# US 11,432,872 B2 · Energy-guided radiofrequency (RF) ablation

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- Number: US 11,432,872 B2
- Document ID: US11432872B2
- Status: Granted
- Kind: B2
- Application number: 16/288,838
- Filed: 2019-02-28
- Published: 2020-09-03
- Granted: 2022-09-06
- Earliest claimed: 2019-02-28
- Assignees: Biosense Webster (Israel) Ltd.
- Applicants: Biosense Webster (Israel) Ltd.
- Inventors: Assaf Govari; Andres Claudio Altmann; Ella Ozeri
- Web page: https://patentgrep.com/patent/US11432872B2

## CPC

- A61B 18/1492: {having a flexible, catheter-like structure, e.g. for heart ablation (A61B18/1477 takes precedence)}
- A61B 18/1206: {Generators therefor}
- A61B 2018/00011: {with fluids}
- A61B 2018/00029: {open}
- A61B 2018/00351: {Heart}
- A61B 2018/00357: {Endocardium}
- A61B 2018/00577: {Ablation}
- A61B 2018/00678: {upper}
- A61B 2018/00702: {Power or energy}
- A61B 2018/00744: {Fluid flow}
- A61B 2018/00791: {Temperature}
- A61B 2018/00875: {Resistance or impedance}
- A61B 2018/00886: {Duration}
- A61B 2218/002: Irrigation
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)

## Abstract

A method of body tissue ablation includes defining a target amount of ablation energy needed to create a specified lesion in tissue in a body of a patient. Contact is made between an ablation probe and the tissue. Using the ablation probe, an ablation signal is applied to the tissue, which delivers the target amount of ablation energy during a smallest time duration permitted within a defined maximum-power constraint.

## Claims

### Claim 1

A method of body tissue ablation, the method comprising:
a) setting ablation parameters needed to create a specified lesion in tissue in a body of a patient using an ablation probe having an electrode, the ablation parameters comprising a target amount of ablation energy, a predetermined temperature range of the tissue, a range of power to be delivered to the electrode, the range including a maximum power level, and a preset period of time;
b) determining that an impedance of the electrode does not exceed a preset impedance value;
c) applying an ablation signal to the tissue to deliver the target amount of ablation energy during a smallest time duration within the preset period of time using the maximum power level;
d) modifying an irrigation flow rate in response to a determination that a monitored tissue temperature equals or exceeds a maximum temperature within the preset temperature range;
e) modifying the power in response to a determination that the monitored tissue temperature equals or exceeds the maximum temperature after modifying the irrigation flow rate;
f) discontinuing the ablation signal in response to one of:
i) a determination that the monitored tissue temperature equals or exceeds the maximum temperature after modifying the irrigation flow rate and power,
ii) a determination that the monitored tissue temperature does not equal or exceed the maximum temperature after one of modifying the irrigation flow rate or power and a determination that the target amount of ablation energy has been achieved, or
iii) a determination that the monitored tissue temperature does not equal or exceed the maximum temperature after one of modifying the irrigation flow rate or power, a determination that the target amount of ablation energy has not been achieved and a determination that the preset period of time has been exceeded; and
g) returning to step b) if the ablation is not discontinued pursuant to step f).

### Claim 2 (depends on 1)

The method according to claim 1, and comprising, if the monitored temperature exceeds the defined maximum temperature but the flow of the irrigation fluid exceeds a defined maximum-flow limit, reducing the power and extending the time duration of the ablation signal.

### Claim 3 (depends on 1)

The method according to claim 1, wherein monitoring the temperature comprises measuring the temperature of the electrode that delivers the ablation signal to the tissue.

### Claim 4 (depends on 1)

The method according to claim 1, and comprising extending a duration of ablation until the target amount of ablation energy to be applied to the tissue is reached.

### Claim 5 (depends on 1)

The method according to claim 1, and comprising, during application of the ablation signal:
applying irrigation fluid in a vicinity of the tissue;
monitoring a temperature in the vicinity of the tissue; and
if the monitored temperature exceeds the maximum temperature, decreasing the power to keep the temperature at the maximum temperature.

### Claim 6 (depends on 5)

The method according to claim 5, and comprising, during application of the ablation signal, if the power is decreasing, increasing the irrigation flow to reduce the temperature below the maximum temperature and subsequently increasing the power to the maximum power level.

### Claim 7 (depends on 1)

The method according to claim 1, and comprising, during application of the ablation signal, if the target amount of ablation energy is not met during the preset period of time, discontinuing the ablation signal.

### Claim 8

A system comprising:
one or more processors; and
a non-transitory computer readable medium storing a plurality of instructions, which when executed, cause the one or more processors to:
a) set ablation parameters needed to create a specified lesion in tissue in a body of a patient using an ablation probe having an electrode, the ablation parameters comprising a target amount of ablation energy, a predetermined temperature range of the tissue, a range of power to be delivered to the electrode, the range including a maximum power level, and a preset period of time;
b) determine that an impedance of the electrode does not exceed a preset impedance value;
c) apply an ablation signal to the tissue to deliver the target amount of ablation energy during a smallest time duration within the preset period of time using the maximum power level;
d) modify an irrigation flow rate in response to a determination that a measured tissue temperature equals or exceeds a maximum temperature within the preset temperature range;
e) modify the power in response to a determination that the measured tissue temperature equals or exceeds the maximum temperature after modifying the irrigation flow rate;
f) discontinue the ablation signal in response to one of:
i) a determination that the measured tissue temperature equals or exceeds the maximum temperature after modifying the irrigation flow rate and power,
ii) a determination that the measured tissue temperature does not equal or exceed the maximum temperature after one of modifying the irrigation flow rate or power and a determination that the target amount of ablation energy has been achieved, or
iii) a determination that the measured tissue temperature does not equal or exceed the maximum temperature after one of modifying the irrigation flow rate or power, a determination that the target amount of ablation energy has not been achieved and a determination that the preset period of time has been exceeded; and
g) return to step b) if the ablation is not discontinued pursuant to step f).

### Claim 9 (depends on 8)

The system according to claim 8, wherein, if the monitored temperature exceeds the defined maximum temperature but the flow of the irrigation fluid exceeds a defined maximum-flow limit, the plurality of instructions, when executed, will further cause the one or more processors to reduce the power and extend the time duration of the ablation signal.

### Claim 10 (depends on 8)

The system according to claim 8, wherein the monitored temperature is the temperature of the electrode that delivers the ablation signal to the tissue.

### Claim 11 (depends on 8)

The system according to claim 8, wherein the plurality of instructions, when executed, will further cause the one or more processors to control the generator to extend a duration of ablation until the target amount of ablation energy to be applied to the tissue is reached.

### Claim 12 (depends on 8)

The system according to claim 8, wherein the plurality of instructions, when executed, will further cause the one or more processors to, during application of the ablation signal:
apply irrigation fluid in a vicinity of the tissue;
monitor a temperature in the vicinity of the tissue; and
if the monitored temperature exceeds the maximum temperature, decreasing the power to keep the temperature at the maximum temperature.

### Claim 13 (depends on 12)

The system according to claim 12, wherein the plurality of instructions, when executed, will further cause the one or more processors to, during application of the ablation signal, if the power is decreasing, increasing the irrigation flow to reduce the temperature below the maximum temperature and subsequently increasing the power to the maximum power level.

### Claim 14

A computer program product, comprising a non-transitory computer-readable medium having computer-readable program code embodied therein to be executed by one or more processors, the program code including instructions to:
a) set ablation parameters needed to create a specified lesion in tissue in a body of a patient using an ablation probe having an electrode, the ablation parameters comprising a target amount of ablation energy, a predetermined temperature range of the tissue, a range of power to be delivered to the electrode, the range including a maximum power level, and a preset period of time;
b) determine that an impedance of the electrode does not exceed a preset impedance value;
c) apply an ablation signal to the tissue to deliver the target amount of ablation energy during a smallest time duration within the preset period of time using the maximum power level;
d) modify an irrigation flow rate in response to a determination that a measured tissue temperature equals or exceeds a maximum temperature within the preset temperature range;
e) modify the power in response to a determination that the measured tissue temperature equals or exceeds the maximum temperature after modifying the irrigation flow rate;
f) discontinue the ablation signal in response to one of:
i) a determination that the measured tissue temperature equals or exceeds the maximum temperature after modifying the irrigation flow rate and power,
ii) a determination that the measured tissue temperature does not equal or exceed the maximum temperature after one of modifying the irrigation flow rate or power and a determination that the target amount of ablation energy has been achieved, or
iii) a determination that the measured tissue temperature does not equal or exceed the maximum temperature after one of modifying the irrigation flow rate or power, a determination that the target amount of ablation energy has not been achieved and a determination that the preset period of time has been exceeded; and
g) return to step b) if the ablation is not discontinued pursuant to step f).

### Claim 15 (depends on 14)

The computer program product according to claim 14, wherein the program code includes further instructions to reduce the power and extend the time duration of the ablation signal if the monitored temperature exceeds the defined maximum temperature and the flow of the irrigation fluid exceeds a defined maximum-flow limit.

### Claim 16 (depends on 14)

The computer program product according to claim 14, wherein the monitored temperature is the temperature of the electrode that delivers the ablation signal to the tissue.

### Claim 17 (depends on 14)

The computer program product according to claim 14, wherein the program code includes further instructions to control the generator to extend a duration of ablation until the target amount of ablation energy to be applied to the tissue is reached.

### Claim 18 (depends on 14)

The computer program product according to claim 14, wherein the program code includes further instructions to, during application of the ablation signal:
apply irrigation fluid in a vicinity of the tissue;
monitor a temperature in the vicinity of the tissue; and
if the monitored temperature exceeds the maximum temperature, decreasing the power to keep the temperature at the maximum temperature.

### Claim 19 (depends on 18)

The computer program product according to claim 18, wherein the plurality of instructions, when executed, will further cause the one or more processors to, during application of the ablation signal, if the power is decreasing, increasing the irrigation flow to reduce the temperature below the maximum temperature and subsequently increasing the power to the maximum power level.