# US 11,304,752 B2 · Estimation of lesion size

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- Number: US 11,304,752 B2
- Document ID: US11304752B2
- Status: Granted
- Kind: B2
- Application number: 16/728,951
- Filed: 2019-12-27
- Published: 2020-04-30
- Granted: 2022-04-19
- Earliest claimed: 2015-07-16
- Assignees: Biosense Webster (Israel) Ltd.; University of Oklahoma Health Sciences Center
- Applicants: Biosense Webster (Israel) Ltd.; University of Oklahoma Health Sciences Center
- Inventors: Meir Bar-Tal; Erez Silberschein; Assaf Rubissa; Garth Francis Constantine; Hiroshi Nakagawa
- Web page: https://patentgrep.com/patent/US11304752B2

## CPC

- A61B 18/1492: {having a flexible, catheter-like structure, e.g. for heart ablation (A61B18/1477 takes precedence)}
- A61B 18/1233: {with circuits for assuring patient safety}
- A61B 2018/00351: {Heart}
- A61B 2018/00577: {Ablation}
- A61B 2018/00648: {using more than one sensed parameter}
- A61B 2018/00678: {upper}
- A61B 2018/00708: {switching the power on or off}
- A61B 2018/00738: {Depth, e.g. depth of ablation}
- A61B 2018/00779: {Power or energy}
- A61B 2018/00827: {Current}
- A61B 2018/00886: {Duration}
- A61B 2018/00988: {Means for storing information, e.g. calibration constants, or for preventing excessive use, e.g. usage, service life counter}
- A61B 2090/065: {for measuring contact or contact pressure}
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)

## Abstract

A method, consisting of ablating tissue for a time period, measuring a contact force applied during the time period, and measuring a power used during the time period. The method further includes ceasing ablating the tissue when a desired size of a lesion produced in the tissue, as estimated using an integral over the time period of a product of the contact force raised to a first non-unity exponent and the power raised to a second non-unity exponent, is reached.

## Claims

### Claim 1

A method for ablating tissue over a time period, comprising:
providing a probe;
selecting a desired depth for a lesion as estimated by an ablation index defined as
Depthγ(T)=C∫0TCFα(t)Pβ(t)dt
wherein
F is an instantaneous contact force applied by the probe during the time period;
P is an instantaneous power applied by the probe during the time period;
T is the time period;
α, β and γ are numerical exponents having values not equal to unity; and
C is a constant of proportionality;
selecting values of α, β and γ;
ablating the tissue with the probe;
measuring the instantaneous contact force F;
measuring the instantaneous power; and
ceasing ablating the tissue when the desired depth of the lesion is produced in the tissue, as estimated using the ablation index.

### Claim 2 (depends on 1)

The method according to claim 1, wherein a has α value in a range of 0.6-0.8.

### Claim 3 (depends on 1)

The method according to claim 1, wherein β has a value in a range of 1.4-1.8.

### Claim 4 (depends on 1)

The method according to claim 1, wherein γ has a value of 2.78.

### Claim 5 (depends on 1)

The method according to claim 1, wherein measuring the instantaneous power comprises measuring a current generating the instantaneous power.

### Claim 6

An apparatus, comprising:
a probe configured to ablate tissue for a time period; and
a processor configured to:
energize the probe in accordance with an ablation index defined as:
Depthγ(T)=C∫0TCFα(t)Pβ(t)dt
wherein
F is an instantaneous contact force applied by the probe during the time period;
P is an instantaneous power applied by the probe during the time period;
T is the time period;
α, β and γ are user-selected numerical exponents having values not equal to unity; and
C is a constant of proportionality;
measure an instantaneous contact force applied by the probe during the time period,
measure an instantaneous power used for ablating the tissue during the time period, and
cease ablating the tissue when a desired depth of lesion is produced in the tissue, as estimated using the ablation index.

### Claim 7 (depends on 6)

The apparatus according to claim 6, wherein α has a value in a range of 0.6-0.8.

### Claim 8 (depends on 6)

The apparatus according to claim 6, wherein β has a value in a range of 1.4-1.8.

### Claim 9 (depends on 6)

The apparatus according to claim 6, wherein the processor is further configured to measure a current generating the instantaneous power.