Asystole detection and response in an implantable cardioverter defibrillator

Patent metadata

Field	Value
Publication number	US-10130824-B2
Application number	US-201615142074-A
Country	US
Kind code	B2
Filing date	Apr 29, 2016
Priority date	Apr 28, 2016
Publication date	Nov 20, 2018
Grant date	Nov 20, 2018

Abstract

An implantable cardioverter defibrillator (ICD) receives a cardiac electrical signal by a sensing circuit while operating in a sensing without pacing mode and detects asystole based on the cardiac electrical signal. The ICD determines, in response to detecting the asystole, if asystole backup pacing is enabled, and automatically switches to a temporary pacing mode in response to the asystole backup pacing being enabled. Other examples of detecting asystole and providing a response to detecting asystole by the ICD are described herein.

First claim

The invention claimed is:

1. An implantable cardioverter defibrillator (ICD) system, comprising:
a sensing circuit configured to receive a cardiac electrical signal via a sensing electrode vector and sense cardiac events from the cardiac electrical signal;
a therapy delivery circuit configured to deliver electrical pacing pulses to a heart of a patient via a pacing electrode vector; and
a control circuit coupled to the sensing circuit and the therapy delivery circuit and configured to automatically switch between a sensing without pacing mode and a temporary pacing mode, and further configured to:
detect asystole based on the cardiac electrical signal without delivering a pacing pulse in response to detecting the asystole while operating in the sensing without pacing mode,
in response to detecting the asystole, determine that asystole backup pacing is enabled, and
automatically switch to the temporary pacing mode in response to the asystole backup pacing being enabled.

2. The ICD system of claim 1 , wherein the control circuit is configured to remain in the sensing without pacing mode in response to the asystole backup pacing mode not being enabled.

3. The ICD system of claim 1 , further comprising:
a memory coupled to the control circuit; and
a telemetry circuit configured for bi-directional wireless communication with an external device,
wherein the control circuit is configured to
store a segment of the cardiac electrical signal in the memory in response to detecting the asystole, and
control the telemetry circuit to transmit the stored cardiac electrical signal segment to the external device.

4. The ICD system of claim 1 , further comprising a memory coupled to the control circuit,
wherein the control circuit is configured to:
set a first asystole time interval in response to an R-wave sensed by the sensing circuit;
set a second asystole time interval in response to the sensed R-wave;
enable recording of a segment of the cardiac electrical signal in the memory in response to the first asystole time interval expiring without sensing a next R-wave by the sensing circuit during the first asystole time interval; and
detect the asystole in response to the second asystole time interval expiring without sensing a next R-wave by the sensing circuit during the second asystole time interval.

5. The ICD system of claim 4 , wherein the second time interval is at least two seconds and the first time interval is shorter than the second time interval.

6. The ICD system of claim 1 , wherein the control circuit is configured to:
detect a termination condition; and
switch from the temporary pacing mode back to the sensing without pacing mode upon detection of the termination condition.

7. The ICD system of claim 6 , wherein:
the ICD further includes a telemetry circuit configured for bi-directional wireless communication with an external device; and
the control circuit is configured to detect the termination condition by detecting one of:
an expiration of a predetermined termination time interval;
a tachyarrhythmia episode;
a magnet applied over the ICD,
receipt of a termination command by the telemetry circuit,
a predetermined number of pacing pulses delivered during the temporary pacing mode, or
a predetermined number of sensed R-waves during the temporary pacing mode.

8. The ICD system of claim 1 , wherein the control circuit is configured to control the therapy delivery circuit to:
set a pacing escape interval to a first value upon switching to the temporary pacing mode;
deliver up to a predetermined number of pacing pulses at a rate corresponding to the first value when an R-wave is not sensed by the sensing circuit during the pacing escape interval set to the first value;
set the pacing escape interval to a second value longer than the first value after a last one of the predetermined number of pacing pulses is delivered at the rate corresponding to the first value; and
deliver a subsequent pacing pulse at a rate corresponding to the second value when an R-wave is not sensed during the pacing escape interval set to the second value.

9. The ICD system of claim 1 , wherein the control circuit is configured to control the therapy delivery circuit to:
set a pacing escape interval to a first value upon switching to the temporary pacing mode;
deliver up to a first predetermined number of first pacing pulses at a first rate corresponding to the first value of the pacing escape interval when an R-wave is not sensed by the sensing circuit during the pacing escape interval set to the first value;
set the pacing escape interval to a second value longer than the first value after the first predetermined number of pacing pulses are delivered at the first rate;
deliver up to a second predetermined number of second pacing pulses at a second rate corresponding to the second value of the pacing escape interval when an R-wave is not sensed during the pacing escape interval set to the second value;
set the pacing escape interval to a third value that is longer than the second value upon delivering a last one of the second predetermined number of second pacing pulses;
in response to the pacing escape interval set to the third value expiring without an R-wave sensed by the sensing circuit, deliver a third pacing pulse upon expiration of the pacing escape interval set to the third value; and
set the pacing escape interval to the second value in response to delivering the third pacing pulse.

10. The ICD system of claim 1 , wherein the control circuit is configured to:
determine at least one rest condition;
determine whether the patient is in one of a rest state or a non-rest state based on the at least one rest condition;
in response to determining the patient being in the rest state, control the therapy delivery circuit to deliver asystole backup pacing according to a first setting of a pacing control parameter; and
in response to determining the patient is in the non-rest state, control the therapy delivery circuit to deliver asystole backup pacing according to a second setting of the pacing control parameter different than the first setting.

11. The ICD system of claim 10 , wherein the ICD further comprises a sensor producing a signal correlated to at least one of patient activity or patient posture;
the control circuit being configured to determine the at least one rest condition by determining at least one of a time of day, a patient activity, or a patient posture.

12. The ICD system of claim 10 , wherein the pacing control parameter is one of a pacing escape interval, a predetermined number of pacing pulses, a pacing pulse amplitude, a hysteresis interval, or a temporary pacing mode termination condition.

13. The ICD system of claim 1 , wherein the control circuit is configured to:
detect a rest state of the patient during the sensing without pacing mode; and
in response to detecting the rest state, perform at least one of:
set an asystole detection timer to a first time interval that is longer than a second asystole detection timer used to detect asystole when a rest state is not detected; or
withhold switching to the temporary asystole backup pacing mode.

14. The ICD system of claim 1 , wherein the control circuit is configured to:
increase an asystole episode counter in response to detecting the asystole;
compare the asystole episode counter to a permanent pacing mode switch threshold;
in response to the permanent pacing mode switch threshold being reached, determine if switching to a permanent pacing mode is enabled;
switch from the sensing without pacing mode to the permanent

Assignees

• Medtronic Inc

Inventors

• Grinberg Yanina
• Sawchuk Robert T
• Thompson-Nauman Amy E
• Peterson Douglas A
• Solheim Paul R
• Lauer Joel R

Classifications

• A61N1/37258

  Alerting the patient · CPC title

• A61N1/3987 Primary

  characterised by the timing or triggering of the shock · CPC title

• A61N1/371

  Capture, i.e. successful stimulation · CPC title

• A61N1/3925

  Monitoring; Protecting · CPC title

• A61N1/3956

  Implantable devices for applying electric shocks to the heart, e.g. for cardioversion · CPC title