Assessment of electrode coupling for tissue ablation

• US 9,283,026 B2
• Filed: 12/06/2006
• Issued: 03/15/2016
• Est. Priority Date: 12/06/2005
• Status: Active Grant

• Current Assignee: St. Jude Medical (Abbott Laboratories Incorporated)
• Original Assignee: St. Jude Medical (Abbott Laboratories Incorporated)
• Inventors: Paul, Saurav, Cao, Hong, Belhe, Kedar Ravindra
• Primary Examiner(s): DELLA, JAYMI E
• Application Number:
  US12/096,070
• Publication Number:
  US 20080300589A1
• Time in Patent Office: 3,387 Days
• Field of Search: 600/547, 606 34- 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 (14) and a method for assessing electrode-tissue contact and coupling are disclosed. An exemplary electrode catheter (14) comprises an electrode (20) adapted to apply electrical energy. A measurement circuit (42) is adapted to measure impedance between the electrode (20) and ground as the electrode approaches a target tissue (24). A processor (50) determines a contact and coupling condition for the target tissue (24) based at least in part on reactance of the impedance measured by the measurement circuit (42). In another exemplary embodiment, the electrode catheter (14) determines the contact and coupling condition based at least in part on a phase angle of the impedance.

Claims

1. A coupling sensing system comprising:

a measurement circuit adapted to measure impedance between an electrode of a catheter adapted to apply electrical energy and ground as the electrode approaches a target tissue;

a first data structure including a plurality of sets of empirically predetermined electrical coupling conditions indicative of empirical amounts of ablative energy passing between a testing electrode and a corresponding plurality of types of tissue during ablation, wherein each set of said plurality of sets of empirically predetermined electrical coupling conditions is related to electrical conductivity and mechanical compliance of each type of tissue of the corresponding plurality of types of tissue, the corresponding plurality of types of tissue including the target tissue; and

a processor configured to make a determination of an electrical coupling condition indicative of an amount of ablative energy that will pass between said electrode and the target tissue upon application of electrical ablation energy to said electrode, wherein said determination is based at least in part on a difference between the impedance measured by said measurement circuit and a baseline value in blood proximate to the target tissue, and wherein said processor is configured to make a comparison of said difference with one set of said plurality of sets of empirically predetermined electrical coupling conditions corresponding to the target tissue; and

an output device for indicating the electrical coupling condition to a user prior to application of said ablation energy to said electrode.

2. The coupling sensing system of claim 1, wherein a level of said electrical coupling condition directly corresponds to a reactance component of the impedance measured.

3. The coupling sensing system of claim 1, wherein a level of said electrical coupling condition directly corresponds to a phase angle component of the impedance measured.

4. The coupling sensing system of claim 1, wherein the output device includes analog output corresponding to the electrical coupling condition.

5. The coupling sensing system of claim 1, wherein the measurement circuit includes a resistance-capacitance-inductance (RCL) meter.

6. The coupling sensing system of claim 1, wherein the measurement circuit includes a phase detection circuit.

7. The coupling sensing system of claim 1, wherein the electrode is adapted to apply said electrical energy at a first power for the determination of the electrical coupling condition and apply said electrical energy at a second power, wherein said electrical energy at said second power is said ablation energy.

8. The coupling sensing system of claim 7, further comprising a constant current source to apply said electrical energy for said electrical coupling condition.

9. The coupling sensing system of claim 1, wherein each of said plurality of sets of empirically predetermined electrical coupling conditions further comprises:

a plurality of electrical coupling conditions corresponding to a plurality of measurement frequencies.