Assessment of electrode coupling for tissue ablation

• US 20100298823A1
• Filed: 12/06/2006
• Published: 11/25/2010
• 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
• Granted Patent: US 8,317,783 B2
• Time in Patent Office: Days
• US Class Current: 606/34
• 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 2018/00363 Epicardium
• CPC Class Codes: A61B 2018/00869 Phase
• CPC Class Codes: A61B 2018/00898 Alarms or notifications created in response to an abnormal condition

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

an electrode;

a first electrical power source configured to provide a first current to said electrode for executing a first medical procedure; and

a first electrode coupling assessment module, wherein said first electrode coupling assessment module is configured to assess a coupling between said electrode and a target tissue associated with said first medical procedure, and wherein said first electrode coupling assessment module uses said first current to assess said coupling.

2. The medical system of claim 1, wherein said first medical procedure is tissue ablation within a heart.

3. The medical system of claim 1, wherein said coupling is selected from the group consisting of mechanical coupling and electrical coupling.

4. The medical system of claim 1, wherein said first electrode coupling assessment module comprises a phase comparator.

5. The medical system of claim 4, wherein said first electrode coupling assessment module further comprises a first data structure, that in turn comprises at least one phase angle benchmark value.

6. The medical system of claim 4, wherein said system further comprises an operator input device, said operator input device being configured to accept an operator input when said electrode is located in a desired medium, said operator input being operative to indicate an establishment of a baseline coupling condition.

7. The medical system of claim 6, wherein said first electrode coupling assessment module further comprises a first data structure, and wherein an operation of said operator input device zeroes at least one phase angle benchmark value.

8. The medical system of claim 4, wherein said first electrode coupling assessment module further comprises wherein a data structure, that in turn comprises first, second, and third ranges, wherein said first range comprises phase angles associated with an insufficient coupling condition, wherein said second range comprises phase angles associated with a sufficient coupling condition, and wherein said third range comprises phase angles associated with an elevated coupling condition.

9. The medical system of claim 1, wherein said first electrode coupling assessment module comprises a reactance comparator.

10. The medical system of claim 9, wherein said first electrode coupling assessment module further comprises a first data structure, that in turn comprises at least one reactance benchmark value.

11. The medical system of claim 9, wherein said first electrode coupling assessment module further comprises a data structure, that in turn comprises first, second, and third ranges, wherein said first range comprises reactances associated with an insufficient coupling condition, wherein said second range comprises reactances associated with a sufficient coupling condition, and wherein said third range comprises reactances associated with an elevated coupling condition.

12. The medical system of claim 1, further comprising:

a second electrical power source configured to provide a second current to said electrode for executing an electrode coupling assessment operation;

a switch operable to interconnect said electrode with said first electrical power source in a first switch position, and operable to interconnect said electrode with said second electrical power source in a second switch position; and

a second electrode coupling assessment module, wherein said second electrode coupling assessment module is configured to assess a coupling between said electrode and said target tissue, and wherein said second electrode coupling assessment module uses said second current.

13. The medical system of claim 12, wherein said second current is of a different magnitude than said first current, and wherein a frequency of electrical signals provided by said first and second electrical power sources at said first and second currents, respectively, are at least substantially equal.

14. The medical system of claim 12, wherein said first and second electrode coupling assessment modules are of an identical configuration.

15. The medical system of claim 12, wherein said first electrode coupling assessment module is available for assessing said coupling during said first medical procedure, and wherein said second electrode coupling assessment module is available for assessing said coupling only other than during execution of said first medical procedure.

16. 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, wherein a first current is associated with said first electrical signal;

executing a first medical procedure using said sending step; and

assessing a coupling between said electrode and said tissue using said sending a first electrical signal step.

17. The method of claim 16, wherein said first medical procedure is ablating heart tissue.

18. The method of claim 16, wherein said coupling is selected from the group consisting of mechanical coupling and electrical coupling.

19. The method of claim 16, wherein said assessing step comprises comparing a phase angle to at least one phase angle benchmark value.

20. The method of claim 16, wherein said assessing step comprises comparing a phase angle to a data structure, that in turn comprises first, second, and third ranges, wherein said first range comprises phase angles associated with an insufficient coupling condition, wherein said second range comprises phase angles associated with a sufficient coupling condition, and wherein said third range comprises phase angles associated with an elevated coupling condition.

21. The method of claim 16, wherein said assessing step comprises comparing a reactance to at least one reactance benchmark value.

22. The method of claim 16, wherein said assessing step comprises comparing a reactance to a data structure, that in turn comprises first, second, and third ranges, wherein said first range comprises reactances associated with an insufficient coupling condition, wherein said second range comprises reactances associated with a sufficient coupling condition, and wherein said third range comprises reactances associated with an elevated coupling condition.

23. The method of claim 16, further comprising the steps of:

sending a second electrical signal to said electrode, wherein a second current is associated with said second electrical signal; and

assessing said coupling between said electrode and said tissue using said sending a second electrical signal step.

24. The method of claim 23, wherein said second current is of a different magnitude than said first current, and wherein a frequency of said first and second electrical signals are at least substantially equal.

25. The method of claim 24, where said first electrical signal is issued from a first electrical power source, wherein said second electrical signal is issued from a second electrical power source, and wherein said assessing step comprises switching between said first and second electrical power sources.

26. The method of claim 25, wherein said assessing step uses said second electrical signal when said switching step has interconnected said electrode with said second electrical power source in preparation for said executing a first medical procedure step, and wherein said assessing step uses said first electrical signal after said switching step has interconnected said electrode with said first electrical power source for said executing a first medical procedure step.