage configurations across electrodes to vary the electric field direction over time, improving ablation consistency.

Inventors

• MICKELSEN, STEVEN

Assignees

• Field Medical, Inc.

Dates

Publication Date

20260513

Application Date

20231211

Claims (15)

1. A system for tissue ablation comprising: an ablation catheter comprising a tubular body having an inner surface, an outer surface, and a distal end, one or more inner electrodes disposed on the inner surface, and one or more outer electrodes disposed on the outer surface; and a controller electrically coupled to the one or more inner electrodes and the one or more outer electrodes, the controller configured to: set voltages of the one or more inner electrodes and the one or more outer electrodes according to a first voltage pattern to generate an electric field having a vector direction; and modify the voltages of the one or more inner electrodes and the one or more outer electrodes to a second voltage pattern thereby changing the vector direction of the electric field.
2. The system of claim 1, wherein in the first voltage pattern, the one or more inner electrodes have a first polarity, and the one or more outer electrodes have a second polarity.
3. The system of claim 1 or 2, wherein in the second voltage pattern, the controller is configured to apply a voltage solely to the one or more outer electrodes, particularly wherein in the second voltage pattern, an outer electrode of the one or more outer electrodes has a first polarity and another one of the one or more outer electrodes has a second polarity.
4. The system of one of claims 1 to 3, wherein the one or more outer electrodes comprises two outer electrodes, and wherein in the first voltage pattern, each of the two outer electrodes have a same polarity.
5. The system of one of claims 1 to 4, wherein the one or more outer electrodes comprises two outer electrodes, and wherein in the second voltage pattern, the two outer electrodes have different polarities.
6. The system of one of claims 1 to 5, wherein in the first voltage pattern, at least one inner electrode of the one or more inner electrodes has a first polarity and in the second voltage pattern, a voltage is not applied to the at least one inner electrode, particularly wherein the first polarity is positive.
7. The system of one of claims 1 to 6, wherein in the first voltage pattern, a voltage is not applied to at least one electrode of the one or more outer electrodes and in the second voltage pattern, the at least one electrode has a first polarity.
8. The system of one of claims 1 to 7, wherein each of the one or more outer electrodes are offset from the distal end of the tubular body along a longitudinal axis of thereof, and/or each of the one or more inner electrodes are offset from the distal end of the tubular body along a longitudinal axis of thereof.
9. The system of one of claims 1 to 8, wherein the controller is configured to switch from the first voltage pattern to the second voltage pattern without repositioning the ablation catheter.
10. The system of one of claims 1 to 9, wherein the controller is further configured to modify the voltages of the one or more inner electrodes and the one or more outer electrodes from the second voltage pattern to a third voltage pattern thereby changing the vector direction of the electric field again, particularly wherein in the first voltage pattern, a voltage is not applied to an outer electrode of the one or more outer electrodes, in the second voltage pattern the outer electrode has a first polarity, and in the third voltage pattern, the outer electrode has the first polarity, more particularly wherein the first polarity is negative.
11. The system of claim 10, wherein the controller is further configured to repeatedly switch between one or more of the first, second, or third voltage patterns.
12. The system of one of claims 1 to 11, wherein an angular difference between the vector directions for the first voltage pattern and the second voltage pattern is between about 1° to about 90°.
13. The system of one of claims 1 to 12, wherein the controller is configured to modify the voltages between the first voltage pattern and the second voltage pattern within a time period ranging from about 10 nanoseconds to about 1 second.
14. The system of one of claims 1 to 13, wherein the tubular body comprises an electrically insulating material, particularly wherein the one or more inner electrodes and the one or more outer electrodes are separated by the electrically insulating material and are configured to form a current path that bends around the distal end of the tubular body when a voltage is applied to the one or more inner electrodes and the one or more outer electrodes.
15. The system of one of claims 1 to 14, wherein the electric field has a symmetrical contour around the distal end of the tubular body.

Description

BACKGROUND OF THE INVENTION FIELD OF THE INVENTION One or more embodiments of the invention are related to the field of medical catheters used for tissue ablation. More particularly, but not by way of limitation, one or more embodiments of the invention enable a tissue ablation catheter with an insulator between inner and outer electrodes. DESCRIPTION OF THE RELATED ART Catheters with attached electrodes are widely used for tissue ablation to address a variety of medical issues. For example, for cardiac applications specialized multielectrode catheters have been invented to deliver electroporation to the ostium of pulmonary veins within the left atrium. Many of these devices are designed to perform anatomic ablation of the pulmonary veins to treat a common arrythmia called atrial fibrillation. Although existing ablation catheters have a wide variety of electrode configurations, they all place electrodes on the outer surface of the catheter, and typically have one electrode at the tip of the catheter. These configurations limit the shape of the electric fields that are generated by these catheters. In particular the electric field contours are typically elongated because they are generated by dipoles aligned with the longitudinal axis of the catheter. These elongated field shapes are not optimal for tissue ablation because ablation depth depends on the orientation of the catheter relative to the tissue to be ablated. For at least the limitations described above there is a need for a tissue ablation catheter with an insulator between inner and outer electrodes. BRIEF SUMMARY OF THE INVENTION One or more embodiments described in the specification are related to a tissue ablation catheter with an insulator between inner and outer electrodes. Embodiments of the invention may generate novel electric field shapes that improve ablation consistency. One or more embodiments of the invention may include a catheter with a tubular element having a longitudinal axis, a distal end, a lumen, an inner surface surrounding the lumen, and an outer surface. There may be an electrical insulator between the inner surface and the outer surface. The catheter may have one or more inner electrodes coupled to the inner surface, and one or more outer electrodes coupled to the outer surface. The inner electrodes and the outer electrodes may each be offset from the distal end of the catheter. The electrical insulator may separate the inner electrodes from the outer electrodes. The distal end of the catheter may be placed near a tissue to ablated. The controller may set the voltages of the inner and outer electrodes to generate an electric field outside the tubular element that induces ablation of the tissue by electroporation. In one or more embodiments of the invention the shortest path of electrical current flowing from an inner electrode to an outer electrode may be longer than the distance between the inner and outer electrode. In one or more embodiments of the invention the electrical insulator may be a dielectric, such as aluminum nitride ceramic for example. In one or more embodiments the conductivity of the electrical insulator may be less than 0.1 micro-Siemens per centimeter. In one or more embodiments the distance between the distal end of the catheter tubular element and each of the inner electrodes may be greater than or equal to 0.01 millimeters and less than or equal to 1 meter. In one or more embodiments the distance between the distal end of the catheter tubular element and each of the outer electrodes may be greater than or equal to 0.01 millimeters and less than or equal to 1 meter. In one or more embodiments of the invention the controller may set a potential difference between at least one inner electrode and at least one outer electrode of greater than 5000 volts. In one or more embodiments of the invention the controller may modify the voltages of the inner and outer electrodes within a pulse time that is less than two times the membrane recovery time of the tissue to be ablated. In one or more embodiments the controller may modify the voltages of the inner and outer electrodes within a period that is less than or equal to 10 milliseconds. In one or more embodiments the controller may modify voltages of the inner and outer electrodes to change the direction of the electric field outside the tubular element over time. For example, the controller may set electrode voltages at one time to generate a first average electric field vector in a region of the tissue to be ablated, and may set electrode voltages at another time to generate a second average electric field vector in a region of the tissue to be ablated, where the angular difference between the first and second average electric field vector is at least 1 degree. BRIEF DESCRIPTION OF THE DRAWINGS The above and other aspects, features and advantages of the invention will be more apparent from the following more particular description thereof, presented in conjunc