Electrode and associated systems using thermally insulated temperature sensing elements

• US 5,456,682 A
• Filed: 02/02/1994
• Issued: 10/10/1995
• Est. Priority Date: 11/08/1991
• Status: Expired due to Term

• Current Assignee: EP Technology (Boston Scientific Corporation)
• Original Assignee: EP Technology (Boston Scientific Corporation)
• Inventors: Edwards, Stuart D., Stern, Roger A.
• Primary Examiner(s): Pellegrino, Stephen C.
• Assistant Examiner(s): TUCKER, GUY V
• Application Number:
  US08/191,055
• Time in Patent Office: 615 Days
• Field of Search: 606/29, 606/30, 606/31, 606/28, 606/27, 128/736, 128/742, 374/141, 374/152, 364/557, 607/97, 607/100, 607/101, 607/102, 607/154
• US Class Current: 606/31
• 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 18/1206 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 2017/00017 Electrical control of surgical instruments
• CPC Class Codes: A61B 2017/00101 using an array of thermosensors
• CPC Class Codes: A61B 2017/00292 mounted on or guided by flexible, e.g. catheter-like, means
• CPC Class Codes: A61B 2017/003 Steerable
• CPC Class Codes: A61B 2017/00482 with a code
• CPC Class Codes: A61B 2018/00101 low, i.e. thermally insulating
• CPC Class Codes: A61B 2018/00351 Heart
• 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 2018/00684 using lookup tables
• CPC Class Codes: A61B 2018/00702 Power or energy
• CPC Class Codes: A61B 2018/00779 Power or energy
• CPC Class Codes: A61B 2018/00791 Temperature
• CPC Class Codes: A61B 2018/00797 measured by multiple temperature sensors
• CPC Class Codes: A61B 2018/00803 with temperature prediction
• CPC Class Codes: A61B 2018/00815 : measured by a thermistor
• CPC Class Codes: A61B 2018/00827 : Current
• CPC Class Codes: A61B 2018/00869 : Phase
• CPC Class Codes: A61B 2018/00875 : Resistance or impedance
• CPC Class Codes: A61B 2018/00892 : Voltage
• CPC Class Codes: A61B 2018/00916 : with means for switching or controlling the main function of the instrument or device
• CPC Class Codes: A61B 2018/124 : switching the output to different electrodes, e.g. sequentially
• CPC Class Codes: A61B 2018/1253 : monopolar
• CPC Class Codes: A61B 2018/126 : bipolar
• CPC Class Codes: A61B 2090/0803 : Counting the number of times an instrument is used
• CPC Class Codes: A61B 2562/08 : Sensors provided with means for identification, e.g. barcodes or memory chips
• CPC Class Codes: A61M 2205/6018 : providing set-up signals for the apparatus configuration
• CPC Class Codes: A61M 2205/6027 : Electric-conductive bridges closing detection circuits, with or without identifying elements, e.g. resistances, zener-diodes
• CPC Class Codes: A61M 2205/70 : with testing or calibration facilities

Abstract

An ablation electrode carries a temperature sensing element for measuring the temperature of the tissue being ablated. A thermal insulating element associated with the sensing element blocks the transfer of heat energy from between the temperature sensing element and the body. The temperature sensing element therefore measures temperature without being affected by the surrounding thermal mass of the electrode.

Claims

1. A system for supplying radiofrequency energy to ablate endocardial tissue, the system comprising

electrode means for emitting radiofrequency energy, the electrode means including a distal tip end for contacting endocardial tissue for ablating the tissue, the distal tip end including an open cavity, the electrode means being made of a heat conducting material,

temperature sensing means carried within the cavity at the distal tip end of the electrode means, the temperature sensing means including

a sensing tip exposed outside the cavity for contact with the tissue that the distal tip end of the electrode means contacts, the sensing tip being operative for sensing tissue temperature contacting the distal tip end of the electrode means while the electrode means emits radiofrequency energy to ablate the tissue, and

thermal insulating means filling the cavity around the temperature sensing means for blocking the conduction of heat energy from the electrode means and the sensing tip, generating means connected to the electrode means for conducting radiofrequency ablating energy to the electrode means,

control means for the energy generating means including

means for registering the temperature of the endocardial tissue being ablated sensed by the temperature sensing means, and

means for producing a command signal when the tissue temperature sensed by the sensing means deviates from a predetermined temperature condition.

2. An system according to claim 1 wherein the control means includes means for inputting a prescribed temperature condition.

3. An apparatus according to claim 1 wherein the generating means produces radiofrequency ablating energy at different power levels, and

wherein the control means includes means for varying the power level of the generating means in response to the command signal.

4. An apparatus according to claim 3 wherein the command signal increases the power level as the measured tissue temperature decreases toward a prescribed low temperature condition.

5. An apparatus according to claim 3 wherein the command signal decreases the power level as the measured tissue temperature increases toward a prescribed high temperature condition.

6. An apparatus according to claim 3 wherein the command signal interrupts the operation of the generating means.

7. A system for supplying energy to ablate tissue within the heart, the system comprising

an electrode element for contacting tissue while emitting energy to ablate the tissue, the electrode element being made of a heat conducting material,

a temperature sensing element carried in the electrode element, the temperature sensing element including

a sensor having a region for sensing tissue temperature conditions by making thermal conductive contact with tissue, and

thermal insulating material in the electrode element around the temperature sensing element, except for the sensor region, for blocking the thermal conduction of heat energy between the electrode element and the sensor to make the sensor region more responsive to sensed tissue temperature conditions than to the thermal mass of the electrode element,

generating means connected to the electrode element for conducting ablating energy to the electrode element,

control means for the energy generating means including

means for registering the temperature of the tissue contacting the sensor, and

means for producing a command signal when the tissue temperature sensed by the sensor deviates from a predetermined temperature condition.

8. A system according to claim 7 wherein the control means includes means for inputting a prescribed temperature condition.

9. A system according to claim 7 wherein the generating means produces ablating energy at different power levels, and wherein the control means includes means for varying the power level of the generating means in response to the command signal.

10. A system according to claim 9 wherein the command signal increases the power level as the measured tissue temperature decreases toward a prescribed low temperature condition.

11. An apparatus according to claim 9 wherein the command signal decreases the power level as the measured tissue temperature increases toward a prescribed high temperature condition.

12. An apparatus according to claim 7 wherein the command signal interrupts the operation of the generating means.

13. A system for supplying energy to ablate tissue within the heart, the system comprising

an electrode element for contacting tissue while emitting energy to ablate the tissue, the electrode element having a thermal mass,

a temperature sensing element carried in the electrode element, the temperature sensing element including

a sensor having a region for making thermal conductive contact with tissue to sense tissue temperature conditions, and

thermal insulating material in the electrode element between the sensor and the thermal mass of the electrode element, except for the sensor region, for thermally insulating the sensor from the thermal mass of the electrode element to make the sensor region more responsive to sensed tissue temperature conditions than to the thermal mass of the electrode element,

generating means connected to the electrode means for conducting ablating energy to the electrode means,

control means for the energy generating means including

means for registering the temperature sensed by the sensor element, and

means for producing a command signal when the temperature sensed by the sensor element differs from a predetermined temperature condition.

14. A system according to claim 13 wherein the control means includes means for inputting the predetermined temperature condition.

15. A system according to claim 13 wherein the generating means produces ablating energy at different power levels, and wherein the control means includes means for varying the power level of the generating means in response to the command signal.

16. A system according to claim 15 wherein the command signal changes the power level as the temperature sensed by the sensor element approaches a prescribed low temperature condition.

17. A system according to claim 15 wherein the command signal changes the power level as the temperature sensed by the sensor element approaches a prescribed high temperature condition.

18. A system according to claim 13 wherein the command signal interrupts the operation of the generating means.