ESTIMATION AND MAPPING OF ABLATION VOLUME

• US 20110152856A1
• Filed: 12/23/2009
• Published: 06/23/2011
• Est. Priority Date: 12/23/2009
• Status: Active Grant

• Current Assignee: Biosense Webster Incorporated (Johnson & Johnson)
• Original Assignee: Biosense Webster Incorporated (Johnson & Johnson)
• Inventors: Govari, Assaf, Altmann, Andres Claudio, Ephrath, Yaron
• Granted Patent: US 8,926,604 B2
• Time in Patent Office: Days
• US Class Current: 606/34
• CPC Class Codes: A61B 18/1492 having a flexible, catheter-like structure, e.g. for heart ablation A61B18/1477 takes precedence
• CPC Class Codes: A61B 18/1815 using microwaves
• CPC Class Codes: A61B 2018/00351 Heart
• CPC Class Codes: A61B 2018/00577 Ablation
• CPC Class Codes: A61B 2018/00702 Power or energy
• CPC Class Codes: A61B 2018/00714 Temperature
• CPC Class Codes: A61B 2018/00761 Duration
• CPC Class Codes: A61B 2018/00791 Temperature
• CPC Class Codes: A61B 2034/104 Modelling the effect of the tool, e.g. the effect of an implanted prosthesis or for predicting the effect of ablation or burring
• CPC Class Codes: A61B 2034/2051 Electromagnetic tracking systems
• CPC Class Codes: A61B 2090/064 for measuring force, pressure or mechanical tension
• CPC Class Codes: A61B 2090/065 for measuring contact or contact pressure
• CPC Class Codes: A61B 34/20 Surgical navigation systems; Devices for tracking or guiding surgical instruments, e.g. for frameless stereotaxis
• CPC Class Codes: A61M 2025/0002 with a pressure sensor at the distal end
• CPC Class Codes: A61M 2025/0166 Sensors, electrodes or the like for guiding the catheter to a target zone, e.g. image guided or magnetically guided
• CPC Class Codes: A61M 25/0158 with magnetic or electrical means, e.g. by using piezo materials, electroactive polymers, magnetic materials or by heating of shape memory materials

Abstract

Tissue ablation systems and methods are provided, wherein a cardiac catheter incorporates a pressure detector for sensing a mechanical force against the distal tip when engaging an ablation site. Responsively to the pressure detector, a controller computes an ablation volume according to relationships between the contact pressure against the site, the power output of an ablator, and the energy application time. A monitor displays a map of the heart which includes a visual indication of the computed ablation volume. The monitor may dynamically display the progress of the ablation by varying the visual indication.

Claims

1. A method of ablation, comprising the steps of:

inserting a probe into a body of a living subject;

urging the probe into contact with a tissue in the body;

determining a mechanical force that is exerted by the probe against the tissue; and

applying a specified dosage of energy for an application time and at a power level to the tissue for ablation thereof, wherein at least one of the application time of the dosage and the power level depend on the mechanical force.

2. The method according to claim 1, further comprising the step of prior to applying the specified dosage of energy, reporting an indication of an expected ablation volume at the power level, the application time and the mechanical force.

3. The method according to claim 1, wherein the probe has a distal end an axis and urging the probe comprises forming an angular deflection of the distal end with respect to the axis.

4. The method according to claim 1, further comprising the steps of calculating an ablation volume of the tissue as a function of the power level, the mechanical force and the application time.

5. The method according to claim 4, further comprising the steps of:

displaying a visual indication of the ablation volume; and

responsively to the visual indication controlling the ablation volume by varying at least one of the power level, the mechanical force and the application time.

6. The method according to claim 1, further comprising the steps of:

calculating a rate of ablation as a function of the power level and the mechanical force; and

controlling the rate of ablation by varying at least one of the power level and the mechanical force.

7. The method according to claim 6, further comprising displaying a visual indication of the rate of ablation, wherein controlling the rate of ablation is performed responsively to the visual indication.

8. The method according to claim 6, further comprising monitoring a temperature of the tissue, wherein controlling the rate of ablation is performed responsively to the temperature.

9. An ablation apparatus, comprising:

a flexible catheter, having a proximal segment, a distal end for insertion into a body cavity of a living subject and a distal tip, which is disposed at the distal end of the catheter and is configured to be brought into contact with a tissue in the body cavity;

a pressure detector for sensing a mechanical force against the distal tip when the distal tip engages the tissue;

an ablator, which applies a given dosage of energy to the tissue so as to ablate the tissue;

a controller, which is responsive to a signal produced by the pressure detector to determine a magnitude of the mechanical force, and to compute an ablation volume using the given dosage of energy and the magnitude of the mechanical force; and

a monitor linked to the controller, which is operative to display a map of the tissue and an indication of the computed ablation volume in the tissue.

10. The ablation apparatus according to claim 9, wherein the controller is operative, prior to an application of the given dosage of energy to cause the monitor to display an indication of an expected ablation volume based on the mechanical force.

11. The ablation apparatus according to claim 9, wherein the controller is operative to receive an operator input comprising a proposed power level and a proposed application time to define the given dosage of energy and to compute a proposed ablation volume using the operator input, and to cause the monitor to display the indication using the proposed ablation volume.

12. The ablation apparatus according to claim 9, wherein the given dosage of energy is delivered at a power level and an application time, wherein the controller is operative to calculate the ablation volume of the tissue as a function of the power level, the mechanical force and the application time.

13. The ablation apparatus according to claim 12, wherein the controller is operative to control a rate of ablation by varying at least one of the power level and the mechanical force.

14. The ablation apparatus according to claim 13, further wherein the controller is operative to cause the monitor to display a visual indication of the rate of ablation.

15. The ablation apparatus according to claim 13, further comprising:

a temperature sensor in the distal end of the catheter for sensing a temperature in the tissue, wherein the controller is operative to control the rate of ablation responsively to the temperature.

16. An ablation apparatus, comprising:

a flexible catheter, having a proximal segment, a distal end for insertion into a body cavity of a living subject and a distal tip, which is disposed at the distal end of the catheter and is configured to be brought into contact with a tissue in the body cavity;

a resilient member, which couples the distal tip to the proximal segment of the catheter and is configured to deform in response to engagement of the distal tip with the tissue;

a position sensor within the catheter for sensing a position of the distal tip relative to the proximal segment of the catheter, and generating signals responsively to changes in response to deformation and orientation of the resilient member;

an ablator, which applies a given dosage of energy to the tissue so as to ablate the tissue;

a controller, which is operative to determine deformation and orientation coordinates of the distal end of the catheter using the signals generated by the position sensor, the controller further operative to determine, responsively to the signals a mechanical force exerted between the distal end of the catheter and the tissue, and to compute an ablation volume using the given dosage of energy and the mechanical force; and

a monitor linked to the controller, which is operative to display a map of the tissue and an indication of the computed ablation volume in the tissue.

17. The ablation apparatus according to claim 16, wherein the controller is operative, prior to an application of the given dosage of energy to cause the monitor to display an indication of an expected ablation volume based on the mechanical force.

18. The ablation apparatus according to claim 16, wherein the distal tip is adapted to form an angular deflection with respect to the proximal segment.

19. The ablation apparatus according to claim 16, wherein the controller is operative to receive an operator input comprising a proposed power level and a proposed application time to define the given dosage of energy and to compute a proposed ablation volume using the operator input, and to cause the monitor to display the indication using the proposed ablation volume.

20. The ablation apparatus according to claim 16, wherein the given dosage of energy is delivered at a power level and an application time, wherein the controller is operative to calculate the ablation volume of the tissue as a function of the power level, the mechanical force and the application time.

21. The ablation apparatus according to claim 20, wherein the controller is operative to control a rate of ablation by varying at least one of the power level and the mechanical force.

22. The ablation apparatus according to claim 21, further wherein the controller is operative to cause the monitor to display a visual indication of the rate of ablation.

23. The ablation apparatus according to claim 21, further comprising:

a temperature sensor in the distal end of the catheter for sensing a temperature in the tissue, wherein the controller is operative to control the rate of ablation responsively to the temperature.