Apparatus and method for setting the parameters of an alert window used for timing the delivery of ETC signals to a heart under varying cardiac conditions

• US 6,233,487 B1
• Filed: 06/23/1999
• Issued: 05/15/2001
• Est. Priority Date: 06/08/1999
• Status: Expired due to Term

• Current Assignee: Impulse Dynamics NV
• Original Assignee: Impulse Dynamics NV
• Inventors: Mika, Yuval, Belsky, Ziv, Prutchi, David, Routh, Andre G.
• Primary Examiner(s): Jastrzab, Jeffrey R.
• Application Number:
  US09/338,649
• Time in Patent Office: 692 Days
• Field of Search: 607/9, 607/17, 607/18, 607/25, 607/27, 600/510, 600/521
• US Class Current: 607/27
• CPC Class Codes: A61B 5/318 Heart-related electrical modalities, e.g. electrocardiography [ECG]
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal
• CPC Class Codes: A61N 1/3622 comprising two or more electrodes co-operating with different heart regions
• CPC Class Codes: A61N 1/3627 for treating a mechanical deficiency of the heart, e.g. congestive heart failure or cardiomyopathy
• CPC Class Codes: H01L 21/568 Temporary substrate used as encapsulation process aid H01L21/4832 and H01L21/566 take precedence
• CPC Class Codes: H01L 21/6835 using temporarily an auxiliary support
• CPC Class Codes: H01L 23/3107 the device being completely enclosed
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Abstract

A method for setting the parameters of an alert time window in an excitable tissue control device operative under a plurality of different cardiac conditions of a heart of a patient. The method includes providing said excitable tissue control device with a set of data including a plurality of sets of alert time window parameters. Each set of window parameters is uniquely associated with a different set of values of a plurality of cardiac condition defining parameters identifying one of the different cardiac conditions. Each set of window parameters includes at least a set of timing parameters usable for obtaining a beginning time point and an ending time point of the alert window. The sets of window parameters are obtained by processing data collected within a data collection session from a plurality of cardiac beats of the same patient under the different cardiac conditions. The methods updates for each current beat cycle the values of a plurality of cardiac condition defining variables corresponding to said cardiac condition defining parameters, automatically selects a current set of alert time window parameters based on the current values of the cardiac condition defining variables, starts and terminates the alert time window based on the time of detecting a first depolarization event at a first cardiac site, detects within the duration of the alert window a second depolarization event at a second cardiac site, and triggers the delivery of a delayed non-excitatory excitable tissue control signal at the second cardiac site based on the time of detection of the second depolarization event. The different cardiac conditions include different beat cycle lengths, and may include beats which are or are not influenced by prior application of ETC signals to the heart and, where relevant, naturally and artificially paced beats. The alert window parameters may include an event detection sensitivity level parameter. Implantable and external devices are describe which are adapted for implementing the disclosed method.

Claims

1. A method for setting the parameters of an alert time window in an excitable tissue control device operative under a plurality of different cardiac conditions of a heart of a patient, the method comprising the steps of:

providing said excitable tissue control device with a set of data, said set of data comprises a plurality of sets of alert time window parameters, each set of alert time window parameters of said plurality of sets of alert time window parameters is associated with one of said plurality of different cardiac conditions, each set of alert time window parameters of said plurality of sets of alert time window parameters comprises at least a set of timing parameters usable for obtaining a beginning time point and an ending time point for said alert time window, each set of alert time window parameters of said plurality of sets of alert time window parameters is obtained by processing data collected from a plurality of cardiac beats of said heart of said patient under said plurality of different cardiac conditions within a data collection session prior to said step of providing;

automatically selecting, for a current beat cycle of said heart, a current set of alert time window parameters of said plurality of sets of alert time window parameters based on the current cardiac conditions detected for said current beat cycle;

using, for said current beat cycle, said current set of alert time window parameters selected in said step of automatically selecting to start and terminate said alert time window based on the time of detecting a first depolarization event at or about a first cardiac site;

detecting within the duration of said alert time window of said current beat cycle a second depolarization event at a second cardiac site of said heart; and

triggering the delivery of a delayed non-excitatory excitable tissue control signal at or about said second cardiac site based on the time of detection of said second depolarization event.

2. The method according to claim 1 wherein each set of alert time window parameters of said plurality of sets of alert time window parameters further comprises at least one detection sensitivity parameter having a value representing a detection sensitivity level, and wherein said step of using further includes using said value of said detection sensitivity parameter to set the detection sensitivity level used within the duration of said alert time window of said current beat cycle.

3. The method according to claim 2 wherein said at least one detection sensitivity parameter comprises a voltage threshold level.

4. The method according to claim 2 wherein said at least one detection sensitivity parameter comprises at least one morphological detection parameter.

5. The method according to claim 2 wherein said set of data is a degenerate set of data in which at least some of said sets of alert time window parameters of said plurality of sets of alert time window parameters have identical values of said at least one detection sensitivity parameter.

6. The method according to claim 1 wherein said plurality of cardiac conditions comprises beats having a plurality of different beat to beat time intervals representing different instantaneous heart rates of said heart.

7. The method according to claim 1 wherein said plurality of cardiac conditions further comprises beats initiated by the natural pacemaker of said heart and beats initiated by a pacing pulse delivered by said excitable tissue control device.

8. The method according to claim 1 wherein said plurality of cardiac conditions comprises beats occurring during a time period in which the prior application of excitable tissue control signals results in a change of the velocity of propagation of a depolarization wave in at least a portion of the myocardial tissue disposed between said first cardiac site and said second cardiac site of said heart, and beats occurring during a time period in which the prior application of excitable tissue control signals does not result in a change in the velocity of propagation of a depolarization wave in a portion of the myocardial tissue disposed between said first cardiac site and said second cardiac site of said heart.

9. The method according to claim 1 wherein said set of timing parameters of said alert time window parameters comprises a beginning time point value and an ending time point value for said alert time window.

10. The method according to claim 1 wherein said excitable tissue control device is provided with a value of the bin duration of a time bin used for collecting data within said data collection session, said set of timing parameters of said alert time window parameters comprises a starting bin number and an ending bin number and wherein said step of using includes computing the starting time point and ending time point of said alert time window from said bin duration, said starting bin number and said ending bin number, prior to said starting of said alert time window.

11. The method according to claim 1 wherein said set of timing parameters comprises a set of approximation parameters and wherein said processing of said step of providing comprises using an approximation method to process said data collected from said heart in said data collection session to obtain a plurality of sets of approximation parameters, usable for computing improved approximated values of the beginning time point and the ending time point of said alert time window.

12. The method according to claim 11 wherein said approximation method is a linear piecewise approximation method, said set of approximation parameters comprises a beginning time point parameter and a first slope parameter associated with said beginning time point parameter, an ending time point parameter and a second slope parameter associated with said ending time point parameter, and wherein said step of using comprises computing an approximated beginning time point for said alert time window of said current beat cycle from the values of the current cycle length measured for said current beat cycle, said first slope parameter and said beginning time point parameter, and computing an approximated ending time point for said alert time window of said current beat cycle from the values of said current cycle length, said second slope parameter and said ending time point parameter.

13. The method according to claim 12 wherein said current cycle length is the instantaneous cycle length determined from the current R—

R interval or the current A—

A interval measured for said current beat cycle.

14. The method according to claim 12 wherein said current cycle length is an average cycle length computed from the values of a plurality of consecutive R—

R intervals including the R—

R interval of said current beat cycle.

15. The method according to claim 12 wherein said current cycle length is an average cycle length computed from the values of a plurality of consecutive A—

A intervals including the A—

A interval of said current beat cycle.

16. The method according to claim 1 wherein said set of timing parameters comprises said beginning time point and said ending time point of said alert time window.

17. The method according to claim 1 wherein said set of data is a degenerate set of data in which at least some of said sets of alert time window parameters of said plurality of sets of alert time window parameters have identical values of said set of timing parameters.

18. The method according to claim 1 wherein said first cardiac site is the right ventricle of said heart and said second cardiac site is the left ventricle of said heart.

19. The method according to claim 1 wherein said first cardiac site is the right atrium of said heart and said second cardiac site is the left ventricle of said heart.

20. A method for setting the parameters of an alert time window in an excitable tissue control device operative under a plurality of different cardiac conditions of a heart of a patient, the method comprising the steps of:

providing said excitable tissue control device with a set of data, said set of data comprises a plurality of sets of alert time window parameters, each set of alert time window parameters is uniquely associated with a different set of values of a plurality of cardiac condition defining parameters identifying one of said plurality of different cardiac conditions, each set of alert time window parameters of said plurality of sets of alert time window parameters comprises at least a set of timing parameters usable for obtaining a beginning time point and an ending time point for said alert time window, each set of alert time window parameters of said plurality of sets of alert time window parameters is obtained by processing data collected from a plurality of cardiac beats of said heart of said patient under said plurality of different cardiac conditions within a data collection session prior to said step of providing;

updating for a current beat cycle of said heart the values of a plurality of cardiac condition defining variables corresponding to said cardiac condition defining parameters;

automatically selecting for said current beat cycle a current set of alert time window parameters of said plurality of sets of alert time window parameters based on the current values of said cardiac condition defining variables;

using, for said current beat cycle, said current set of alert time window parameters selected in said step of automatically selecting to start and terminate said alert time window based on the time of detecting a first depolarization event at or about a first cardiac site;

detecting within the duration of said alert time window of said current beat cycle a second depolarization event at a second cardiac site of said heart; and

triggering the delivery of a delayed non-excitatory excitable tissue control signal at or about said second cardiac site based on the time of detection of said second depolarization event.

21. The method according to claim 20 wherein each set of alert time window parameters of said plurality of sets of alert time window parameters further comprises at least one detection sensitivity parameter having a value representing a detection sensitivity level, and wherein said step of using further includes using said value of said detection sensitivity parameter to set the detection sensitivity level of said excitable tissue control device for said current beat cycle.

22. The method according to claim 21 wherein said at least one detection sensitivity parameter comprises a voltage threshold level.

23. The method according to claim 21 wherein said at least one detection sensitivity parameter comprises at least one morphological detection parameter.

24. The method according to claim 21 wherein said set of data is a degenerate set of data in which at least some of said sets of alert time window parameters of said plurality of sets of alert time window parameters have identical values of said at least one detection sensitivity parameter.

25. The method according to claim 20 wherein said plurality of cardiac condition defining parameters comprises a cycle length category parameter, said cycle length category parameter has a value selected from a plurality of preset values each one of said plurality of preset values represents a different range of beat cycle lengths, one of said plurality of cardiac condition defining variables is a cycle length category variable, and wherein said step of updating includes updating the value of said cycle length category variable by determining the cycle length range into which the current measured beat to beat time interval falls and by setting as the value of said cycle length category variable one of said plurality of preset values corresponding with said cycle length range.

26. The method according to claim 20 wherein said plurality of cardiac conditions comprises beats initiated by the natural pacemaker of said heart and beats initiated by a pacing pulse delivered by said excitable tissue control device, one of said plurality of cardiac condition defining parameters is a parameter which may have a first value defining beats initiated by the natural pacemaker of said heart or a second value defining beats initiated by a pacing pulse delivered by said excitable tissue control device, and wherein one of said plurality of cardiac condition defining variables is a variable which may have the said first value defining a current beat initiated by the natural pacemaker of said heart or the said second value defining a current beat initiated by a pacing pulse delivered by said excitable tissue control device.

27. The method according to claim 20 wherein said plurality of cardiac conditions further comprises beats occurring during a time period in which the prior application of excitable tissue control signals results in a change of the velocity of propagation of a depolarization wave in at least a portion of the myocardial tissue disposed between said first cardiac site and said second cardiac site of said heart, and beats occurring during a time period in which the prior application of excitable tissue control signals does not result in a change in the velocity of propagation of a depolarization wave in said portion of the myocardial tissue disposed between said first cardiac site and said second cardiac site of said heart.

28. The method according to claim 20 wherein said set of timing parameters of said alert time window parameters comprises a beginning time point value and an ending time point value for an alert time window.

29. The method according to claim 20 wherein said excitable tissue control device is provided with a value of the bin duration of a time bin used for collecting data within said data collection session, said set of timing parameters of said alert time window parameters comprises a starting bin number and an ending bin number and wherein said step of using includes computing the starting time point and ending time point of said alert time window from said bin duration, said starting bin number and said ending bin number prior to said starting of said alert time window.

30. The method according to claim 20 wherein said set of timing parameters comprises a set of approximation parameters and wherein said processing of said step of providing comprises using an approximation method to process said data collected from said heart in said data collection session to obtain a plurality of sets of approximation parameters, usable for computing improved approximated values of the beginning time point and the ending time point of said alert time window.

31. The method according to claim 30 wherein said approximation method is a linear piecewise approximation method, said set of approximation parameters comprises a beginning time point parameter and a first slope parameter associated with said beginning time point parameter, an ending time point parameter and a second slope parameter associated with said ending time point parameter, and wherein said step of using comprises computing an approximated beginning time point for said alert time window of said current beat cycle from the values of the current cycle length, said first slope parameter and said beginning time point parameter, and computing an approximated ending time point for said alert time window of said current beat cycle from the values of said current cycle length, said second slope parameter and said ending time point parameter.

32. The method according to claim 31 wherein said current cycle length is the instantaneous cycle length determined from the current R—

R interval or the current A—

A interval measured for said current beat cycle.

33. The method according to claim 31 wherein said current cycle length is an average cycle length computed from the values of a plurality of consecutive R—

R intervals including the R—

R interval of said current beat cycle.

34. The method according to claim 31 wherein said current cycle length is an average cycle length computed from the values of a plurality of consecutive A—

A intervals including the A—

A interval of said current beat cycle.

35. The method according to claim 20 wherein said set of timing parameters comprises said beginning time point and said ending time point of said alert time window.

36. The method according to claim 20 wherein said set of data is a degenerate set of data in which the values of said set of timing parameters of at least some of the sets of said plurality of sets of alert time window parameters are identical.

37. The method according to claim 20 wherein said first cardiac site is the right ventricle of said heart and said second cardiac site is the left ventricle of said heart.

38. The method according to claim 20 wherein said first cardiac site is the right atrium of said heart and said second cardiac site is the left ventricle of said heart.

39. An excitable tissue control device for setting on a beat by beat basis the parameters of an alert time window under a plurality of different cardiac conditions of a heart of a patient, the device comprising:

a plurality of electrodes adapted to be implanted in or about said heart;

detection circuitry for detecting electrical depolarization events in a first cardiac site through at least a first electrode of said plurality of electrodes, said at least first electrode is disposed in or about said first cardiac site, and for detecting electrical depolarization events in a second cardiac site through at least a second electrode of said plurality of electrodes, said at least second electrode is disposed in or about said second cardiac site;

an excitable tissue control unit for delivering non-excitatory excitable tissue control signals to at least part of said second cardiac site through one or more electrodes of said plurality of electrodes;

a memory unit for storing a set of data, said set of data comprises a plurality of sets of alert time window parameters, each set of alert time window parameters is uniquely associated with a different set of values of a plurality of cardiac condition defining parameters identifying one of said plurality of different cardiac conditions, each set of alert time window parameters comprises at least a set of timing parameters usable for obtaining a beginning time point and an ending time point for said alert time window, each set of alert time window parameters is obtained by processing data collected from a plurality of cardiac beats of said heart of said patient under said plurality of different cardiac conditions within a data collection session performed in said patient;

a processor unit operatively connected to said detection circuitry, said excitable tissue control unit and said memory unit, for receiving detection signals from said detection circuitry, for controlling said excitable tissue control unit by using the received detection signals, for updating in a current beat cycle of said heart the values of a plurality of cardiac condition defining variables corresponding to said cardiac condition defining parameters, for automatically selecting for said current beat cycle a current set of alert time window parameters of said plurality of sets of alert time window parameters based on the current values of said cardiac condition defining variables, for applying said current set of alert time window parameters to start said alert time window within said current beat cycle after detecting a first depolarization event at or about said first cardiac site and to terminate said alert time window, and for initiating the delivery of a delayed excitable tissue control signal at or about said second cardiac site upon detecting within the duration of said alert time window a depolarization event in or about said second cardiac site of said heart; and

a power source for providing power to said detection circuitry, said processor unit said memory unit and said excitable tissue control unit.

40. The device according to claim 39 further including a telemetry unit operatively connected to said power source and said processor unit for telemetrically receiving data from a second telemetry unit disposed outside said patient.

41. The device according to claim 39 wherein said plurality of sets of alert time window parameters of said set of data are stored in said memory unit as a data array or a look up table.

42. The device according to claim 39 wherein said detection circuitry is adapted for being controllably switched between a plurality of detection sensitivity levels, and wherein each set of alert time window parameters of said plurality of sets of alert time window parameters further comprises at least one detection sensitivity parameter having a value representing one of said plurality of detection sensitivity levels of said detection circuitry, and wherein said processor unit is adapted for using said value of said at least one detection sensitivity parameter of said current beat cycle to switch said detection circuitry to a detection sensitivity level represented by said at least one detection sensitivity parameter of said current beat cycle.

43. The device according to claim 42 wherein said detection circuitry is adapted for being switched between a plurality of voltage threshold levels and said at least one detection sensitivity parameter comprises a voltage threshold level.

44. The device according to claim 42 wherein said detection circuitry is adapted for performing event detection based on a morphological detection method and wherein said at least one detection sensitivity parameter comprises at least one morphological detection parameter.

45. The device according to claim 40 wherein said set of data is a degenerate set of data in which at least some of said sets of alert time window parameters of said plurality of sets of alert time window parameters have identical values of said at least one detection sensitivity parameter.

46. The device according to claim 39 wherein said plurality of cardiac conditions comprises beats having a plurality of different beat to beat time intervals representing different instantaneous heart rates of said heart.

47. The device according to claim 46 wherein said plurality of cardiac conditions further comprises beats occurring during a time period in which the prior application of excitable tissue control signals results in a change of the velocity of propagation of a depolarization wave in at least a portion of the myocardial tissue disposed between said first cardiac site and said second cardiac site of said heart, and beats occurring during a time period in which the prior application of excitable tissue control signals does not result in a change in the velocity of propagation of a depolarization wave in at least a portion of the myocardial tissue disposed between said first cardiac site and said second cardiac site of said heart.

48. The device according to claim 39 wherein said plurality of cardiac conditions comprises beats occurring during a time period in which the prior application of excitable tissue control signals results in a change of the velocity of propagation of a depolarization wave in at least a portion of the myocardial tissue disposed between said first cardiac site and said second cardiac site of said heart, and beats occurring during a time period in which the prior application of excitable tissue control signals does not result in a change in the velocity of propagation of a depolarization wave in at least a portion of the myocardial tissue disposed between said first cardiac site and said second cardiac site of said heart.

49. The device according to claim 39 further including a pacing unit operatively connected to said power source, said processor unit and to at least one electrode of said plurality of electrodes for delivering pacing pulses to said heart through said at least one electrode.

50. The device according to claim 49 wherein said plurality of cardiac conditions comprises beats initiated by the natural pacemaker of said heart and beats initiated by a pacing pulse delivered by said excitable tissue control device.

51. The device according to claim 50 wherein said plurality of cardiac conditions further comprise beats having a plurality of different beat to beat time intervals representing different instantaneous heart rates of said heart.

52. The device according to claim 51 wherein said plurality of cardiac conditions further comprises beats occurring during a time period in which the prior application of excitable tissue control signals results in a change of the velocity of propagation of a depolarization wave in at least a portion of the myocardial tissue disposed between said first cardiac site and said second cardiac site of said heart, and beats occurring during a time period in which the prior application of excitable tissue control signals does not result in a change in the velocity of propagation of a depolarization wave in at least a portion of the myocardial tissue disposed between said first cardiac site and said second cardiac site of said heart.

53. The device according to claim 39 wherein said set of timing parameters of said alert time window parameters comprises a beginning time point value and an ending time point value for said alert time window.

54. The device according to claim 39 wherein said excitable tissue control device is provided with a value of the bin duration of a time bin used for collecting data within said data collection session, said value is stored in said memory unit, wherein said set of timing parameters of said alert time window parameters comprises a starting bin number and an ending bin number and wherein said processor unit is adapted for computing the starting time point and ending time point of said alert time window from said bin duration, said starting bin number and said ending bin number, prior to starting of said alert time window within said current beat cycle.

55. The device according to claim 39 wherein said set of timing parameters comprises a set of approximation parameters and wherein said processing comprises using an approximation method to process said data collected from said heart in said data collection session to obtain a plurality of sets of approximation parameters usable for computing improved approximated values of the beginning time point and the ending time point of said alert time window.

56. The device according to claim 55 wherein said approximation method is a linear piecewise approximation method, said set of approximation parameters comprises a beginning time point parameter and a first slope parameter associated with said beginning time point parameter, an ending time point parameter and a second slope parameter associated with said ending time point parameter, and wherein said step of using comprises computing an approximated beginning time point for said alert time window of said current beat cycle from the values of the current cycle length measured for said current beat cycle, said first slope parameter and said beginning time point parameter, and computing an approximated ending time point for said alert time window of said current beat cycle from the values of said current cycle length, said second slope parameter and said ending time point parameter.

57. The device according to claim 56 wherein said current cycle length is the instantaneous cycle length determined from the current R—

R interval or the current A—

A interval measured for said current beat cycle.

58. The device according to claim 56 wherein said current cycle length is an average cycle length computed from the values of a plurality of consecutive R—

R intervals including the R—

R interval of said current beat cycle.

59. The device according to claim 50 wherein said current cycle length is an average cycle length computed from the values of a plurality of consecutive A—

A intervals including the A—

A interval of said current beat cycle.

60. The device according to claim 39 wherein said set of timing parameters comprises said beginning time point and said ending time point of said alert time window.

61. The device according to claim 39 wherein said set of data is a degenerate set of data in which at least some of said sets of alert time window parameters of said plurality of sets of alert time window parameters have identical values of said set of timing parameters.

62. The device according to claim 39 wherein said first cardiac site is the right ventricle of said heart and said second cardiac site is the left ventricle of said heart.

63. The device according to claim 39 wherein said first cardiac site is the right atrium of said heart and said second cardiac site is the left ventricle of said heart.

64. The device according to claim 39 wherein said excitable tissue control device is adapted to be implanted in said patient.

65. The device according to claim 39 wherein said excitable tissue control device is disposed out of said patient and is operatively connected to said plurality of electrodes adapted to be implanted in or about said heart of said patient.

66. An excitable tissue control device for setting on a beat by beat basis the parameters of an alert time window under a plurality of different cardiac conditions of a heart of a patient, the device comprising:

a plurality of electrodes adapted to be implanted in or about said heart;

means for detecting electrical depolarization events in a first cardiac site through at least a first electrode of said plurality of electrodes, said at least first electrode is disposed in or about said first cardiac site, and for detecting electrical depolarization events in a second cardiac site through at least a second electrode of said plurality of electrodes, said at least second electrode is disposed in or about said second cardiac site;

excitable tissue control means for delivering non-excitatory excitable tissue control signals to at least part of said second cardiac site through one or more electrodes of said plurality of electrodes;

memory means for storing a set of data, said set of data comprises a plurality of sets of alert time window parameters, each set of alert time window parameters is uniquely associated with a different set of values of a plurality of cardiac condition defining parameters identifying one of said plurality of different cardiac conditions, each set of alert time window parameters comprises at least a set of timing parameters usable for obtaining a beginning time point and an ending time point for said alert time window, each set of alert time window parameters is obtained by processing data collected from a plurality of cardiac beats of said heart of said patient under said plurality of different cardiac conditions within a data collection session performed in said patient;

processing means operatively connected to said detection means, said excitable tissue control means and said memory means, for receiving detection signals from said detection means, for controlling said excitable tissue control means by using the received detection signals, for updating in a current beat cycle of said heart the values of a plurality of cardiac condition defining variables corresponding to said cardiac condition defining parameters, for automatically selecting for said current beat cycle a current set of alert time window parameters of said plurality of sets of alert time window parameters based on the current values of said cardiac condition defining variables, for applying said current set of alert time window parameters to start said alert time window within said current beat cycle after detecting a first depolarization event at or about said first cardiac site and to terminate said alert time window, and for initiating the delivery of a delayed excitable tissue control signal at or about said second cardiac site upon detecting within the duration of said alert time window a depolarization event in or about said second cardiac site of said heart; and

a power source for providing power to said detection means, said processing means said memory means and said excitable tissue control means.

67. The device according to claim 66 further including telemetry means operatively connected to said power source and said processing means for telemetrically receiving data from a second telemetry means disposed outside said patient.

68. The device according to claim 66 further including pacing means operatively connected to said power source, said processing means and to at least one electrode of said plurality of electrodes, for delivering pacing pulses to said heart through said at least one electrode.