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

• US 10,413,207 B2
• Filed: 03/25/2016
• Issued: 09/17/2019
• Est. Priority Date: 03/25/2016
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Sarkar, Shantanu, Hudziak, Michael, Reiland, Jerry, Reisfeld, Erin
• Primary Examiner(s): Layno, Carl H
• Assistant Examiner(s): Piateski, Erin M
• Application Number:
  US15/081,216
• Publication Number:
  US 20170273589A1
• Time in Patent Office: 1,271 Days
• Field of Search: 600509, 600515
• CPC Class Codes: A61B 2505/07 Home care
• CPC Class Codes: A61B 2560/0468 Built-in electrodes
• CPC Class Codes: A61B 5/287 Holders for multiple electrodes, e.g. electrode catheters for electrophysiological study [EPS]
• CPC Class Codes: A61B 5/316 Modalities, i.e. specific diagnostic methods
• CPC Class Codes: A61B 5/335 using integrated circuit memory devices
• CPC Class Codes: A61B 5/352 Detecting R peaks, e.g. for synchronising diagnostic apparatus; Estimating R-R interval
• CPC Class Codes: A61B 5/363 Detecting tachycardia or bradycardia
• CPC Class Codes: A61B 5/364 Detecting abnormal ECG interval, e.g. extrasystoles, ectopic heartbeats
• CPC Class Codes: A61B 5/6861 Capsules, e.g. for swallowing or implanting
• CPC Class Codes: A61B 5/7221 Determining signal validity, reliability or quality A61B5/7207 and A61B5/7217 take precedence
• CPC Class Codes: A61N 1/36514 controlled by a physiological quantity other than heart potential, e.g. blood pressure controlled by two or more physical parameters A61N1/36585
• CPC Class Codes: A61N 1/3956 Implantable devices for applying electric shocks to the heart, e.g. for cardioversion
• CPC Class Codes: A61N 1/3987 characterised by the timing or triggering of the shock

Abstract

A system and method for detecting and verifying bradycardia/asystole episodes includes sensing an electrogram (EGM) signal. The EGM signal is compared to a primary threshold to sense events in the EGM signal, and at least one of a bradycardia or an asystole is detected based on the comparison. In response to detecting at least one of a bradycardia or an asystole, the EGM signal is compared to a secondary threshold to sense events under-sensed by the primary threshold. The validity of the bradycardia or the asystole is determined based on the detected under-sensed events.

Claims

1. A method comprising:

sensing an electrogram (EGM) signal;

comparing an amplitude of the EGM signal to a primary threshold using circuitry to directly sense R-waves in the EGM signal;

detecting at least one of a bradycardia or an asystole based on the sensed R-waves;

in response to detecting at least one of a bradycardia or an asystole, comparing the amplitude of the EGM signal utilized to detect the bradycardia or asystole to a secondary threshold using circuitry to directly sense R-waves under-sensed by the primary threshold; and

determining whether the detection of the bradycardia or the asystole is false based on the detection of under-sensed R-waves.

2. The method of claim 1, wherein the primary threshold is an auto-adjusted threshold and the secondary threshold is an auto-adjusted threshold.

3. The method of claim 2, wherein the secondary auto-adjusting threshold decays to a minimum value more quickly than the primary auto-adjusting threshold.

4. The method of claim 2, wherein the secondary auto-adjusting threshold is initialized to a maximum value following a sense R-wave, wherein the maximum value is a function of an amplitude of the 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.

5. The method of claim 2, further including:

filtering and rectifying the sensed EGM signal in a primary sense channel and applying the primary auto-adjust threshold to the filtered/rectified EGM signal; and

applying the secondary auto-adjust threshold to the filtered/rectified EGM signal.

6. The method of claim 2, further including:

filtering and rectifying the sensed EGM signal in a primary sense channel to generate a primary filtered/rectified EGM signal, wherein the primary auto-adjust threshold is applied to the primary filtered/rectified EGM signal; and

filtering and rectifying the sensed EGM signal in a secondary sense channel to generate a secondary filtered/rectified EGM signal, wherein the secondary auto-adjust threshold is applied to the secondary filtered/rectified EGM signal, wherein filtering in the secondary sense channel selects lower frequency components than filtering in the primary sense channel.

7. The method of claim 1, further including:

starting a timer in response to a detected asystole;

resetting the timer in response to detection of an under-sensed R-wave via application of the secondary threshold; and

determining whether the detected asystole is false based on the value of the timer following the asystole.

8. The method of claim 7, wherein the timer is started in response to at least one of a sensed R-wave or escape beat that marks a beginning of the detected asystole.

9. A method comprising:

sensing an electrogram (EGM) signal;

comparing using a primary sense channel circuitry an amplitude of the EGM signal to a primary threshold to directly sense R-waves in the EGM signal and generating a primary sensed R wave output;

comparing using a secondary sense channel circuitry the amplitude of the EGM signal to a secondary threshold to directly sense R-waves under-sensed by the primary threshold and generating a secondary sensed R-wave output;

detecting at least one of a bradycardia or an asystole based on the primary sensed R-waves output; and

verifying whether the detected bradycardia/asystole is true/false based on the secondary sensed R-wave output generated by the secondary sense channel.

10. The method of claim 9, 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.

11. The method of claim 10, wherein the secondary auto-adjusting threshold is initialized to a maximum value following a sense R-wave, wherein the maximum value is a function of an amplitude of the 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.