Detecting lead dislodgement during atrial fibrillation

1. A method of detecting dislodgement of a lead coupled to an implantable medical device, the method comprising:

sensing, by sensing circuitry of the implantable medical device, a cardiac signal via the lead;

determining, by processing circuitry, at least one characteristic of the cardiac signal associated with dislodgement of the lead during atrial fibrillation;

detecting, by the processing circuitry, dislodgement of the lead based on the determined at least one characteristic; and

providing, by the processing circuitry, a lead dislodgement alert in response to detecting the dislodgement of the lead.

2. The method of claim 1 , further comprising:

detecting, by the processing circuitry, a fibrillation episode based on the sensed cardiac signal; and

withholding, by the processing circuitry, delivery of a defibrillation therapy by the implantable medical device to treat the detected fibrillation based on detecting the dislodgement of the lead.

3. The method of claim 2 , wherein determining the at least one characteristic of the cardiac signal associated with dislodgement of the lead during atrial fibrillation comprises determining the at least one characteristic in response to the fibrillation episode being detected.

4. The method of claim 3 , further comprising determining, by the processing circuitry, whether a lead dislodgement withholding feature is enabled, wherein at least one of:

determining the at least one characteristic of the cardiac signal associated with dislodgement of the lead during atrial fibrillation comprises determining the at least one characteristic in response to the withholding feature being enabled and the fibrillation episode being detected; or

withholding delivery of the defibrillation therapy to treat the detected fibrillation episode comprises withholding the delivery of the defibrillation therapy based on the withholding feature being enabled and detecting the dislodgement of the lead.

5. The method of claim 4 , further comprising:

determining, by the processing circuitry, that an atrial fibrillation episode has been detected; and

enabling, by the processing circuitry, the withholding feature based on the atrial fibrillation episode being detected.

6. The method of claim 4 , further comprising:

determining, by the processing circuitry, whether the lead has been implanted for less than a predetermined time period; and

enabling, by the processing circuitry, the withholding feature based on the lead being implanted for less than the predetermined time period.

7. The method of claim 4 , further comprising controlling, by the processing circuitry, delivery of the defibrillation therapy by the implantable medical device based on detecting the dislodgement of the lead and the withholding feature being disabled.

8. The method of claim 1 , wherein determining the at least one characteristic of the cardiac signal associated with dislodgement of the lead during an atrial fibrillation episode comprises determining a variability of RR intervals of the cardiac signal, and wherein detecting dislodgement of the lead comprises detecting dislodgement of the lead based on the variability satisfying a variability threshold.

9. The method of claim 8 , wherein determining a variability of RR intervals comprises determining at least one of a modesum of the RR intervals or a ratio of a maximum and a minimum of the RR intervals, and detecting dislodgement of the lead based on the variability satisfying a variability threshold comprises detecting dislodgement of the lead based on at least one of the modesum being less than a predetermined modesum percentage or the ratio satisfying a ratio threshold.

10. The method of claim 9 , wherein the cardiac signal comprises a near-field cardiac signal, wherein determining at least one characteristic of the cardiac signal associated with dislodgement of the lead during an atrial fibrillation episode comprises determining an amplitude of the near-field cardiac signal, and wherein detecting dislodgement of the lead comprises detecting dislodgement of the lead based on the amplitude being less than an amplitude threshold.

11. The method of claim 10 , wherein determining an amplitude of the near-field cardiac signal comprises determining an amplitude for each of a plurality of detected R-waves, and wherein detecting dislodgement of the lead based on the amplitude being less than an amplitude threshold comprises detecting dislodgement of the lead based on the amplitude of a threshold number of detected R-waves being less than the amplitude threshold.

12. The method of claim 1 , wherein the cardiac signal comprises a near-field cardiac signal, wherein determining at least one characteristic of the near-field cardiac signal associated with dislodgement of the lead during an atrial fibrillation episode comprises determining an amplitude of the near-field cardiac signal, and wherein detecting dislodgement of the lead comprises detecting dislodgement of the lead based on the amplitude being less than an amplitude threshold.

13. The method of claim 12 , wherein determining an amplitude of the near-field cardiac signal comprises determining an amplitude for each of a plurality of detected R-waves, and wherein detecting dislodgement of the lead based on the amplitude being less than an amplitude threshold comprises detecting dislodgement of the lead based on the amplitude of a threshold number of detected R-waves being less than the amplitude threshold.

14. A medical device system comprising:

a lead comprising a plurality of electrodes; and

sensing circuitry configured to sense a cardiac signal via at least one of the plurality of electrodes of the lead; and

processing circuitry configured to:

determine at least one characteristic of the cardiac signal associated with dislodgement of the lead during atrial fibrillation;

detect dislodgement of the lead based on the determined at least one characteristic; and

provide a lead dislodgement alert in response to detecting the dislodgement of the lead.

15. The system of claim 14 , further comprising therapy delivery circuitry configured to deliver a defibrillation therapy, wherein the processing circuitry is configured to:

detect a fibrillation episode based on the sensed cardiac signal; and

withholding delivery of the defibrillation therapy by the therapy delivery circuitry to treat the detected fibrillation based on detecting the dislodgement of the lead.

16. The system of claim 15 , wherein the processing circuitry is configured to determine the at least one characteristic of the cardiac signal associated with dislodgement of the lead during atrial fibrillation in response to the fibrillation episode being detected.

17. The system of claim 16 , wherein the processing circuitry is configured to determine whether a lead dislodgement withhold feature has been enabled, and at least one of:

determine the at least one characteristic of the cardiac signal associated with dislodgement of the lead during atrial fibrillation in response to the withholding feature being enabled and the fibrillation episode being detected; or

withhold the delivery of the defibrillation therapy by the therapy delivery circuitry to treat the detected fibrillation episode based on the withholding feature being enabled and detecting the dislodgement of the lead.

18. The system of claim 17 , wherein the processing circuitry is configured to determine whether an atrial fibrillation episode has been detected, and enable the withholding feature based on the atrial fibrillation episode being detected.

19. The system of claim 17 , wherein the processing circuitry is configured to determine whether the lead has been implanted for less than a predetermined time period, and enable the withholding feature based on the lead being implanted for less than the predetermined time period.

20. The system of claim 17 , wherein the processing circuitry is configured to control the therapy delivery circuitry to deliver the defibrillation therapy based on the episode being detected and the withhold feature being disabled.