Heart monitoring device, system and method

• US 20040015196A1
• Filed: 03/25/2003
• Published: 01/22/2004
• Est. Priority Date: 03/25/2002
• Status: Active Grant

• Current Assignee: St. Jude Medical AB (Abbott Laboratories)
• Original Assignee: St. Jude Medical AB (Abbott Laboratories)
• Inventors: Dahlberg, Kenneth, Obel, Martin, Holmstrom, Nils, Norlin, Anna
• Granted Patent: US 7,330,758 B2
• Time in Patent Office: Days
• US Class Current: 607/17
• CPC Class Codes: A61B 5/0535 Impedance plethysmography for measuring blood flow A61B5/0295
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives
• 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 1/36521 the parameter being derived from measurement of an electrical impedance
• CPC Class Codes: A61N 1/3682 with a variable atrioventricular delay
• CPC Class Codes: A61N 1/3684 for stimulating the heart at multiple sites of the ventricle or the atrium
• CPC Class Codes: A61N 1/36842 Multi-site stimulation in the same chamber
• CPC Class Codes: A61N 1/36843 Bi-ventricular stimulation

Abstract

A heart monitoring device has a control circuit that derives an impedance value indicative of the impedance between different electrode surfaces. The control circuit determines and monitors a negative rate of change of the impedance value and determines whether the negative rate of change, or its absolute value, increases or decreases over a number of heart cycles. Alternatively or additionally, the control circuit may determine and monitor a relationship between a positive rate of change and a negative rate of change of the impedance value. The device can, in particular, be used to detect and treat a diastolic dysfunction of a heart.

Claims

1. A heart monitoring device comprising:

a control circuit having an electrical connection adapted for electrical connection to a first electrode surface at a first position of a heart and to a second electrode surface at a second position of a heart; and

said control circuit deriving an impedance value indicative of an impedance between said first and second electrode surfaces, determining a negative rate of change of said impedance value at a first portion of a heart cycle of the heart, monitoring said negative rate of change over a plurality of heart cycles of the heart, and determining whether said negative rate of change increases or decreases over said plurality of heart cycles.

2. A heart monitoring device as claimed in claim 1 wherein said control circuit determines said negative rate of change at a first point of the heart cycle of the heart cycle.

3. A heart monitoring device as claimed in claim 1 wherein said control circuit determines whether the absolute value of said negative rate of change increases or decreases over the plurality of heart cycles of the heart.

4. A heart monitoring device as claimed in claim 1 wherein said control circuit is adapted for connection to at least one electrical lead and delivers electrical stimulation pulses to a heart via said at least one electrical lead.

5. A heart monitoring device as claimed in claim 4 wherein said control circuit controls delivery of said electrical stimulation pulses dependent on said negative rate of change.

6. A heart monitoring device as claimed in claim 5 wherein said control circuit controls the delivery of said electrical stimulation pulses to control a systolic time quotient associated with a heart dependent on said negative rate of change.

7. A heart monitoring device as claimed in claim 6 wherein said control circuit increases said systolic time quotient if the absolute value of said ratio decreases.

8. A heart monitoring device as claimed in claim 6 wherein said control circuit decreases said systolic time quotient if the absolute value of said ration increases.

9. A heart monitoring device as claimed in claim 1 wherein said control circuit is adapted for connection to two electrical leads, respectively adapted to be disposed in a left ventricle and a right ventricle of a heart, and wherein said control circuit, within said cycle, delivers stimulation pulses to stimulate both of said left ventricle and said right ventricle.

10. A heart monitoring device as claimed in claim 1 further comprising a housing in which said control circuit is disposed, said housing being adapted for implantation in a living subject.

11. A heart monitoring device comprising:

a control circuit having an electrical connection adapted for electrical connection to a first electrode surface disposed at a first position of a heart and to a second electrode surface disposed at a second position of a heart; and

said control circuit deriving an impedance value indicative of an impedance between said first electrode surface and said second electrode surface, determining a negative rate of change of said impedance value at a first portion of a heart cycle, determining a positive rate of change of said impedance value at a second portion of a heart cycle, determining a relationship between said positive rate of change and said negative rate of change, and monitoring said relationship over a plurality of heart cycles.

12. A heart monitoring device as claimed in claim 11 wherein said control circuit determines said positive rate of change at a first point of a heart cycle and determines said negative rate of change at a second point of a heart cycle.

13. A heart monitoring device as claimed in claim 11 wherein said control circuit determines, as said relationship, a ratio between said positive rate of change and said negative rate of change.

14. A heart monitoring device as claimed in claim 13 wherein said control circuit determines whether said ratio increases or decreases over said plurality of heart cycles.

15. A heart monitoring device as claimed in claim 14 wherein said control circuit determines whether the absolute value of said ratio increases or decreases over said plurality of heart cycles.

16. A heart monitoring device as claimed in claim 11 wherein said control circuit is adapted for connection to at least one electrical lead and delivers electrical stimulation pulses to a heart via said at least one electrical lead.

17. A heart monitoring device as claimed in claim 16 wherein said control circuit controls delivery of said electrical stimulation pulses dependent on said relationship.

18. A heart monitoring device as claimed in claim 17 wherein said control circuit controls the delivery of said electrical stimulation pulses to control a systolic time quotient associated with a heart dependent on said relationship.

19. A heart monitoring device as claimed in claim 18 wherein said control circuit increases said systolic time quotient if the absolute value of said ratio decreases.

20. A heart monitoring device as claimed in claim 18 wherein said control circuit decreases said systolic time quotient if the absolute value of said ration increases.

21. A heart monitoring device as claimed in claim 11 wherein said control circuit is adapted for connection to two electrical leads, respectively adapted to be disposed in a left ventricle and a right ventricle of a heart, and wherein said control circuit, within said cycle, delivers stimulation pulses to stimulate both of said left ventricle and said right ventricle.

22. A heart monitoring device as claimed in claim 11 further comprising a housing in which said control circuit is disposed, said housing being adapted for implantation in a living subject.

23. A heart monitoring system comprising:

a first electrode lead having a first electrode surface adapted for placement at a first position of a heart;

a second electrode lead having a second electrode surface adapted for placement at a second position of a heart; and

a control circuit electrically connected to said first and second leads, said control circuit deriving an impedance value indicative of an impedance between said first and second electrode surfaces, determining a negative rate of change of said impedance value at a first portion of a heart cycle of the heart, monitoring said negative rate of change over a plurality of heart cycles of the heart, and determining whether said negative rate of change increases or decreases over,said plurality of heart cycles.

24. A heart monitoring system as claimed in claim 23 wherein said control circuit determines said negative rate of change at a first point of the heart cycle of the heart cycle.

25. A heart monitoring system as claimed in claim 23 wherein said control circuit determines whether the absolute value of said negative rate of change increases or decreases over the plurality of heart cycles of the heart.

26. A heart monitoring system as claimed in claim 23 wherein said control circuit is adapted for connection to at least one electrical lead and delivers electrical stimulation pulses to a heart via said at least one electrical lead.

27. A heart monitoring system as claimed in claim 26 wherein said control circuit controls delivery of said electrical stimulation pulses dependent on said negative rate of change.

28. A heart monitoring system as claimed in claim 27 wherein said control circuit controls the delivery of said electrical stimulation pulses to control a systolic time quotient associated with a heart dependent on said negative rate of change.

29. A heart monitoring system as claimed in claim 28 wherein said control circuit increases said systolic time quotient if the absolute value of said ratio decreases.

30. A heart monitoring system as claimed in claim 28 wherein said control circuit decreases said systolic time quotient if the absolute value of said ration increases.

31. A heart monitoring system as claimed in claim 23 wherein said control circuit is adapted for connection to two electrical leads, respectively adapted to be disposed in a left ventricle and a right ventricle of a heart, and wherein said control circuit, within said cycle, delivers stimulation pulses to stimulate both of said left ventricle and said right ventricle.

32. A heart monitoring system as claimed in claim 23 further comprising a housing in which said control circuit is disposed, said housing being adapted for implantation in a living subject.

52. A method as claimed in claim 25 wherein step (d) comprises determining a negative rate of change of said impedance value at a first point of said heart cycle and wherein step (e) comprises determining a positive rate of change of said impedance value at a second point of said heart cycle.

53. A method as claimed in claim 52 wherein steps (a) and (b) comprise positioning said first and second electrode surfaces to measure said impedance value across at least a part of a ventricle of said heart.

54. A method as claimed in claim 53 comprising measuring said impedance value across the left ventricle of the heart.

55. A method as claimed in claim 52 comprising using said relationship to monitor systolic dysfunction of the heart.

56. A method as claimed in claim 55 wherein steps (a) and (b) comprise placing said first and second electrodes in a heart of a patient suffering from congestive heart failure, and monitoring said systolic dysfunction as a symptom of said congestive heart failure.

57. A method as claimed in claim 56 comprising delivering electrical stimulation pulses to the heart to control a systolic time quotient of the heart.

58. A method as claimed in claim 57 comprising delivering said stimulation pulses to each of the left ventricle and the right ventricle of the heart.

33. A heart monitoring system comprising:

a first electrode lead having a first electrode surface adapted for placement at a first position of a heart;

a second electrode lead having a second electrode surface adapted for placement at a second position of a heart; and

a control circuit electrically connected to said first and second leads, said control circuit deriving an impedance value indicative of an impedance between said first electrode surface and said second electrode surface, determining a negative rate of change of said impedance value at a first portion of a heart cycle, determining a positive rate of change of said impedance value at a second portion of a heart cycle, determining a relationship between said positive rate of change and said negative rate of change, and monitoring said relationship over a plurality of heart cycles.

34. A heart monitoring system as claimed in claim 33 wherein said control circuit determines said positive rate of change at a first point of a heart cycle and determines said negative rate of change at a second point of a heart cycle.

35. A heart monitoring system as claimed in claim 33 wherein said control circuit determines, as said relationship, a ratio between said positive rate of change and said negative rate of change.

36. A heart monitoring system as claimed in claim 35 wherein said control circuit determines whether said ratio increases or decreases over said plurality of heart cycles.

37. A heart monitoring system as claimed in claim 36 wherein said control circuit determines whether the absolute value of said ratio increases or decreases over said plurality of heart cycles.

38. A heart monitoring system as claimed in claim 33 wherein said control circuit is adapted for connection to at least one electrical lead and delivers electrical stimulation pulses to a heart via said at least one electrical lead.

39. A heart monitoring system as claimed in claim 38 wherein said control circuit controls delivery of said electrical stimulation pulses dependent on said relationship.

40. A heart monitoring system as claimed in claim 39 wherein said control circuit controls the delivery of said electrical stimulation pulses to control a systolic time quotient associated with a heart dependent on said relationship.

41. A heart monitoring system as claimed in claim 40 wherein said control circuit increases said systolic time quotient if the absolute value of said ratio decreases.

42. A heart monitoring system as claimed in claim 40 wherein said control circuit decreases said systolic time quotient if the absolute value of said ration increases.

43. A heart monitoring system as claimed in claim 33 wherein said control circuit is adapted for connection to two electrical leads, respectively adapted to be disposed in a left ventricle and a right ventricle of a heart, and wherein said control circuit, within said cycle, delivers stimulation pulses to stimulate both of said left ventricle and said right ventricle.

44. A heart monitoring system as claimed in claim 33 further comprising a housing in which said control circuit is disposed, said housing being adapted for implantation in a living subject.

45. A method for monitoring a heart comprising the steps of:

(a) placing a first electrode surface at a first position of a heart;

(b) placing a second electrode surface at a second position of the heart;

(c) deriving an impedance value indicative of an impedance between said first and second electrode surfaces;

(d) determining a negative rate of change of said impedance value at a first portion of a heart cycle of the heart;

(e) monitoring said negative rate of change over a plurality of heart cycles of the heart; and

(f) determining whether said negative rate of change increases or decreases over said plurality of heart cycles of the heart.

46. A method as claimed in claim 45 wherein steps (a) and (b) comprise positioning said first and second electrode surfaces to measure said impedance value across at least a part of a ventricle of said heart.

47. A method as claimed in claim 46 comprising measuring said impedance value across the left ventricle of the heart.

48. A method as claimed in claim 45 comprising using said relationship to monitor systolic dysfunction of the heart.

49. A method as claimed in claim 48 wherein steps (a) and (b) comprise placing said first and second electrodes in a heart of a patient suffering from congestive heart failure, and monitoring said systolic dysfunction as a symptom of said congestive heart failure.

50. A method as claimed in claim 48 comprising delivering electrical stimulation pulses to the heart to control a systolic time quotient of the heart.

51. A method as claimed in claim 50 comprising delivering said stimulation pulses to each of the left ventricle and the right ventricle of the heart.