Assessment of electrode coupling of tissue ablation

• US 9,271,782 B2
• Filed: 12/06/2006
• Issued: 03/01/2016
• 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, Belhe, Kedar Ravindra, Cao, Hong, Thao, Chou
• Primary Examiner(s): DELLA, JAYMI E
• Application Number:
  US12/095,688
• Publication Number:
  US 20100228247A1
• Time in Patent Office: 3,373 Days
• Field of Search: 600/547, 606/34, 606/38
• US Class Current: 1/1
• 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

an electrical power source at least interconnectable with a first ablation electrode and configured to apply electrical energy to said first ablation electrode;

a data structure having a plurality of empirically predetermined excessive electrical coupling benchmark values corresponding to empirical amounts of electrical energy passing between a testing electrode and a corresponding plurality of types of tissue during ablation that form excessively deep lesions in each of the corresponding plurality of types of tissue, wherein each empirically predetermined excessive electrical coupling benchmark value is related to electrical conductivity and tissue compliance of each of the corresponding plurality of types of tissue, the corresponding plurality of types of tissue including a target tissue;

a coupling assessment module configured to monitor an electrical coupling condition between said first ablation electrode and the target tissue during application of the electrical energy to the target tissue, wherein said coupling assessment module is configured, during application of the electrical energy to said first ablation electrode, to identify development of an elevated electrical coupling condition by comparing at least a portion of an impedance signal measured between said first ablation electrode and the target tissue with one of said plurality of empirically predetermined excessive electrical coupling benchmark values corresponding to the target tissue; and

a display device configured to, upon identification of said development of said elevated electrical coupling condition, generate an output indicative of said elevated electrical coupling condition.

2. The medical system of claim 1, wherein said coupling assessment module is configured to utilize a reactance component of said impedance signal to identify said development of said elevated electrical coupling condition.

3. 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.

4. 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.

5. 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.

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

7. The medical system of claim 6, wherein each of said first ablation electrode and said return electrode are disposable in a common heart chamber.

8. The medical system of claim 6, wherein said return electrode has a larger surface area than said first ablation electrode.