Sensor response delay for hemodynamic stability detection during arrhythmia

1. An apparatus comprising:

a cardiac signal sensing circuit configured to provide a cardiac signal representative of electrical cardiac activity;

a physiologic sensor circuit configured to provide a physiologic sensor signal representative of right ventricular pressure;

a therapy circuit configured to provide anti-tachyarrhythmia therapy; and

a control circuit communicatively coupled to the cardiac signal sensing circuit, the physiologic sensor circuit, and the therapy circuit, wherein the control circuit includes:

a cardiac depolarization detection circuit configured to detect a cardiac depolarization using at least one of the cardiac signal and the physiologic sensor signal;

a tachyarrhythmia detection circuit; and

a timer circuit configured to monitor an electromechanical time interval between a detected mechanical cardiac event and a detected fiducial electrical cardiac event, wherein the detected mechanical event includes peak right ventricular systolic pressure; and

wherein the control circuit is configured to:

determine a baseline for the electromechanical time interval;

normalize the monitored time interval using the determined baseline to form a corrected electromechanical time interval;

initiate anti-tachyarrhythmia therapy when the corrected electromechanical time interval satisfies a specified tachyarrhythmia detection time interval threshold value during a detected episode of tachyarrhythmia; and

withhold anti-tachyarrhythmia therapy otherwise.

2. The apparatus of claim wherein the control circuit is configure to:

establish the baseline electromechanical time interval during normal sinus (NSR); and

normalize the value of the time interval between the mechanical cardiac event and fiducial electrical cardiac event measured during the episode of tachyarrhythmia.

3. The apparatus of claim 1 ,

wherein the therapy circuit is configured to provide cardioversion/defibrillation shock therapy and anti-tachyarrhythmia pacing (ATP) therapy, and

wherein the control circuit is configured to:

initiate cardioversion/defibrillation shock therapy when detecting a change in the corrected electromechanical time interval during the episode of tachyarrhythmia that satisfies a specified tachyarrhythmia detection time interval change threshold; and

initiate anti-tachyarrhythmia pacing (ATP) therapy when detecting a change in the corrected electromechanical time interval during the episode of tachyarrhythmia that does not satisfy the specified tachyarrhythmia detection time interval change threshold.

4. The apparatus of claim 1 ,

wherein the therapy circuit is configured to provide cardioversion/defibrillation shock therapy and anti-tachyarrhythmia pacing (ATP) therapy, and

wherein the control circuit is configured to:

initiate anti-tachyarrhythmia pacing (ATP) therapy when the corrected electromechanical time interval satisfies a first tachyarrhythmia detection time interval change threshold during the episode of tachyarrhythmia; and

initiate cardioversion/defibrillation shock therapy when the corrected electromechanical time interval satisfies a second tachyarrhythmia detection time interval change threshold during the episode of tachyarrhythmia.

5. The apparatus of claim 1 , wherein the control circuit is configured to:

establish a baseline for the corrected electromechanical time interval between a mechanical cardiac event and a fiducial electrical cardiac event; and

initiate anti-tachyarrhythmia therapy when detecting, during the episode of tachyarrhythmia, a change in the corrected electromechanical time interval from the baseline time interval that satisfies a specified time interval change threshold.

6. The apparatus of claim 1 ,

wherein the timer circuit is configured to monitor the electromechanical time interval after delivery of the anti-tachyarrhythmia therapy; and

wherein the control circuit is configured to re-initiate the anti-tachyarrhythmia therapy when the corrected electromechanical time interval satisfies the same or a different time interval change threshold.

7. The apparatus of claim 1 ,

wherein the physiologic sensor circuit includes a cardiac pressure sensing circuit, and

wherein the timer circuit is configured to monitor a time interval between the detected fiducial electrical cardiac event and a detected fiducial in systolic pressure.

8. The apparatus of claim 7 , wherein the cardiac pressure sensing circuit is configured for placement in or near the right ventricle.

9. The apparatus of claim 1 ,

including a heart sound sensing circuit, and

wherein the timer circuit is further configured to monitor a time interval between the detected fiducial electrical cardiac event and a measurement of a detected heart sound.

10. The apparatus of claim 1 ,

including a cardiac impedance sensing circuit, and

wherein the timer circuit is further configured to monitor a time interval between the detected fiducial electrical cardiac event and a detected fiducial in cardiac impedance.