Ablation Catheter With Sensor Array And Discrimination Circuit To Minimize Variation In Power Density

• US 20080161788A1
• Filed: 12/28/2006
• Published: 07/03/2008
• Est. Priority Date: 12/28/2006
• Status: Active Grant

• Current Assignee: Jeremy D. Dando, Timothy G. Curran, Todd R. Stangenes
• Original Assignee: St. Jude Medical (Abbott Laboratories Incorporated)
• Inventors: Dando, Jeremy D., Stangenes, Todd R., Curran, Timothy G.
• Granted Patent: US 7,766,907 B2
• Time in Patent Office: Days
• US Class Current: 606/34
• 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 2018/00642 with feedback, i.e. closed loop control
• CPC Class Codes: A61B 2018/00797 measured by multiple temperature sensors
• CPC Class Codes: A61B 2018/00839 Bioelectrical parameters, e.g. ECG, EEG
• CPC Class Codes: A61B 2018/1472 for use with liquid electrolyte, e.g. virtual electrodes

Abstract

A catheter is designed with a virtual electrode structure for creating a linear lesion. The catheter includes a sensor array that measures temperatures of adjacent tissue along the length of the virtual electrode section. The sensors in the sensor array include a conductive material that is substantially coated with an electrically and thermally insulating material. An aperture is formed in the insulating coating to expose an area of the conductive material. Leads are coupled with each sensor and are connected at their opposite, proximal ends with a discrimination circuit. The circuit processes the signals induced in the sensors to output a single temperature measurement, for example, the highest temperature, the lowest temperature, or the average temperature. The sensors also measure cardiac electrical activity and the leads are further connected to an electrocardiograph monitor to determine the efficacy of treatment.

Claims

1. A catheter comprising

an elongate shaft defining a fluid lumen;

a proximal section;

a virtual electrode ablation section at a distal end of the elongate shaft in fluid communication with the fluid lumen;

a plurality of sensors positioned along the virtual electrode ablation section of the elongate shaft, and wherein each of the plurality of sensors further comprises

an electrically conductive material; and

an insulating coating substantially covering the electrically conductive material; and

a plurality of sensor leads extending from the proximal section to the virtual electrode ablation section, wherein each of the plurality of sensor leads is coupled with a respective one of the plurality of sensors.

2. The catheter of claim 1, wherein the insulating coating defines a sensing aperture that exposes an area of the electrically conductive material.

3. The catheter of claim 2, wherein each of the plurality of sensors is a ring that encircles the catheter.

4. The catheter of claim 2, wherein the sensing apertures of each of the plurality of sensors are arranged longitudinally along the virtual electrode ablation section of the catheter in a linear array.

5. The catheter of claim 2, wherein the virtual electrode ablation section includes

a plurality of ports defined within an exterior wall of the elongate shaft and in fluid communication with the fluid lumen, wherein the plurality of ports is arranged longitudinally along the elongate shaft in a linear array;

and

an electrode positioned within the fluid lumen.

6. The catheter of claim 5, wherein each of the plurality of sensors forms a ring that encircles the elongate shaft and wherein the sensing apertures of each of the plurality of sensors are arranged longitudinally along the virtual electrode ablation section of the elongate shaft in a linear array.

7. The catheter of claim 6, wherein the linear array of the sensing apertures is collinear with the linear array of the plurality of ports.

8. The catheter of claim 6, wherein at least one of the plurality of sensors is positioned between a pair of the plurality of ports.

9. The catheter of claim 6, wherein at least one of the plurality of ports is positioned between a pair of the plurality of sensors.

10. The catheter of claim 1, wherein each of the plurality of sensors measures temperature.

11. The catheter of claim 1, wherein each of the plurality of sensors measures cardiac electrical signals.

12. The catheter of claim 1, wherein each of the sensors comprises a thermistor.

13. The catheter of claim 1, wherein each of the plurality of sensor leads comprises a thermocouple.

14. The catheter of claim 2, wherein each of the plurality of sensor leads couples with the electrically conductive material of a respective one of plurality of sensors at a point adjoining the respective sensing aperture.

15. A circuit for discriminating between a plurality of temperature measurements generated by an array of sensors positioned on an ablation catheter, the circuit comprising:

an input signal receiving component for receiving a plurality of input signals from individual sensors in the sensor array corresponding to the plurality of temperature measurements;

a plurality of amplifier components, each having a first input, a second input, and an output, wherein said first input of each amplifier component is coupled with said input signal receiving component for receiving a respective one of the plurality of input signals;

a plurality of rectifier components, each having a first terminal and a second terminal;

wherein said first terminal of each rectifier component is coupled with said output of a respective one of said plurality of amplifier components;

a feedback loop coupled with said second terminal of each of said plurality of rectifier components and further coupled with said second input of each of said plurality of amplifier components;

wherein the voltage level of said feedback loop substantially follows a voltage received atone of said plurality of said input signal receiving components; and

an output component coupled with said feedback loop for providing an output signal corresponding to said voltage level of said feedback loop.

16. The circuit of claim 15, wherein an output buffer component is interposed between said feedback loop and said output component.

17. The circuit of claim 15, wherein said input signal receiving component receives the plurality of input signals from an array of thermocouple sensors.

18. The circuit of claim 15, wherein said input signal receiving component receives the plurality of input signals from an array of thermistor sensors.

19. The circuit of claim 15, further comprising a plurality of signal buffer components interposed between the input signal receiving component and the plurality of amplifier components, wherein each signal buffer component is coupled with the first input of a respective one of the amplifier components.

20. The circuit of claim 15, wherein the circuit further comprises a plurality of output leads coupled with the signal receiving component for providing each of the plurality of input signals to an electrocardiograph.

21. The circuit of claim 15, wherein the voltage received at said one of said plurality of said input receiving components corresponds to a high temperature measurement of the plurality of temperature measurements represented by the plurality of input signals.

22. The circuit of claim 15, wherein the voltage received at said one of said plurality of said input receiving components corresponds to a low temperature measurement of the plurality of temperature measurements represented by the plurality of input signals.

23. A system for discriminating between a plurality of temperature measurements during the performance of a cardiac ablation procedure, the system comprising

a catheter comprising

an elongate shaft defining a fluid lumen;

a proximal section;

a virtual electrode ablation section at a distal end of the elongate shaft in fluid communication with the fluid lumen;

an electrode lead extending through the proximal section to distal end and electrically exposed within the fluid lumen in the virtual electrode ablation section;

a plurality of sensors positioned along the virtual electrode ablation section of the elongate shaft, and wherein each of the plurality of sensors further comprises

a conductive material; and

an insulating coating substantially covering the conductive material, wherein the insulating coating defines a sensing aperture that exposes an area of the conductive material; and

a plurality of sensor leads extending from the virtual electrode ablation section to the proximal section, wherein each of the plurality of sensor leads is coupled with a respective one of the plurality of sensors;

a circuit comprising

an input signal receiving component for receiving a plurality of input signals from individual sensors in the sensor array corresponding to the plurality of temperature measurements;

a plurality of amplifier components, each having a first input, a second input, and an output, wherein said first input of each amplifier component is coupled with said input signal receiving component for receiving a respective one of the plurality of input signals;

a plurality of rectifier components, each having a first terminal and a second terminal;

wherein said first terminal of each rectifier component is coupled with said output of a respective one of said plurality of amplifier components;

a feedback loop coupled with said second terminal of each of said plurality of rectifier components and further coupled with said second input of each of said plurality of amplifier components;

wherein the voltage level of said feedback loop substantially follows a voltage received atone of said plurality of said input signal receiving components; and

an energy source comprising

an input electrically coupled with the output component of the circuit; and

an output electrically coupled with the electrode lead.

24. The system of claim 23, wherein the energy source is a radio frequency power generator.

25. The system of claim 23, wherein the virtual electrode ablation section further comprises

a plurality of ports defined within an exterior wall of the elongate shaft and in fluid communication with the fluid lumen;

wherein the plurality of ports is arranged longitudinally along the elongate shaft in a linear array;

wherein each of the plurality of sensors forms a ring that encircles the elongate shaft;

wherein the sensing apertures of each of the plurality of sensors are arranged longitudinally along the virtual electrode ablation section of the elongate shaft in a linear array;

wherein the liner array of the sensing apertures is collinear with the linear array of the plurality of ports; and

wherein each of the plurality of ports is positioned between a pair of the plurality of sensors.

26. A sensor for use in conjunction with a cardiac ablation catheter, the sensor comprising

a conductive band encircling an outer surface of the catheter;

an insulating coating substantially covering an outer surface of the conductive band,

wherein the insulating coating defines a sensing aperture exposing a portion of the conductive band; and

at least one lead wire electrically coupled with the conductive band.

27. The catheter of claim 26, wherein the at least one lead wire couples with the conductive band at a point adjoining the sensing aperture.

28. The sensor of claim 26, wherein the conductive band comprises a conductive material selected from the group consisting of platinum, platinum-indium, platinum-tungsten, gold, and stainless steel.

29. The sensor of claim 26, wherein the conductive band is thermally conductive.

30. The sensor of claim 26, wherein the insulating coating comprises a material selected from the following:

polyester, polyamide, and polyimide.

31. The sensor of claim 26, wherein the sensor measures both temperature and cardiac electrical signals.

32. The sensor of claim 26, further comprising a thermocouple.

33. The sensor of claim 26, further comprising a thermistor.

34. The sensor of claim 26, wherein the at least one lead wire comprises a thermocouple.