SYSTEM FOR CONTROLLING TISSUE ABLATION USING TEMPERATURE SENSORS
원문보기
IPC분류정보
국가/구분
United States(US) Patent
공개
국제특허분류(IPC7판)
A61B-018/12
A61B-018/20
A61B-090/00
A61B-018/00
A61N-007/02
A61B-018/24
A61B-018/14
A61B-005/055
A61B-005/01
A61B-017/00
출원번호
US-0682445
(2017-08-21)
공개번호
US-0348040
(2017-12-07)
발명자
/ 주소
Govari, Assaf
Ephrath, Yaron
Altmann, Andres Claudio
출원인 / 주소
Govari, Assaf
인용정보
피인용 횟수 :
0인용 특허 :
0
초록▼
Body tissue ablation is carried out by inserting a probe into a body of a living subject, urging the probe into contact with a tissue in the body, generating energy at a power output level, and transmitting the generated energy into the tissue via the probe. While transmitting the generated energy t
Body tissue ablation is carried out by inserting a probe into a body of a living subject, urging the probe into contact with a tissue in the body, generating energy at a power output level, and transmitting the generated energy into the tissue via the probe. While transmitting the generated energy the ablation is further carried out by determining a measured temperature of the tissue and a measured power level of the transmitted energy, and controlling the power output level responsively to a function of the measured temperature and the measured power level. Related apparatus for carrying out the ablation is also described.
대표청구항▼
1. A method of body tissue ablation, comprising: inserting a probe into a body of a living subject;urging the probe into contact with a tissue in the body;generating ablative energy at a power output level at a level of current;transmitting the generated ablative energy into the tissue via the probe
1. A method of body tissue ablation, comprising: inserting a probe into a body of a living subject;urging the probe into contact with a tissue in the body;generating ablative energy at a power output level at a level of current;transmitting the generated ablative energy into the tissue via the probe;determining a measured temperature of the tissue and a measured power level of the generated ablative energy during the transmitting of the generated ablative energy into the tissue;determining a power deviation by comparing a difference between the measured power level and a predetermined target power value;determining a temperature deviation by comparing a difference between the measured temperature of the tissue and a predetermined target temperature;calculating a target current value from a control function selected from: Inew=Ipresent+kMin{(Ptarg-PmeasPtarg),(Ttarg-TmeasTtarg)}orInew=Ipresent+kC(Ptarg-PmeasPtarg)(Ttarg-TmeasTtarg),in which: Inew is the target current value;Ipresent is the target current value in a previous iteration;Pmeas is the measured power level;Ptarg is the target power level;Tmeas is the measured temperatureTtarg is the target temperature;k is a damping constant; andC is a constant having a value of −1 if both Pmeas is greater than Ptarg and Tmeas is greater than Ttarg, and +1 otherwise; andcontrolling the power output level responsively to the calculated target current value by incrementally adjusting the level of current to the target current value gradually over time to generate the ablative energy at a new power output level until the measured temperature of the tissue reaches the predetermined target temperature and the measured power level reaches the predetermined target power, the controlling the power output level further comprising restricting or terminating the generation of the ablative energy when a predetermined ablation condition is met. 2. The method according to claim 1, wherein the generated energy is radiofrequency energy, ultrasound energy or laser-produced light energy. 3. The method according to claim 1, wherein the predetermined ablation condition comprises: power required for generating ablative energy exceeds abailable power; ora change in impedance that exceeds a predetermined impedance value; ora change in temperature that exceeds a predetermined maximum temperature; orfailure to exceed a predetermined minimum temperature;power output exceeding the target power level; orelapsed ablation time exceeding a predetermined maximum ablation time; orviolating a predetermined minimum flow rate. 4. The method according to claim 1, wherein the controlling the power output level further comprises terminating the generation of ablative energy when the ablation condition comprises: a change in impedance that exceeds a predetermined impedance value; ora change in temperature that exceeds a predetermined maximum temperature; orfailure to exceed a predetermined minimum temperature;power output exceeding the target power level; orelapsed ablation time exceeding a predetermined maximum ablation time; orviolating a predetermined minimum flow rate. 5. The method according to claim 1, wherein the controlling the power output level further comprises terminating the generation of ablative energy when the ablation condition comprises: power required for generating ablative energy exceeds abailable power. 6. The method according to claim 1, wherein determining the measured temperature is performed using magnetic resonance imaging analysis or ultrasound imaging analysis. 7. The method according to claim 1, wherein the measured temperature is an electrode temperature. 8. The method according to claim 1, wherein the determining the power deviation, determining the temperature deviation, calculating the target current value, and controlling the power output level are performed iteratively. 9. The method according to claim 8, wherein the determining the power deviation, determining the temperature deviation, calculating the target current value, and controlling the power output level are iterated 10 times per second. 10. The method according to claim 8, wherein the determining the power deviation, determining the temperature deviation, calculating the target current value, and controlling the power output level are iterated 5-50 times per second. 11. The method according to claim 1, wherein the controlling the power output level is performed by limiting an increment or decrement thereof so as not to exceed a predetermined limiting condition, wherein the limiting condition is selected from the group consisting of a maximum current, a minimum electrode temperature, a maximum electrode temperature, a maximum temperature of the tissue, and a maximum power demand. 12. An ablation apparatus, comprising: a catheter, having a distal portion for insertion into a body cavity of a living subject and configured to bring the distal portion into contact with a tissue in the body cavity;a power generator for generating ablative energy at a power output level having a level of current;an ablation element disposed on the distal portion, configured to accept the ablative energy from the power generator via the catheter and to conduct the ablative energy to the tissue for ablation of the tissue; anda processor operative for determining a measured temperature of the tissue and a measured power level of the ablative energy conducted through the ablation element, the processor configured to: determine a power deviation by comparing a difference between the measured power level and a predetermined target power level;determine a temperature deviation by comparing a difference between the measured temperature of the tissue and a predetermined target temperature;calculate a target current value from a control function selected from: Inew=Ipresent+kMin{(Ptarg-PmeasPtarg),(Ttarg-TmeasTtarg)}orInew=Ipresent+kC(Ptarg-PmeasPtarg)(Ttarg-TmeasTtarg),in which:Inew is the target current value;Ipresent is the target current value in a previous iteration;Pmeas is measured power;Ptarg is a target power level;Tmeas is measured temperatureTtarg is a target temperature;k is a damping constant; andC is a constant having a value of −1 if both Pmeas is greater than Ptarg and Tmeas is greater than Ttarg, and +1 otherwise; andcontrol the power output level responsively to the calculated target current value by incrementally adjusting the level of current to the target current value gradually over time to generate the ablative energy at a new power output level until the measured temperature of the tissue reaches the predetermined target temperature and the measured power level reaches the predetermined target power level. 13. The ablation apparatus according to claim 12, wherein the ablation element comprises at least one ablation electrode, and the ablation apparatus further comprises a temperature sensor for each ablation electrode, and wherein the processor is configured to determine the measured temperature of the tissue from the temperature sensor. 14. The ablation apparatus according to claim 12, wherein the measured temperature is a temperature of the ablation element. 15. The ablation apparatus according to claim 12, wherein the processor is configured to determine the measured temperature of the tissue by analyzing magnetic resonance imaging that is performed concurrently with the generation of ablative energy. 16. The ablation apparatus according to claim 15, wherein the processor is configured to acquire magnetic resonance imaging signals from field magnets, and enhance the magnetic resonance signals by a peak calculation module that is linked to a temperature analyzer, the temperature analyzer providing a thermometry signal to a port of an ablation module of the processor. 17. The ablation apparatus according to claim 12, wherein the determining the power deviation, determining the temperature deviation, calculating the target current value, and controlling the power output level are performed iteratively. 18. The ablation apparatus according to claim 17, wherein the determining the power deviation, determining the temperature deviation, calculating the target current value, and controlling the power output level are iterated 10 times per second. 19. The ablation apparatus according to claim 12, wherein the determining the power deviation, determining the temperature deviation, calculating the target current value, and controlling the power output level are iterated 5-50 times per second. 20. The ablation apparatus according to claim 12, wherein the controlling the power output level is performed by limiting an increment or decrement thereof so as not to exceed a predetermined limiting condition, wherein the limiting condition is selected from the group consisting of a maximum current, a minimum electrode temperature, a maximum electrode temperature, a maximum temperature of the tissue, and a maximum power demand.
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