Sensor response delay for hemodynamic stability detection during arrhythmia

• US 8,812,102 B2
• Filed: 05/09/2012
• Issued: 08/19/2014
• Est. Priority Date: 05/23/2011
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Li, Dan, Brisben, Amy Jean
• Primary Examiner(s): Patel, Niketa
• Assistant Examiner(s): Flory, Christopher A
• Application Number:
  US13/467,695
• Publication Number:
  US 20120303078A1
• Time in Patent Office: 832 Days
• Field of Search: 600/509, 600/515, 600/517, 600/518, 607/4, 607/5, 607/6, 607/14
• US Class Current: 607/4
• CPC Class Codes: A61B 7/00 Instruments for auscultation
• CPC Class Codes: A61N 1/36507 controlled by gradient or slope of the heart potential
• CPC Class Codes: A61N 1/36578 controlled by mechanical motion of the heart wall, e.g. measured by an accelerometer or microphone
• CPC Class Codes: A61N 1/36585 controlled by two or more physical parameters
• CPC Class Codes: A61N 1/3956 Implantable devices for applying electric shocks to the heart, e.g. for cardioversion

Abstract

An apparatus comprises a cardiac signal sensing circuit, a physiologic sensor circuit configured to provide a physiologic sensor signal representative of mechanical cardiac activity, a therapy circuit, and a control circuit. The control circuit includes a cardiac depolarization detection circuit, a tachyarrhythmia detection circuit, and a timer circuit. A time interval between a mechanical cardiac event and a detected fiducial electrical cardiac event is monitored. The control circuit is configured to correct the monitored time interval for variation with heart rate to form a corrected electromechanical time interval, initiate anti-tachyarrhythmia therapy when the corrected electromechanical time interval satisfies a specified time interval threshold value during a detected episode of tachyarrhythmia, and withhold anti-tachyarrhythmia therapy otherwise.

Claims

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.

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.

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.