Method and apparatus for assessing left ventricular function and optimizing cardiac pacing intervals based on left ventricular wall motion

• US 20040172078A1
• Filed: 02/28/2003
• Published: 09/02/2004
• Est. Priority Date: 02/28/2003
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Chinchoy, Edward
• Granted Patent: US 7,610,088 B2
• Time in Patent Office: Days
• US Class Current: 607/17
• 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 1/36578 controlled by mechanical motion of the heart wall, e.g. measured by an accelerometer or microphone

Abstract

A system and method for monitoring left ventricular (LV) lateral wall motion and for optimizing cardiac pacing intervals based on left ventricular lateral wall motion is provided. The system includes an implantable or external cardiac stimulation device in association with a set of leads including a left ventricular epicardial or coronary sinus lead equipped with a motion sensor electromechanically coupled to the lateral wall of the left ventricle. The device receives and processes wall motion sensor signals to determine a signal characteristic indicative of systolic LV lateral wall motion or acceleration. An automatic pacing interval optimization method evaluates the LV lateral wall motion during varying pacing interval settings, including atrial-ventricular intervals and inter-ventricular intervals and selects the pacing interval setting(s) that correspond to LV lateral wall motion associated with improved cardiac synchrony and hemodynamic performance.

Claims

1. A method for monitoring left ventricular function, comprising:

deploying a motion sensor to a fixed location relative to a portion of a left ventricular lateral wall wherein motion the sensor generates a motion signal proportional to motion of the lateral wall;

opening a data collection window during a portion of a selected cardiac cycle phase;

storing the motion signal throughout at least a part of the portion of the data collection window for a predetermined time interval or for more than one cardiac cycle;

verifying a stability characteristic of the motion signal during the predetermined time interval or for more than one cardiac cycle;

averaging the stored motion signal; and

determining a signal characteristic from the averaged stored signal that is representative of left ventricular function.

2. A method according to claim 1, wherein said motion sensor is adapted to be disposed in a portion of the coronary sinus vessel or a blood vessel fluidly coupled to said coronary sinus.

3. A method according to claim 2, wherein said motion sensor comprises an accelerometer.

4. A method according to claim 3, wherein the accelerometer comprises a uniaxial accelerometer having a longitudinal sensing axis substantially aligned toward the left ventricular apex portion of the heart.

5. A method according to claim 2, wherein said motion sensor comprises a biaxial accelerometer.

6. A method according to claim 2, wherein said motion sensor comprises a triaxial accelerometer.

7. A method according to claim 1, wherein said motion sensor is adapted to be disposed adjacent to a portion of the epicardium of the left ventricle of the heart.

8. A method according to claim 7, wherein the portion of the epicardium is a portion of the lateral wall of the left ventricle.

9. A method according to claim 8, wherein the portion of the lateral wall is a basal portion of the lateral wall.

10. A method according to claim 9, wherein the portion of the lateral wall is a mid-basal portion of the lateral wall.

11. A method according to claim 1, wherein said motion sensor is adapted to be disposed within the pericardium of the heart.

12. A method according to claim 3, wherein the device comprises an implantable medical device.

13. A method according to claim 12, wherein the first pacing electrode or the second pacing electrode further comprises a sense electrode in electrical communication with a sensing circuit coupled to the device.

14. A computer readable medium programmed with instructions for performing a method for assessing left ventricular function and optimizing cardiac pacing intervals in a device programmed to operate a bi-ventricular cardiac pacing modality, comprising:

instructions for sensing movement of a portion of a left ventricular chamber of a heart with a deployed movement transducer and for measuring a motion signal from the transducer related to the movement;

instructions for opening a data collection window during a portion of a selected cardiac cycle phase;

instructions for storing the motion signal throughout at least a part of the portion of the data collection window for a predetermined time interval or for more than one cardiac cycle;

instructions fro verifying a stability characteristic of the motion signal during the predetermined time interval or for more than one cardiac cycle;

instructions for averaging the stored motion signal; and

instructions for determining a signal characteristic from the averaged stored signal that is representative of left ventricular function.

15. A computer readable medium according to claim 14, wherein said motion sensor is adapted to be disposed in a portion of the coronary sinus vessel or a blood vessel fluidly coupled to said coronary sinus.

16. A computer readable medium according to claim 15, wherein said motion sensor comprises an accelerometer.

17. A computer readable medium according to claim 16, wherein the accelerometer comprises a uniaxial accelerometer having a longitudinal sensing axis substantially aligned toward the left ventricular apex portion of the heart.

18. A computer readable medium according to claim 15, wherein said motion sensor comprises a biaxial accelerometer.

19. A computer readable medium according to claim 15, wherein said motion sensor comprises a triaxial accelerometer.

20. A computer readable medium according to claim 14, wherein said motion sensor is adapted to be disposed adjacent to a portion of the epicardium of the left ventricle of the heart.

21. A computer readable medium according to claim 20, wherein the portion of the epicardium is a portion of the lateral wall of the left ventricle.

22. A computer readable medium according to claim 21, wherein the portion of the lateral wall is a basal portion of the lateral wall.

23. A computer readable medium according to claim 22, wherein the portion of the lateral wall is a mid-basal portion of the lateral wall.

24. A computer readable medium according to claim 14, wherein said motion sensor is adapted to be disposed within the pericardium of the heart.

25. A computer readable medium according to claim 16, wherein the device comprises an implantable medical device.

26. A computer readable medium according to claim 25, wherein the first pacing electrode or the second pacing electrode further comprises a sense electrode in electrical communication with a sensing circuit coupled to the device and further comprising:

instructions for measuring depolarization wave activity and at least temporarily storing at least one parameter related to the measured depolarization wave activity.

37. A method according to claim 26, wherein the portion of the lateral wall is a mid-basal portion of the lateral wall.

27. A method for optimizing cardiac pacing intervals based on left ventricular function, comprising;

placing a motion sensor into electromechanical communication with a left ventricular lateral free wall so that the motion sensor generates a motion signal proportional to the motion of the lateral free wall;

enabling a temporal data collection window corresponding to a selected cardiac cycle phase;

applying a cardiac pacing stimulus delivered according to a preselected set of test pacing parameters;

sensing the motion signal during at least a part of the temporal data collection window or during a more than one cardiac cycle for at least some members of the preselected set of test pacing parameters;

verifying a heart rate stability condition;

averaging the motion signal for the at least some members of the preselected set of test pacing parameters;

determining a signal characteristic from the averaged sensed signal that is representative of relatively improved left ventricular function during each of the selected test pacing parameters; and

storing a cardiac pacing timing parameter for a right ventricular pacing electrode and for a left ventricular pacing electrode that resulted in the relatively improved left ventricular function.

28. An apparatus for optimizing left ventricular function, comprising:

means for sensing motion of a portion of the left ventricle and providing a motion signal;

means for stimulating a left ventricle and a right ventricle at the same moment and at different moments;

means for storing the sensed motion signals during a temporal window when the left ventricle and the right ventricle are stimulated at the same moment and at different moments;

means for confirming that a stability condition for the left ventricle and the right ventricle exists;

means for mathematically averaging the sensed motion signals for corresponding to when left ventricle and the right ventricle are stimulated at the same moment and at select different moments;

means for determining a signal characteristic from the averaged sensed motion signals that represents a relatively improved left ventricular function; and

means for storing a cardiac pacing timing parameter for a right ventricular pacing electrode and for a left ventricular pacing electrode that resulted in the relatively improved left ventricular function.

29. A method according to claim 28, wherein said means for sensing motion comprises a motion sensor adapted to be disposed in a portion of the coronary sinus vessel or a blood vessel fluidly coupled to said coronary sinus.

30. A method according to claim 29, wherein said motion sensor comprises an accelerometer.

31. A method according to claim 30, wherein the accelerometer comprises a uniaxial accelerometer having a longitudinal sensing axis substantially aligned toward the left ventricular apex portion of the heart.

32. A method according to claim 29, wherein said motion sensor comprises a biaxial accelerometer.

33. A method according to claim 29, wherein said motion sensor comprises a triaxial accelerometer.

34. A method according to claim 28, wherein said means for sensing motion is adapted to be disposed adjacent to a portion of the epicardium of the left ventricle of the heart.

35. A method according to claim 34, wherein the portion of the epicardium is a portion of the lateral wall of the left ventricle.

36. A method according to claim 35, wherein the portion of the lateral wall is a basal portion of the lateral wall.

38. A method according to claim 28, wherein said motion sensor is adapted to be disposed within the pericardium of the heart.

39. A method according to claim 30, wherein the device comprises an implantable medical device.

40. A method according to claim 39, wherein the first pacing electrode or the second pacing electrode further comprises a sense electrode in electrical communication with a sensing circuit coupled to the device.