Method and Apparatus for Sensing Improvement Using Pressure Data

• US 20080269627A1
• Filed: 04/30/2007
• Published: 10/30/2008
• Est. Priority Date: 04/30/2007
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Kleckner, Karen J., Gordon, Charles R., Davie, Scott W., Whitman, Teresa A., Cho, Yong K., Brown, Mark L.
• Granted Patent: US 7,890,162 B2
• Time in Patent Office: Days
• US Class Current: 600/521
• CPC Class Codes: A61B 5/318 Heart-related electrical modalities, e.g. electrocardiography [ECG]
• CPC Class Codes: A61B 5/33 specially adapted for cooperation with other devices
• CPC Class Codes: A61B 5/349 Detecting specific parameters of the electrocardiograph cycle
• CPC Class Codes: A61B 5/6846 specially adapted to be brought in contact with an internal body part, i.e. invasive
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal
• CPC Class Codes: A61N 1/36585 controlled by two or more physical parameters
• CPC Class Codes: A61N 1/3962 in combination with another heart therapy
• CPC Class Codes: A61N 1/39622 Pacing therapy

Abstract

Method and apparatus for sensing improvement using pressure data. The method and apparatus may be used in an implantable medical device to confirm that an EGM event signifies a true mechanical cardiac activity and not just electrical oversensing. The mechanical activity may be used to create a mechanical marker channel in the implantable medical device.

Claims

1. A method of confirming that an EGM deflection represents an R-wave comprising:

sensing an EGM via an implantable medical device (IMD);

sensing an intracardiac pressure via the IMD;

determining a dP/dt of the sensed intracardiac pressure;

detecting an electrical event using the EGM;

opening a time window after detecting the electrical event;

determining a maximum positive dP/dt of the intracardiac pressure sensed during the open time window; and

detecting the presence of a mechanical event using the maximum positive dP/dt, the mechanical event being deemed present when the maximum positive dP/dt is greater than a first threshold, and the presence of the mechanical event indicating that the electrical event includes an R-wave.

2. A method according to claim 1, wherein the mechanical event is deemed absent when the maximum positive dP/dt does not exceed the first threshold.

3. A method according to claim 2, further comprising:

determining a minimum dP/dt of the intracardiac pressure sensed during the open time window; and

detecting the presence of an oversensed T-wave or noise using the minimum negative dP/dt, the oversensed T-wave or noise being deemed present when mechanical event is deemed absent and an absolute value of the minimum negative dP/dt is greater than a second threshold.

4. A method according to claim 3, further comprising withholding defibrillation when the EGM indicates a tachyarrhythmia and the oversensed T-wave or noise is deemed present.

5. A method according to claim 2, further comprising:

determining a minimum dP/dt of the intracardiac pressure sensed during the open time window;

detecting the presence of an R-wave with no corresponding mechanical event, the R-wave without a corresponding mechanical event being deemed present when the mechanical event is deemed absent and an absolute value of the minimum dP/dt is not greater than a second threshold.

6. A method according to claim 1, wherein the time window is between approximately 400 and approximately 500 milliseconds or equal to the duration between two sequentially detected R-waves, which ever is smallest.

7. A method according to claim 1, wherein the first threshold is approximately 100 mmHg/s.

8. A method according to claim 1, wherein the presence of the mechanical event is recorded by the device on a marker channel.

9. A method according to claim 1, wherein the intracardiac pressure is right ventricular pressure.

10. A method of confirming that an implantable medical device (IMD) is not oversensing electrical activity in an EGM, comprising:

sensing an EGM via an implantable medical device;

detecting electrical events using the EGM;

sensing an intracardiac pressure via the IMD;

determining a dP/dt of the sensed intracardiac pressure;

detecting the presence of a mechanical event using the dP/dt, a mechanical event being deemed present when the dP/dt exceeds a threshold, the electrical events and mechanical events being detected independently from each other; and

comparing the electrical events to the mechanical events to identify which electrical events are followed by and associated with mechanical events, the identification of associated electrical and mechanical events indicating that such electrical events have not been oversensed.

11. A method according to claim 10, wherein mechanical events occurring between a first electrical event and a subsequent electrical event are deemed to be associated with the first electrical event.

12. A method according to claim 10, wherein the intracardiac pressure and the EGM are right ventricular and wherein the electrical events followed by and associated with mechanical events include an R-wave.

13. A method according to claim 12, further including identifying which electrical events are not followed by or associated with mechanical events, such electrical events indicating T-wave oversensing or noise.

14. A method according to claim 10, further comprising withholding defibrillation when the EMG indicates a tachyarrhythmia but the oversensed T-waves or noise is indicated.

15. A method according to claim 10, wherein the intracardiac pressure and the EGM are right atrial.

16. A method according to claim 15, wherein the electrical events not followed by and associated with mechanical events indicate far field R wave oversensing.

17. A computer-readable medium programmed with instructions for operating an implantable medical device, the medium comprising instructions for causing a programmable processor to:

receive sensed intracardiac pressure;

identify mechanical events using the sensed intracardiac pressure; and

store the mechanical events as a mechanical sense channel.

18. A computer-readable medium of claim 17, further comprising instructions to ignore mechanical events occurring within a threshold time period after another mechanical event.

19. A computer-readable medium of claim 17, further comprising instructions to provide cardiac stimulation when mechanical events occur within a threshold time period after another mechanical event, the mechanical events indicating an arrhythmia.

20. A computer-readable medium of claim 17, further comprising instructions to determine a dP/dt of the sensed intracardiac pressure, the mechanical events being identified based on the dP/dt.