SENSING CONTACT OF ABLATION CATHETER USING DIFFERENTIAL TEMPERATURE MEASUREMENTS

• US 20110152854A1
• Filed: 12/23/2009
• Published: 06/23/2011
• Est. Priority Date: 12/23/2009
• Status: Active Grant

• Current Assignee: Biosense Webster Incorporated (Johnson & Johnson)
• Original Assignee: Biosense Webster Incorporated (Johnson & Johnson)
• Inventors: Papaioannou, Athanassios, Govari, Assaf, Beeckler, Christopher Thomas
• Granted Patent: US 8,668,686 B2
• Time in Patent Office: Days
• US Class Current: 606/33
• 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 18/20 using laser
• CPC Class Codes: A61B 2017/320069 for ablating tissue
• CPC Class Codes: A61B 2018/00011 with fluids
• CPC Class Codes: A61B 2018/00797 measured by multiple temperature sensors
• CPC Class Codes: A61B 2018/00821 measured by a thermocouple

Abstract

Tissue ablation is carried out using insertion tube having at least one ablation electrode, a first temperature sensor disposed on the distal portion sufficiently proximate the ablation electrode to detect heat generated during the ablation procedure, a second temperature sensor disposed on the distal portion sufficiently distant from the ablation electrode to be unable to detect the heat, and electronic logic circuitry linked to the first temperature sensor and the second temperature sensor and programmed to compute a temperature differential between respective temperatures sensed by the first temperature sensor and the second temperature sensor when conveying the electromagnetic energy. Satisfactory contact status between the ablation electrode and the target tissue is indicated when the temperature differential exceeds a predetermined threshold.

Claims

1. A medical apparatus, comprising:

an insertion tube having a distal portion;

at least one ablation electrode disposed on the distal portion for conveying electromagnetic energy to a target tissue during an ablation procedure;

a first temperature sensor disposed on the distal portion sufficiently proximate the ablation electrode to detect heat generated in the target tissue during the ablation procedure;

a second temperature sensor disposed on the distal portion sufficiently spaced apart from the ablation electrode to be relatively less responsive to the heat than the first temperature sensor; and

electronic logic circuitry linked to the first temperature sensor and the second temperature sensor and programmed to compute a temperature differential between respective temperatures sensed by the first temperature sensor and the second temperature sensor when conveying the electromagnetic energy, and to indicate a satisfactory contact status between the ablation electrode and the target tissue when the temperature differential exceeds a predetermined threshold.

2. The apparatus according to claim 1, wherein the electronic logic circuitry is programmed to indicate an unsatisfactory contact status between the ablation electrode and the target tissue when the temperature differential fails to exceed the predetermined threshold.

3. The apparatus according to claim 1, wherein the first temperature sensor is in contact with the target tissue when the ablation electrode contacts the target tissue.

4. The apparatus according to claim 1, wherein the insertion tube is a lasso catheter.

5. The apparatus according to claim 1, wherein the electronic logic circuitry is programmed to compute a first temperature differential and a second temperature differential when relatively high and low flows of coolant are applied to the ablation electrode, respectively, wherein the electronic logic circuitry is programmed to indicate an unsatisfactory contact status between the ablation electrode and the target tissue when a difference between the first temperature differential and the second temperature differential fails to exceed the predetermined threshold.

6. The apparatus according to claim 1, wherein the first temperature sensor and the second temperature sensor are thermocouples.

7. The apparatus according to claim 1, further comprising an ablation power generator coupled to the ablation electrode to supply the energy thereto.

8. The apparatus according to claim 1, wherein the insertion tube is configured for insertion through a blood vessel into a heart of a subject for ablation of myocardial tissue in the heart.

9. The apparatus according to claim 1, wherein the first temperature sensor is sufficiently spaced apart from the second temperature sensor to cause the temperature differential to be at least 2 degrees C. when during the ablation procedure.

10. The apparatus according to claim 1, wherein the insertion tube has accessory ports bored therethrough for delivery of coolant to an ablation site comprising the target tissue.

11. A method for treatment, comprising:

bringing a probe into contact with a target tissue in a body of a subject, the probe having first and second temperature sensors on a distal portion of the probe and an ablation electrode thereon, the first and second temperature sensors being disposed on the distal portion, the second temperature sensor being spaced apart from the first temperature sensor such that when the ablation electrode is operationally engaged with the target tissue, the second temperature sensor is less responsive to heat generated at an ablation site comprising the target tissue than the first temperature sensor;

applying energy through the ablation electrode to ablate the target tissue in the body;

reading the first and second temperature sensors in order to compute a temperature difference therebetween; and

determining the contact to be sufficient for the treatment if the temperature difference is greater than a predetermined threshold.

12. The method according to claim 11, wherein the probe is a lasso catheter.

13. The method according to claim 11, wherein computing the temperature difference comprises computing a first temperature differential and a second temperature differential when relatively high and low flows of coolant are applied to the ablation electrode, respectively;

further comprising indicating an unsatisfactory contact status between the ablation electrode and the target tissue when a difference between the first temperature differential and the second temperature differential fails to exceed the predetermined threshold.

14. The method according to claim 11, wherein the first temperature sensor and the second temperature sensor are thermocouples.

15. The method according to claim 11, further comprising discontinuing applying energy when the temperature difference fails to exceed the predetermined threshold.

16. The method according to claim 11, wherein the probe is configured for insertion through a blood vessel into a heart of the subject for ablation of myocardial tissue in the heart.