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US 10,206,733 B2Granted
System for controlling tissue ablation using temperature sensors
AssigneeBiosense Webster (Israel) Ltd.
InventorsAssaf Govari, Yaron Ephrath, Andres Claudio Altmann
Life of this patent
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Abstract
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.
Claims19
A method for ablating body tissue, comprising:
- inserting a probe into a body of a 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 by performing magnetic resonance imaging concurrently with the transmitting of the generated ablative energy;
- determining 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 level;
- 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, wherein the control function is:
- I
- new
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- k
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- P
- targ
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-
- or
- I
- new
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- kC
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- 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 temperature;
- Ttarg is the target temperature;
- k is a damping constant;
- and
- C is a constant having a value of −1 if both Pmeas is greater than Ptarg and Tmeas is greater than Ttarg, and +1 otherwise;
- and
- controlling 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.
80 more elements
An ablation system, comprising:
- a catheter having a distal portion for insertion into a body and configured to bring the distal portion into contact with a tissue in the body;
- 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 of the catheter, 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;
- one or more magnetic resonance imaging field magnets configured to generate magnetic resonance imaging signals;
- a processor operative for determining a measured temperature of the tissue from the magnetic resonance imaging signals, and to determine 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, wherein the control function is:
- I
- new
- =
- I
- present
- +
- k
-
-
- Min
-
- {
- (
- P
- targ
- -
- P
- meas
- P
- targ
- )
- ,
- (
- T
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- -
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- meas
- T
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- )
- }
- ,
-
- or
- I
- new
- =
- I
- present
- +
- kC
-
- (
- P
- targ
- -
- P
- meas
- P
- targ
- )
-
- (
- T
- targ
- -
- T
- meas
- T
- targ
- )
- 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 temperature;
- Ttarg is a target temperature;
- k is a damping constant;
- and
- C is a constant having a value of −1 if both Pmeas is greater than Ptarg and Tmeas is greater than Ttarg, and +1 otherwise;
- and
- control 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.
79 more elements
Dependencies are inferred from the claim text.