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1. (WO1991016859) TEMPERATURE CONTROLLED RF COAGULATION
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Claims - 1. A radiofrequency medical device for ohmic heating of tissue of a patient in order to induce coagulation, comprising a plurality of patient-contacting RF conductors between which RF current of a frequency in the range of about 100 kilohertz to 100 megahertz flows for tissue-coagulation, at least one of said conductors being a thermally conductive electrode that concentrates RF current in a local region of the patient's tissue contacted by said electrode, means to connect said electrode to one pole of an RF power supply, means to connect a second pole of said RF power supply to the patient via a second said conductor, a temperature sensor carried by and in thermally conductive relationship with said thermally conductive electrode, said temperature sensor being constructed and arranged to sense the temperature of said electrode, and thereby to sense indirectly the temperature of tissue contacted by the electrode, said temperature sensor having a greater accuracy in the absence of interfering RF electrical noise caused by said RF current passing through said thermally conductive electrode than in the presence of said interfering RF electrical noise, feedback means
connecting said sensor to a control circuit, said control circuit being constructed to modulate RF power applied to said electrode according to the signal received from said
temperature sensor, said control circuit and RF power supply constructed to alternate between two operating modes, in the first mode said RF power supply applying RF power to said electrode, in the second mode said control circuit sensing a signal from said temperature sensor in the absence of RF signal, said control circuit constructed to compare the signal from said temperature sensor to a set value and to modulate the RF power applied to said electrode in accordance with said set value.
2. The RF medical device of claim 1 wherein said temperature sensor is a thermistor.
3. The RF medical device of claim 1 wherein the period of temperature sensing is of the order of 1 percent of the cycle time.
4. The RF medical device of' claim 1 wherein said set value is a user set reference signal internal to said control circuit, and said control circuit is constructed and arranged to modulate RF power applied to said electrode to cause said temperature of said temperature sensor to approach a temperature represented by said reference signal, thereby to control the temperature of said electrode and consequently the temperature of tissue contacted by the electrode.
5. The RF medical device of claim 1 wherein said second conductor is a patient grounding plate.
6. The RF medical device of claim 1 wherein said conductors comprise opposed electrodes each of which has a localized contact with the tissue of a patient.
7. The RF medical device of claim 6 wherein said electrodes are mounted on opposing jaws of a forceps.
8. The RF medical device of claim 6 or 7 wherein each of said electrodes is contacted by a said temperature sensor monitored by said control circuit.
9. The RF medical device of claim 8 wherein said RF voltage is modulated in accordance with the higher temperature that is sensed by a respective sensor.
10. The RF medical device of claim 1 wherein said temperature sensor comprises a thermocouple.
11. A radiofrequency medical device for ohmic heating of tissue of a patient in order to induce coagulation, comprising a hemostasis probe constructed for gastro-intestinal hemostasis, a plurality of patient-contacting RF conductors between which RF current of a frequency in the range of about 100 kilohertz to 100 megahertz flows for tissue-coagulation, at least one of said conductors being a thermally conductive electrode, mounted on said gastro-intestinal hemostasis probe, that concentrates RF current in a local region of the patient's tissue contacted by said
electrode, means to connect said electrode to one pole of an RF power supply, means to connect a second pole of said RF power supply to the patient via a second said conductor, a temperature sensor carried by and in- thermally conductive relationship with said thermally conductive electrode, said temperature sensor being constructed and arranged to sense the temperature of said electrode, and thereby to sense indirectly the temperature of tissue contacted by the electrode, said temperature sensor having a greater accuracy in the absence of interfering RF electrical noise caused by said RF current passing through said thermally conductive electrode than in the presence of said interfering RF electrical noise, feedback means connecting said sensor to a control circuit, said control circuit being constructed to modulate RF power applied to said electrode according to the signal received from said temperature sensor, said control circuit and RF power supply constructed to alternate between two operating modes, in the first mode said RF power supply applying RF power to said electrode, in the second mode said control circuit sensing a signal from said temperature sensor in the absence of RF signal, said control circuit constructed to compare the signal from said temperature sensor to a set value and to modulate the RF power applied to said electrode in accordance with said set value.
12. A radiofrequency medical device for ohmic heating of tissue of a patient in order to induce coagulation, comprising a surgical hemostasis probe, a plurality of
patient-contacting RF conductors between which RF current of a frequency in the range of about 100 kilohertz to 100 megahertz flows for tissue-coagulation, at least one of said conductors being a thermally conductive electrode, located on said surgical hemostasis probe, that concentrates RF current in a local region the patient's of tissue contacted by said
electrode, means to connect said electrode to one pole of an RF power supply, means to connect a second pole of said RF power supply to the patient via a second said conductor, a temperature sensor carried by and in thermally conductive relationship with said thermally conductive electrode, said temperature sensor being constructed and arranged to sense the temperature of said electrode, and thereby to sense indirectly the temperature of tissue contacted by the electrode, said temperature sensor having a greater accuracy in the absence of interfering RF electrical noise caused by said RF current passing through said thermally conductive electrode than in the presence of said interfering RF electrical noise, feedback means connecting said sensor to a control circuit, said control circuit being constructed to modulate RF power applied to said electrode according to the signal received from said temperature sensor, said control circuit and RF power supply constructed to alternate between two operating modes, in the first mode said RF power supply applying RF power to said electrode, in the second mode said control circuit sensing a signal from said temperature sensor in the absence of RF signal, said control circuit constructed to compare the signal from said temperature sensor to a set value and to modulate the RF power applied to said electrode in accordance with said set value.
13. A radiofrequency medical device for ohmic heating of tissue of a patient in order to induce coagulation, comprising a guidewire probe, a plurality of RF patient-contacting conductors between which RF current of a frequency in the range of about 100 kilohertz to 100 megahertz flows for tissue-coagulation, at least one of said conductors being a thermally conductive electrode, located on said guidewire probe, that concentrates RF current in a local region of the patient's tissue contacted by said electrode, means to connect said electrode to one pole of an RF power supply, means to connect a second pole of said RF power supply to the patient via a second said conductor, a temperature sensor carried by and in thermally conductive relationship with said thermally conductive electrode, said temperature sensor being
constructed and arranged to sense the temperature of said electrode, and thereby to sense indirectly the temperature of tissue contacted by the electrode, said temperature sensor having a greater accuracy in the absence of interfering RF electrical noise caused by said RF current passing through said thermally conductive electrode than in the presence of said interfering RF electrical noise-, feedback means
connecting said sensor to a control circuit, said control circuit being constructed to modulate RF power applied to said electrode according to the signal received from said
temperature sensor, said control circuit and RF power supply constructed to alternate between two operating modes, in the first mode said RF power supply applying RF power to said electrode, in the second mode said control circuit sensing a signal from said temperature sensor in the absence of RF signal, said control circuit constructed to compare the signal from said temperature sensor to a set value and to modulate the RF power applied to said electrode in accordance with said set value.
14. The RF medical device of claim 13 wherein
said electrode comprises a tip of said guidewire probe,
said guidewire probe is constructed for thermally occluding ducts,
said guidewire probe is coated with insulation except at said electrode tip of said probe,
and said thermistor is mounted within said tip of said guidewire probe.
15. The RF medical device of claim 14 wherein said guidewire probe has structural dimensions suitable for
thermally occluding seminal ducts.
16. The RF medical device of claim 14 wherein said guidewire probe has structural dimensions suitable for
thermally occluding fallopian tubes.
17. A radiofrequency medical device for ohmic heating of tissue of a patient in order to induce coagulation, comprising a percutaneous probe constructed for insertion into a patient's body, a plurality of patient-contacting RF
conductors between which RF current of a frequency in the range of about 100 kilohertz to 100 megahertz flows for tissue-coagulation, at least one of said conductors being a thermally conductive electrode, located on said percutaneous probe, that concentrates RF current in a local region of the 10 patient's tissue contacted by said electrode, means to connect

11 said electrode to one pole of an RF power supply, means to

12 connect a second pole of said RF power supply to the patient

13 via a second said conductor, a temperature sensor carried by

14 and in thermally conductive relationship with said thermally

15 conductive electrode, said temperature sensor being
6 constructed and arranged to sense the temperature of said 7 electrode, and thereby to sense indirectly the temperature of 8 tissue contacted by the electrode, said temperature sensor 9 having a greater accuracy in the absence of interfering RF 0 electrical noise caused by said RF current passing through 1 said thermally conductive electrode than in the presence of 2 said interfering RF electrical noise, feedback means
3 connecting said sensor to a control circuit, said control
4 circuit being constructed to modulate RF power applied to said 5 electrode according to the signal received from said
6 temperature sensor, said control circuit and RF power supply 7 constructed to alternate between two operating modes, in the 8 first mode said RF power supply applying RF power to said 9 electrode, in the second mode said control circuit sensing a 0 signal from said temperature sensor in the absence of RF
1 signal, said control circuit constructed to compare the signal 2 from said temperature sensor to a set value and to modulate 3 the RF power applied to said electrode in accordance with said ^ set value.
18. The RF medical device of claim 17 wherein
said percutaneous probe comprises a needle,
said needle is constructed for percutaneous
electrode coagulation treatment of liver metastases,
and said electrode comprises a tip of said needle.
19. The RF medical device of claim 17 wherein
said percutaneous probe comprises a needle,
said needle is constructed for transrectal electrode coagulation treatment of prostatic tumors,
and said electrode comprises a tip of said needle.
20. A radiofrequency medical device for ohmic
heating of tissue of a patient in order to induce coagulation, comprising a thermal ablation probe -constructed for thermal ablation therapy for arrhythmias, a plurality of patient-contacting RF conductors between which RF current of a
frequency in the range of about 100 kilohertz to 100 megahertz flows for tissue-coagulation, at least one of said conductors being a thermally conductive electrode, mounted on said thermal ablation probe, that concentrates RF current in a local region of the patient's tissue contacted by said
electrode, means to connect said electrode to one pole of an RF power supply, means to connect a second pole of said RF power supply to the patient via a second said conductor, a temperature sensor carried by and in thermally conductive relationship with said thermally conductive electrode, said temperature sensor being constructed and arranged to sense the temperature of said electrode, and thereby to sense indirectly the temperature of tissue contacted by the electrode, said temperature sensor having a greater accuracy in the absence of interfering RF electrical noise caused by said RF current passing through said thermally conductive electorde than in the presence of said interfering RF electrical noise, feedback means connecting said sensor to a control circuit, said control circuit being constructed to modulate RF power applied to said electrode according to the signal received from said temperature sensor, said control circuit and RF power supply constructed to alternate between two operating modes, in the first mode said RF power supply applying RF power to said electrode, in the second mode said control circuit sensing a signal from said temperature sensor in the absence of RF signal, said control circuit constructed to compare the signal from said temperature sensor to a set value and to modulate the RF power applied to said electrode in accordance with said set value.
21. An electrode device for use with a
radiofrequency medical device for ohmic heating of tissue of a patient in order to induce coagulation, said electrode device comprising
a thermally conductive electrode that concentrates RF current of a frequency in the range of about 100 kilohertz to 100 megahertz in a local region of the patient's tissue contacted by said electrode, and
a temperature sensor carried by and in thermally conductive relationship with said thermally conductive electrode, said temperature sensor being constructed and arranged to sense the temperature of said electrode and thereby to sense indirectly the temperature of tissue
contacted by the electrode, said temperature sensor having a greater accuracy in the absence of interfering RF electrical noise caused by said RF current passing through said thermally conductive electrode than in the presence of said interfering RF electrical noise,
said radiofrequency medical device comprising
a patient-contacting RF conductor, said RF current flowing between said thermally conductive electrode and said F conductor for tissue-coagulation,
means to connect said electrode to one pole of an RF power supply,
means to connect a second pole of said RF power supply to the patient via a second said conductor,
and means connecting said sensor to a control circuit, said control circuit being constructed to modulate RF power applied to said electrode according to the signal received from said temperature sensor, said control circuit and RF power supply constructed to alternate between two operating modes, in the first mode said RF power supply applying RF power to said electrode, in said second mode said control circuit sensing a signal from said temperature sensor in the absence of RF signal, said control circuit constructed to compare the signal from said temperature sensor to a set value and to modulate the RF power applied to said electrode in accordance with said set value.
22. The electrode device of claim 21 wherein the period of temperature sensing is of the order of 1 percent of the cycle time.
23. The electrode device of claim 21 wherein said set value is a user set reference signal internal to said control circuit, and said control circuit is constructed and arranged to modulate RF power applied to said electrode to cause said temperature of said temperature sensor to approach a temperature represented said reference signal, thereby to control the temperature of said electrode and consequently the temperature of tissue contacted by the electrode.
24. A radiofrequency medical device for ohmic heating of tissue of a patient in order to induce coagulation, comprising a plurality of patient-contacting RF conductors between which RF current of a frequency in the range of about 100 kilohertz to 100 megahertz flows for tissue-coagulation, at least one of said conductors being. a thermally conductive electrode that concentrates RF current in a local region of tissue contacted by said electrode, an RF power supply, means to connect said electrode to one pole of said RF power supply, means to connect a second pole of said RF power supply to the patient via a second said conductor, a temperature sensor carried by and in thermally conductive relationship with said thermally conductive electrode, said temperature sensor being constructed and arranged to sense the temperature of said electrode and thereby to sense indirectly the temperature of tissue contacted by the electrode, said temperature sensor having a greater accuracy in the absence of interfering RF electrical noise caused by said RF current passing through said thermally conductive electrode than in the presence of said interfering RF electrical noise, a control circuit, means connecting said sensor to said control circuit, said control circuit being constructed to modulate RF power applied to said electrode according to the signal received from said
temperature sensor, said control circuit and RF power supply constructed to alternate between two operating modes, in the first mode said RF power supply applying RF power to said electrode, in said second mode said control circuit sensing a signal from said temperature sensor in the absence of RF signal, said control circuit constructed to compare the signal from said temperature sensor to a set value and to modulate the RF power applied to said electrode in accordance with said set value.
25. The RF medical device of claim 24 wherein the period of temperature sensing is of the order of 1 percent of the cycle time.
26. The RF medical device of claim 24 wherein said set value is a user set reference signal internal to said control circuit, and said control circuit is constructed and arranged to modulate RF power applied to said electrode to cause said temperature of said temperature sensor to approach a temperature represented said reference signal, thereby to control the temperature of said electrode and consequently the temperature of tissue contacted by the electrode.
27. A method of ohmic heating of tissue of a patient in order to induce coagulation, comprising the steps of
during a first mode, applying RF power to a
plurality of patient-contacting RF conductors in order to cause RF current of a frequency in the range of about 100 kilohertz to 100 megahertz to flow between said RF conductors for tissue-coagulation, at least one of said conductors being a thermally conductive electrode that concentrates RF current in a local region of the patient's tissue contacted by said electrode,
during a second mode, sensing, by means of a
temperature sensor carried by and in thermally conductive relationship with said thermally conductive electrode, the temperature of said electrode in the absence of RF signal, thereby to sense indirectly the temperature of tissue
contacted by the electrode, said temperature sensor having a greater accuracy in the absence of interfering RF electrical noise caused by said RF current passing through said thermally conductive electrode than in the presence of said interfering RF electrical noise,
comparing said sensed temperature to a set value, and modulating said RF power applied to said electrode in accordance with said sensed temperature and said set value.

28. The method of claim 27 wherein
said step of applying RF power to said plurality of RF conductors is performed by an RF power supply having one pole connected to said electrode and a second pole connected to a second said conductor,
and said steps of comparing said sensed temperature to a set value and modulating said RF power applied to said electrode are performed by a control circuit connected to said temperature sensor and constructed to modulate RF power applied to said electrode according to the signal received from said temperature sensor.
29. The method of claim 27 wherein
said set value is a user set reference signal,
and said step of modulating said RF power to said electrode comprises causing said temperature of said electrode to approach a temperature represented by said reference signal, thereby to control the temperature of said electrode and consequently the temperature of tissue contacted by the electrode.