# US 9,750,570 B2 · Systems and methods for detecting tissue contact during ablation

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- Number: US 9,750,570 B2
- Document ID: US9750570B2
- Status: Granted
- Kind: B2
- Application number: 14/934,855
- Filed: 2015-11-06
- Published: 2016-03-03
- Granted: 2017-09-05
- Earliest claimed: 2012-05-01
- Assignees: Medtronic Ablation Frontiers LLC
- Applicants: Medtronic Ablation Frontiers LLC
- Inventors: Catherine R. Condie; Marshall L. Sherman; Mark T. Stewart
- Web page: https://patentgrep.com/patent/US9750570B2

## CPC

- A61B 18/1492: {having a flexible, catheter-like structure, e.g. for heart ablation (A61B18/1477 takes precedence)}
- A61B 90/06: {Measuring instruments not otherwise provided for}
- A61B 2018/0022: {Balloons}
- A61B 2018/00285: {Balloons}
- A61B 2018/00345: {Vascular system}
- A61B 2018/00577: {Ablation}
- A61B 2018/00642: {with feedback, i.e. closed loop control}
- A61B 2018/00708: {switching the power on or off}
- A61B 2018/00791: {Temperature}
- A61B 2018/00863: {Fluid flow}
- A61B 2018/00875: {Resistance or impedance}
- A61B 2018/00898: {Alarms or notifications created in response to an abnormal condition}
- A61B 2018/0212: {using an instrument inserted into a body lumen, e.g. catheter}
- A61B 2018/0262: {using a circulating cryogenic fluid}
- A61B 2018/1467: {using more than two electrodes on a single probe}
- A61B 2090/065: {for measuring contact or contact pressure}
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)

## Abstract

Systems and methods for assessing tissue contact, including positioning a plurality of electrodes adjacent a tissue region; delivering radiofrequency energy to the plurality of electrodes, wherein the delivered radiofrequency energy is sufficient to ablate at least a portion of the tissue region; obtaining a plurality of impedance measurements from the plurality of electrodes during the delivery of the radiofrequency energy; calculating a change in the impedance measurements for each of the plurality of electrodes over a pre-determined time period; comparing the calculated change for at least one of the plurality of electrodes to the calculated change in at least one other of the plurality of electrode to determine if there is significant variation in the calculated changes; and terminating the delivery of radiofrequency energy to at least one of the plurality if there is significant variation in the calculated changes.

## Claims

### Claim 1

A method of operating a medical device having a plurality of electrodes, comprising:
positioning the plurality of electrodes adjacent a tissue region;
delivering radiofrequency energy to each of the plurality of electrodes, wherein the delivered radiofrequency energy is sufficient to ablate at least a portion of the tissue region;
obtaining a plurality of impedance measurements from each of the plurality of electrodes during the delivery of the radiofrequency energy;
calculating a change in the impedance measurements for each of the plurality of electrodes over a pre-determined time period;
comparing the calculated change for at least one of the plurality of electrodes to the calculated change for at least one of the other plurality of electrodes; and
terminating the delivery of radiofrequency energy to at least one of the plurality of electrodes based at least in part on the comparison.

### Claim 2 (depends on 1)

The method of claim 1, further comprising:
attributing the calculated change in the impedance measurements to a tissue contact condition; and
generating an alert that signals the tissue contact condition.

### Claim 3 (depends on 1)

The method of claim 1, wherein the pre-determined time period is between approximately 5 seconds and approximately 20 seconds.

### Claim 4 (depends on 1)

The system of claim 1, wherein each of the plurality of electrodes includes a sensor.