System and Method for Adaptive RF Ablation

• US 20120136348A1
• Filed: 04/28/2011
• Published: 05/31/2012
• Est. Priority Date: 11/29/2010
• Status: Active Grant

• Current Assignee: Medtronic Ablation Frontiers LLC (Medtronic Plc)
• Original Assignee: Medtronic Ablation Frontiers LLC (Medtronic Plc)
• Inventors: Condie, Catherine R., Sherman, Marshall L., Kasischke, Kathryn E., Corvi, Timothy J., Strunk, Aaron R.
• Granted Patent: US 9,532,828 B2
• Time in Patent Office: Days
• US Class Current: 606/34
• CPC Class Codes: A61B 18/1206 Generators therefor
• CPC Class Codes: A61B 18/14 Probes or electrodes therefor
• 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 2018/0016 Energy applicators arranged in a two- or three dimensional array
• CPC Class Codes: A61B 2018/00214 Expandable means emitting energy, e.g. by elements carried thereon
• CPC Class Codes: A61B 2018/00267 having a basket shaped structure
• CPC Class Codes: A61B 2018/00351 Heart
• CPC Class Codes: A61B 2018/00577 Ablation
• CPC Class Codes: A61B 2018/00642 with feedback, i.e. closed loop control
• CPC Class Codes: A61B 2018/00648 using more than one sensed parameter
• CPC Class Codes: A61B 2018/00678 upper
• CPC Class Codes: A61B 2018/00702 Power or energy
• CPC Class Codes: A61B 2018/00714 Temperature
• CPC Class Codes: A61B 2018/00726 Duty cycle
• CPC Class Codes: A61B 2018/00779 Power or energy
• CPC Class Codes: A61B 2018/00791 Temperature
• CPC Class Codes: A61B 2090/065 for measuring contact or contact pressure

Abstract

A medical method, device, and system are provided, including advancing an ablation element of a medical device into contact with tissue to be treated, selecting a power level of energy to ablate the tissue, delivering energy at the selected power level to the ablation element, determining whether the ablation element is in continuous contact with the tissue, and reducing the selected power level when the ablation element ceases to be in continuous contact with the tissue.

Claims

1. A medical method, comprising:

advancing an ablation element of a medical device into contact with tissue to be treated;

supplying power to the ablation element to ablate the tissue;

determining whether the ablation element is not in continuous contact with the tissue; and

modifying power supplied to the ablation element based at least in part on the determination that the ablation element is not in continuous contact with the tissue.

2. The medical method of claim 1, wherein the tissue to be treated is cardiac tissue.

3. The medical method of claim 1, further comprising the step of determining whether the ablation element has regained continuous contact with the tissue, and modifying the power supplied to the ablation element upon determination that the ablation element has regained continuous contact with the tissue.

4. The medical method of claim 3, further comprising:

selecting a delay interval; and

increasing the power to the ablation element after the ablation element has regained continuous contact with the tissue for time at least equal to the delay interval.

5. The medical method of claim 4, wherein the selected delay interval is substantially equal to 3 seconds.

6. The medical method of claim 1, further comprising:

selecting a desired temperature of the ablation element;

monitoring a temperature of the ablation element; and

reducing the power to the ablation element when the monitored temperature exceeds the desired temperature.

7. The medical method of claim 1, further comprising:

selecting a maximum limit for the supplied power to the ablation element;

measuring the supplied power to the ablation element;

calculating the average power supplied to the ablation element; and

limiting the average power to the maximum threshold.

8. The medical method of claim 7, further comprising setting a maximum duty cycle equal to the current duty cycle value when the supplied power is at least equal to the maximum limit, and thereafter limiting the duty cycle value to the maximum duty cycle.

9. A medical method, comprising:

advancing an electrode of a medical device into contact with tissue to be treated;

monitoring a temperature of the electrode;

selecting a desired temperature and a threshold variation;

delivering energy to the electrode;

calculating an average temperature of the electrode;

calculating a difference between the electrode temperature and the average electrode temperature;

calculating a continuity value by subtracting the difference from the desired temperature; and

reducing the desired temperature when the continuity value exceeds the threshold variation.

10. The medical method of claim 9, further comprising increasing the desired temperature when the continuity value falls below the threshold variation.

11. The medical method of claim 10, wherein the threshold variation is substantially equal to 5 degrees.

12. The medical method of claim 10, further comprising selecting an increment, and calculating a reduction value by multiplying the continuity value by the increment, wherein reducing the desired temperature is performed by subtracting the reduction value from the desired temperature.

13. The medical method of claim 14, wherein the increment is substantially equal to 1 degree.

14. The medical method of claim 11, wherein the medical device has a plurality of electrodes, and wherein monitoring, delivering, calculating, and reducing are performed individually with respect to each electrode.

15. A medical method, comprising:

advancing an electrode of a medical device into contact with tissue to be treated;

monitoring a temperature of the electrode;

selecting a desired temperature and a threshold value;

delivering energy at a duty cycle value to the electrode;

setting a duty cycle limit equal to an initial duty cycle value;

limiting the energy to a maximum of the duty cycle limit when the threshold value exceeds the temperature.

17. The medical method of claim 17, wherein the threshold value is substantially equal to 50 degrees.

16. The medical method of claim 17, further comprising increasing the duty cycle limit when the temperature exceeds the threshold value.

18. A medical method, comprising:

advancing an electrode of a medical device into contact with tissue to be treated;

selecting a desired maximum power;

delivering energy from a power source at a duty cycle value to the electrode;

monitoring power produced by the power source;

calculating average power produced by the power source;

limiting the average power to the desired maximum power;

setting a maximum duty cycle equal to the current duty cycle value when the power is at least equal to the desired maximum power, and thereafter limiting the duty cycle value to the maximum duty cycle.