SYSTEM AND METHOD FOR ASSESSING COUPLING BETWEEN AN ELECTRODE AND TISSUE

• US 20100168735A1
• Filed: 12/30/2009
• Published: 07/01/2010
• 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: Hill, Lewis C., Malinin, Yuriy, Deno, Don Curtis, Miller, Stephan P., Sih, Haris
• Granted Patent: US 8,406,866 B2
• Time in Patent Office: Days
• US Class Current: 606/34
• CPC Class Codes: A61B 18/00 Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body eye surgery A61F9/007; ear surgery A61F11/00
• CPC Class Codes: A61B 18/1233 with circuits for assuring patient safety
• 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 2018/00178 Electrical connectors
• CPC Class Codes: A61B 2018/00642 with feedback, i.e. closed loop control
• CPC Class Codes: A61B 2018/00773 Sensed parameters
• CPC Class Codes: A61B 2018/00875 Resistance or impedance
• CPC Class Codes: A61B 2090/065 for measuring contact or contact pressure
• CPC Class Codes: A61B 5/053 Measuring electrical impedance or conductance of a portion of the body
• CPC Class Codes: A61B 5/6885 Monitoring or controlling sensor contact pressure
• CPC Class Codes: A61B 5/6886 Monitoring or controlling distance between sensor and tissue

Abstract

A system and method for assessing a degree of coupling between an electrode and tissue in a body is provided. Values for first and second components of a complex impedance (e.g., resistance and reactance or impedance magnitude and phase angle) between the electrode and the tissue are obtained. These values are used together with a standardization value indicative of a deviation from a reference standard by a parameter associated with at least one of the body, the electrode and another component of the system to calculate a coupling index that is indicative of a degree of coupling between the electrode and the tissue. The coupling index may be displayed to a clinician in a variety of ways to indicate the degree of coupling to the clinician. The system and method find particular application in ablation of tissue by permitting a clinician to create lesions in the tissue more effectively and safely.

Claims

1. A system for assessing a degree of coupling between an electrode and a tissue in a body, comprising:

an electronic control unit configured to acquire values for first and second components of a complex impedance between said electrode and said tissue and to calculate a coupling index responsive to said values and a standardization value indicative of a deviation from a reference standard by a parameter associated with at least one of said body, said electrode and another component of said system, said coupling index indicative of a degree of coupling between said electrode and said tissue.

2. The system of claim 1 wherein said first and second components comprise a resistance between said electrode and said tissue and a reactance between said electrode and said tissue.

3. The system of claim 1 wherein said first and second components comprise an impedance magnitude between said electrode and said tissue and an impedance phase angle.

4. The system of claim 1 wherein said coupling comprises an electrical coupling.

5. The system of claim 1 wherein said electronic control unit applies said standardization value as an offset to said values of said first and second components of said complex impedance.

6. The system of claim 1 wherein said electronic control unit applies said standardization value as a scaling of at least one of said values of said first and second components of said complex impedance.

7. The system of claim 1 wherein said electronic control unit acquires said standardization value from a memory of said component.

8. The system of claim 1 wherein said electronic control unit acquires said standardization value responsive to a value contained in a memory of said component.

9. The system of claim 1 wherein said electronic control unit is further configured to determine said standardization value responsive to a comparison between a baseline coupling index obtained when said electrode is not in contact with said tissue and a reference coupling index.

10. An article of manufacture, comprising:

a computer storage medium having a computer program encoded thereon for determining a degree of coupling between an electrode and tissue in a body, said computer program including code for;

calculating a coupling index responsive to values for first and second components of a complex impedance between said electrode and said tissue and a standardization value indicative of a deviation from a reference standard by a parameter associated with at least one of said body, said electrode and another component of a system controlling said electrode, said coupling index indicative of a degree of coupling between said electrode and said tissue.

11. The article of manufacture of claim 10 wherein said first and second components comprise a resistance between said electrode and said tissue and a reactance between said electrode and said tissue.

12. The article of manufacture of claim 10 wherein said first and second components comprise an impedance magnitude between said electrode and said tissue and an impedance phase angle.

13. The article of manufacture of claim 10 wherein said coupling comprises an electrical coupling.

14. The article of manufacture of claim 10 wherein said code for calculating a coupling index applies said standardization value as an offset to said values of said first and second components of said complex impedance.

15. The article of manufacture of claim 10 wherein said code for calculating a coupling index applies said standardization value as a scaling of at least one of said values of said first and second components of said complex impedance.

16. The article of manufacture of claim 10 wherein said code for calculating a coupling index includes code for determining said standardization value responsive to a comparison between a baseline coupling index obtained when said electrode is not in contact with said tissue and a reference coupling index.

17. The article of manufacture of claim 10, further comprising a catheter to which said electrode is coupled.

18. A method for assessing a degree of coupling between an electrode and a tissue in a body, comprising the steps of:

acquiring values for first and second components of a complex impedance between said electrode and said tissue; and

,

calculating a coupling index responsive to said values and a standardization value indicative of a deviation from a reference standard by a parameter associated with at least one of said body, said electrode and another component of a system controlling said electrode, said coupling index indicative of a degree of coupling between said electrode and said tissue.

19. The method of claim 18 wherein said first and second components comprise a resistance between said electrode and said tissue and a reactance between said electrode and said tissue.

20. The method of claim 18 wherein said first and second components comprise an impedance magnitude between said electrode and said tissue and an impedance phase angle.

21. The device of claim 18, further comprising the steps of:

applying an excitation signal between said electrode and a first reference electrode;

measuring a voltage between said electrode and a second reference electrode;

wherein said values for said first and second components are acquired responsive to said voltage.