Method and Apparatus to Deliver Mechanically Fused Pacing Therapy

• US 20080269816A1
• 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: Prakash, Rajan, Sambelashvili, Aleksandre T.
• Granted Patent: US 7,930,027 B2
• Time in Patent Office: Days
• US Class Current: 607/9
• CPC Class Codes: A61N 1/3627 for treating a mechanical deficiency of the heart, e.g. congestive heart failure or cardiomyopathy
• CPC Class Codes: A61N 1/36542 controlled by body motion, e.g. acceleration
• CPC Class Codes: A61N 1/36564 controlled by blood pressure
• CPC Class Codes: A61N 1/36585 controlled by two or more physical parameters
• CPC Class Codes: A61N 1/3682 with a variable atrioventricular delay

Abstract

A medical device system and method for delivering mechanically fused left ventricular cardiac stimulation. A sensor monitors left ventricular acceleration while left ventricular cardiac stimulation is provided at an AV interval. The left ventricular acceleration is used to calculate a mechanical response interval and the mechanical response interval is compared to a desired mechanical response interval. The AV interval is adjusted until the mechanical response interval is equal to the desired mechanical response interval.

Claims

1. A medical device system for delivering mechanically fused left ventricular cardiac stimulation, said system comprising:

an implantable medical device (IMD);

a plurality of electrical medical leads coupled to the IMD and adapted to deliver left ventricular stimulation to a patient upon expiration of an AV interval; and

at least one sensor capable of monitoring left ventricular motion and providing a left ventricular motion signal to the IMD, the IMD determining a mechanical response interval based on the left ventricular motion signal, the IMD adjusting the AV interval after determining that the mechanical response interval differs from a predetermined desired mechanical response interval in order to deliver mechanically-fused left ventricular cardiac stimulation.

2. A medical device system according to claim 1, wherein the left ventricular motion signal comprises one of a left ventricular lateral wall acceleration signal and a derivative of the left ventricular lateral wall acceleration signal.

3. A medical device system according to claim 1, wherein the IMD determines the mechanical response interval using fiducial points on the left ventricular motion signal to detect aortic valve opening.

4. A medical device system according to claim 3, wherein the IMD determines the mechanical response interval by identifying maximum left ventricular motion during a pre-ejection interval to detect aortic valve opening.

5. A medical device system according to claim 4, wherein the maximum left ventricular motion is identified within a time window and wherein the time window is set based on one of intrinsic and evoked electrical cardiac activity.

6. A medical device system according to claim 5, wherein the mechanical response interval comprises a pre-ejection interval.

7. A medical device system according to claim 1, further comprising at least one sensor capable of monitoring a right ventricular pressure (P) coupled to said IMD.

8. A medical device system according to claim 7, wherein the IMD detects opening of a pulmonic valve by identifying a maximum right ventricular dP/dt.

9. A medical device system according to claim 8, wherein the mechanical response interval includes an interventricular delay.

10. A medical device system according to claim 1, wherein the IMD compares the mechanical response interval to the desired mechanical response interval and increases or decreases the AV interval based upon this comparison.

11. A medical device system according to claim 10, wherein the IMD increases the AV interval if the mechanical response interval is less than the desired mechanical response interval and decreases the AV interval if the mechanical response interval is greater than the desired mechanical response interval.

12. A medical device system according to claim 1, further comprising a sensor for monitoring septal wall acceleration and providing a septal wall acceleration signal to the IMD.

13. A method of providing mechanically fused left ventricular cardiac stimulation comprising:

delivering a left ventricular cardiac stimulation to a patient at an AV interval;

monitoring a left ventricular acceleration signal;

detecting an aortic valve opening using the left ventricular acceleration signal;

calculating a desired mechanical response interval;

comparing the mechanical response interval to a desired mechanical response interval; and

adjusting the AV interval until the mechanical response interval generally equals the desired mechanical response interval.

14. A method according to claim 13, wherein detecting the aortic valve opening includes identifying a maximum left ventricular acceleration within a time window.

15. A method according to claim 13, further comprising monitoring right ventricular pressure (P).

16. A method according to claim 15, further comprising detecting a opening of a pulmonic valve by identifying a maximum right ventricular dP/dt.

17. A method according to claim 13, wherein the mechanical response interval includes interventricular delay.

18. A method according to claim 17, wherein adjusting the AV interval comprises increasing the AV interval when the measured interventricular delay is less than the desired mechanical response interval, and wherein adjusting the AV interval comprises decreasing the AV interval when the measured interventricular delay is greater than the desired mechanical response interval.

19. A method of providing mechanically fused left ventricular cardiac stimulation, comprising:

delivering a left ventricular cardiac stimulation to a patient at a long AV interval;

monitoring a left ventricular acceleration signal;

monitoring right ventricular pressure (P) to produce a right ventricular P signal;

detecting a valve opening using at least one of the left ventricular acceleration signal and the right ventricular P signal;

calculating a mechanical response interval at the long AV interval based on the at least one of the left ventricular acceleration signal;

delivering a left ventricular cardiac stimulation to a patient at a short AV interval;

monitoring a left ventricular acceleration signal;

monitoring right ventricular pressure (P) to produce a right ventricular P signal;

detecting a valve opening using at least one of the left ventricular acceleration signal and the right ventricular P signal;

calculating a mechanical response interval at the short AV interval based on the at least one of the left ventricular acceleration signal;

calculating a desired mechanical response interval as a function of the mechanical response interval at the long AV interval and the mechanical response interval at the short AV interval; and

adjusting the AV interval until a measured mechanical response interval equals the desired mechanical response interval.

20. A method according to claim 19, wherein monitoring a left ventricular acceleration signal comprises monitoring a left ventricular lateral wall signal.