Assessment of electrode coupling of tissue ablation

• US 20100228247A1
• Filed: 12/06/2006
• Published: 09/09/2010
• Est. Priority Date: 12/06/2005
• Status: Active Grant

• Current Assignee: St. Jude Medical, Atrial Fibrillation Division, Inc. (Abbott Laboratories)
• Original Assignee: St. Jude Medical, Atrial Fibrillation Division, Inc. (Abbott Laboratories)
• Inventors: Paul, Saurav, Cao, Hong, Belhe, Kedar Ravindra, Thao, Chou
• Granted Patent: US 9,271,782 B2
• Time in Patent Office: Days
• US Class Current: 606/41
• CPC Class Codes: A61B 18/1206 Generators 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 2018/00303 active, e.g. with a motor creating vibrations
• CPC Class Codes: A61B 2018/00357 Endocardium
• CPC Class Codes: A61B 2018/00577 Ablation
• CPC Class Codes: A61B 2018/00642 with feedback, i.e. closed loop control
• CPC Class Codes: A61B 2018/00666 using a threshold value
• CPC Class Codes: A61B 2018/00702 Power or energy
• CPC Class Codes: A61B 2018/0075 Phase
• CPC Class Codes: A61B 2018/00755 Resistance or impedance
• CPC Class Codes: A61B 2018/00869 Phase
• CPC Class Codes: A61B 2018/00875 Resistance or impedance
• 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: A61B 5/053 Measuring electrical impedance or conductance of a portion of the body

Abstract

An electrode catheter and a method for assessing electrode-tissue contact and coupling are disclosed. An exemplary electrode catheter comprises an electrode adapted to apply electrical energy. A measurement circuit is adapted to measure impedance between the electrode and ground as the electrode approaches a target tissue. A processor determines a contact and coupling condition for the target tissue based at least in part on reactance of the impedance measured by the measurement circuit. In another exemplary embodiment, the electrode catheter determines the contact and coupling condition based at least in part on a phase angle of the impedance.

Claims

1. A medical system comprising

a first electrode;

an electrical power source at least interconnectable with said first electrode;

a coupling assessment module configured to identify an elevated coupling condition between said first electrode and tissue.

2. The medical system of claim 1, wherein said coupling assessment module is configured to compare a reactance to at least one reactance benchmark value to identify said elevated coupling condition.

3. The medical system of claim 1, wherein said elevated coupling condition exists when a reactance is less than a predetermined negative reactance value.

4. The medical system of claim 1, wherein said coupling assessment module is configured to compare a phase angle to at least one phase angle benchmark value to identify said elevated coupling condition.

5. The medical system of claim 1, wherein said elevated coupling condition exists when a phase angle is less than a predetermined negative phase angle value.

6. The medical system of claim 1, wherein said coupling assessment module is configured to compare a frequency, at which phase angle has a preset value, to at least one benchmark frequency value to identify said elevated coupling condition.

7. The medical system of claim 1, wherein said elevated coupling condition exists when a frequency, at which phase angle has a preset value, is greater than a predetermined frequency value.

8. The medical system of claim 1, wherein said coupling assessment module is configured to compare a frequency, at which reactance has a preset value, to at least one benchmark frequency value to identify said elevated coupling condition.

9. The medical system of claim 1, wherein said elevated coupling condition exists when a frequency, at which reactance has a preset value, is greater than a predetermined frequency value.

10. The medical system of claim 1, further comprising an elevated coupling condition indicator operatively interconnected with said coupling assessment module.

11. The medical system of claim 1, further comprising a return electrode, wherein said first and return electrodes are associated with different catheters.

12. The medical system of claim 11, wherein each of said first and return electrodes are disposable in a common heart chamber.

13. The medical system of claim 11, wherein said return electrode has a larger surface area than said first electrode.

14. A method for performing a medical procedure, the method comprising the steps of:

positioning an electrode relative to a target tissue;

sending a first electrical signal to said electrode;

identifying an elevated coupling condition between said electrode and said target tissue using said sending a first electrical signal step.

15. The method of claim 14, wherein said identifying step comprises comparing a reactance to at least one reactance benchmark value.

16. The method of claim 14, wherein said identifying step comprises determining if a reactance is less than a predetermined negative reactance value.

17. The method of claim 14, wherein said identifying step comprises comparing a phase angle to at least one phase angle benchmark value.

18. The method of claim 14, wherein said identifying step comprises determining if a phase angle is less than a predetermined negative phase angle value.

19. The method of claim 14, wherein said identifying step comprises comparing a frequency, at which phase angle has a preset value, with at least one benchmark frequency value.

20. The method of claim 14, wherein said identifying step comprises determining if a frequency, at which phase angle has a preset value, is greater than a predetermined frequency value.

21. The method of claim 14, wherein said identifying step comprises comparing a frequency, at which reactance has a preset value, to at least one frequency benchmark value.

22. The method of claim 14, wherein said identifying step comprises determining if a frequency, at which reactance has a preset value, is greater than a predetermined frequency value.