Method and apparatus for verifying bradycardia/asystole episodes via detection of under-sensed events

1. A medical device comprising:

sensing circuitry configured to monitor an electrogram (EGM) signal;

a primary sensing channel configured to apply a primary threshold to the EGM signal to detect R-waves within the EGM signal;

a secondary sensing channel configured to apply a secondary threshold to the EGM signal to detect under-sensed R-waves within the EGM signal; and

a processor configured to:

detect at least one of bradycardia or asystole based on one or more R-waves detected by the primary sensing channel,

determine that the secondary sensing channel detected an under-sensed R-wave between R-waves detected by the primary sensing channel, and

determines that the detected bradycardia or asystole is false based on the detection of the under-sensed R-waves.

2. The medical device of claim 1 , wherein the primary threshold is a primary auto-adjusting threshold and the secondary threshold is a secondary auto-adjusting threshold, wherein the secondary auto-adjusting threshold decays to a minimum value more quickly than the primary auto-adjusting threshold.

3. The medical device of claim 2 , wherein the secondary auto-adjusting threshold is initialized to a maximum value following the detected under-sensed R-wave, wherein the maximum value is a function of an amplitude of the detected under-sensed R-wave, and wherein the maximum value associated with the secondary auto-adjusting threshold is less than a maximum value associated with the primary auto-adjusting threshold.

4. The medical device of claim 1 , wherein the primary sensing channel includes a primary band-pass filter applied to the monitored EGM signal to generate a primary filtered EGM signal compared to the primary threshold to detect R-waves.

5. The medical device of claim 4 , wherein the secondary sensing channel includes a secondary band-pass filter applied to the monitored EGM signal to generate a secondary filtered EGM signal compared to the secondary threshold to detect under-sensed R-waves.

6. An insertable cardiac monitor comprising:

a first electrode located at a distal end of the insertable cardiac monitor;

a second electrode located at a proximal end of the insertable cardiac monitor;

sensing circuitry coupled to the first electrode and second electrode and configured to monitor an electrogram (EGM) signal via the first electrode and the second electrode;

a primary sensing channel configured to apply a primary threshold to the EGM signal to sense R-waves within the EGM signal;

a secondary sensing channel configured to apply a secondary threshold to the EGM signal to detect under-sensed R-waves within the EGM signal; and

a processor configured to:

detect at least one of bradycardia or asystole based on one or more R-waves detected by the primary sensing channel,

determine that the secondary sensing channel detected an under-sensed R-wave between R-waves detected by the primary sensing channel, and

determine that the detected bradycardia or asystole is false based on the detection of the under-sensed R-waves.

7. The insertable cardiac monitor of claim 6 , further comprising a housing having a length, a width and a depth, wherein the length is much greater than the width and the width is greater than the depth.

8. The insertable cardiac monitor of claim 6 , wherein the primary threshold is a primary auto-adjusting threshold and the secondary threshold is a secondary auto-adjusting threshold, wherein the secondary auto-adjusting threshold decays to a minimum value more quickly than the primary auto-adjusting threshold.

9. The insertable cardiac monitor of claim 8 , wherein the secondary auto-adjusting threshold is initialized to a maximum value following the detected under-sensed R-wave, wherein the maximum value is a function of an amplitude of the detected under-sensed R-wave, and wherein the maximum value associated with the secondary auto-adjusting threshold is less than a maximum value associated with the primary auto-adjusting threshold.

10. The insertable cardiac monitor of claim 6 , wherein the primary sensing channel includes a primary band-pass filter applied to the monitored EGM signal to generate a primary filtered EGM signal compared to the primary threshold to detected R-waves.

11. The insertable cardiac monitor of claim 10 , wherein the secondary sensing channel includes a secondary band-pass filter applied to the monitored EGM signal to generate a secondary filtered EGM signal compared to the secondary threshold to detect under-sensed R-waves.

12. A non-transitory computer-readable storage medium comprising instructions that, when executed by processing circuitry, cause the processing circuitry to:

apply a primary sensing channel including a primary threshold to an electrogram (EGM) signal to detect R-waves within the EGM signal;

apply a secondary sensing channel including a secondary threshold to the EGM signal to detect under-sensed R-waves within the EGM signal;

detect at least one of bradycardia or asystole based on one or more R-waves detected by application of the primary sensing channel;

determine that the secondary sensing channel detected an under-sensed R-wave between R-waves detected by the primary sensing channel; and

determine that the detected bradycardia or asystole is false based on the detection of the under-sensed R-wave.