Implantable cardiac device having precision RRT indication

• US 6,400,988 B1
• Filed: 02/18/2000
• Issued: 06/04/2002
• Est. Priority Date: 02/18/2000
• Status: Expired due to Term

• Current Assignee: Pacesetter Incorporated (Abbott Laboratories Incorporated)
• Original Assignee: Pacesetter Incorporated (Abbott Laboratories Incorporated)
• Inventors: Gurewitsch, Reinaldo
• Primary Examiner(s): LAYNO, CARL HERNANDZ
• Application Number:
  US09/507,023
• Time in Patent Office: 837 Days
• Field of Search: 607/5, 607/9, 607/29
• US Class Current: 607/29
• CPC Class Codes: A61N 1/3708 for power depletion

Abstract

An implantable cardiac device including a depletable power source, having an initial energy capacity, and method provide precise recommended replacement time and end of life indications for the depletable power source. The recommended replacement times and end of life times are based upon the actual remaining energy of the depletable power source. The recommended replacement time and end of life time are stored in memory for later transmission by a telemetry circuit to a nonimplantable receiver for read out or display.

Claims

1. An implantable cardiac device having a precise indicator of replacement time, comprising:

a power source having an initial energy capacity;

pulse generating means for generating stimulation pulses which deplete the energy capacity of the power source;

prediction means for predicting a remaining energy capacity of the power source based on an actual energy used by the pulse generating means; and

means for generating an indicator, based upon the actual remaining energy capacity of the power source, corresponding to the replacement time of the power source.

2. The device of claim 1, wherein the prediction means comprises:

means for subtracting the actual used energy from the initial energy capacity to determine the actual remaining energy.

3. The device of claim 2, wherein the device further comprises:

means for determining an energy depletion time of the power source;

means for determining average energy depletion rate over the energy depletion time; and

means for determining the actual energy used based upon the average energy depletion and the energy depletion time.

4. The device of claim 1, further comprising:

means for determining average energy depletion rate; and

means for determining remaining power source life based upon the remaining energy capacity and the average energy depletion rate.

5. The device of claim 4, wherein:

the remaining power source life is in day units; and

the indicator generating means comprises means for determining a date of power source depletion based upon the remaining power source life and a current date, the date of power source depletion being a first indicator.

6. The device of claim 5, wherein the indicator generating means further comprises:

means for dynamically determining a recommended replacement date for replacing the depletable power source based upon the date of power source depletion date and a fixed time period prior to the date of power source depletion, the recommended replacement date being a second indicator.

7. The device of claim 5, further comprising alarm means for issuing a discernable alarm when the current date equals or exceeds the date of power source depletion.

8. The device of claim 6, further comprising alarm means for issuing a discernable alarm when the current date equals or exceeds the recommended replacement date.

9. The device of claim 4, wherein the average energy depletion rate is an average energy depletion rate of at least a previous twenty-four hour period.

10. An implantable cardiac device having an improved means for predicting replacement time, the device comprising:

a power source having an initial energy capacity;

pulse generating means for generating stimulation pulses which deplete the energy capacity of the power source; and

a processor programmed to predict the recommended replacement time based on actual energy used, and to generate an indicator when the recommended replacement time has been exceeded.

11. The device of claim 10, wherein the processor is programmed to predict the recommended replacement time by determining actual energy used and to subtract the actual used energy from the initial energy capacity to determine the actual remaining energy capacity.

12. The device of claim 11, wherein the processor is further programmed to determine an energy depletion time of the power source, to determine average energy depletion rate over the energy depletion time, and to determine the actual used energy based upon the average energy depletion and the energy depletion time.

13. The device of claim 10, wherein the processor is further programmed to determine average energy depletion rate and remaining power source life based upon the remaining energy and the average energy depletion rate.

14. The device of claim 10, wherein the processor is further programmed to predict the absolute replacement time, and to generate an indicator when the absolute replacement time has been exceeded.

15. The device of claim 14, wherein the remaining power source life is in day units and wherein the processor is further programmed to determine an absolute replacement date based upon the remaining power source life and a current date, the absolute replacement date being a first indicator.

16. The device of claim 15, wherein the processor is further programmed to determine a recommended replacement date for replacing the depletable power source based upon the date of absolute replacement date and a fixed time period prior to the absolute replacement date, the recommended replacement date being a second indicator.

17. The device of claim 15, further comprising an alarm that issues a discernable alarm when the current date equal or exceeds the absolute replacement date.

18. The device of claim 16, further comprising an alarm that issues a discernable alarm when the current date equal or exceeds the recommended replacement date.

19. The device of claim 13, wherein the average energy depletion rate is an average energy depletion rate of at least a last twenty-four hour period.

20. In an implantable cardiac device having a power source having an initial energy capacity, a method of monitoring energy depletion of the power source, the method comprising the steps of:

dynamically determining one of a recommended replacement time or an absolute replacement time based on an actual remaining energy of the power source; and

generating an indicator, based upon the actual remaining energy of the power source, corresponding to one of a recommended replacement time or an absolute replacement time.

21. The method of claim 20, further comprising the step of determining the actual remaining energy based on determining actual used energy and subtracting the actual used energy from the initial energy capacity.

22. The method of claim 21, wherein the step of determining actual used energy comprises the steps of determining an energy depletion time of the power source, determining average energy depletion rate over the energy depletion time, and multiplying the average energy depletion rate by the energy depletion time.

23. The method of claim 20, further comprising the steps of determining average energy depletion rate, and dividing the remaining energy by the average energy depletion rate to determine remaining power source life.

24. The method of claim 23, wherein the remaining power source life is in day units and wherein the method further comprises the step of adding the remaining power source life to a current date to determine a date of power source depletion as a first indicator.

25. The method of claim 24, comprising the further step of subtracting a fixed time from the date of power source depletion to determine a recommended replacement date as a second indicator.

26. The method of claim 24, comprising the further step of issuing a discernable alarm when the date of power source depletion is a current date.

27. The method of claim 25, comprising the further step of issuing a discernable alarm when the recommended replacement date is a current date.

28. The device of claim 25, wherein the average energy depletion rate is an average energy depletion rate of a last twenty-four hour period.

29. A method for determining a time remaining to a recommended replacement time of a battery of an implantable cardiac stimulating device, comprising:

determining a first amount of battery capacity actually depleted as a function of an actual battery current used over a depletion time interval;

defining a second amount of battery capacity corresponding to recommended replacement time;

determining an amount of battery capacity remaining until the recommended battery replacement time by subtracting the first amount of battery capacity from the second amount of battery capacity;

measuring an amount of battery current needed to maintain a present level of therapy; and

predicting the time remaining to the recommended battery replacement time based on the amount of battery capacity remaining and the amount of battery current needed to maintain the present level of therapy.

30. The method of claim 29, further comprising:

defining the actual battery current used over a depletion time interval as an average current depletion rate over a time interval between battery attachment and interrogation.

31. The method of claim 29, wherein the measuring step comprises:

determining a most-recent average current depletion representative of a patient'"'"'s present level of therapy.

32. The method of claim 31, wherein the most-recent average current depletion is an average current depleted over at least a previous twenty-four hour period.

33. The method of claim 31, wherein:

the most-recent average current depletion is an average current used over approximately a previous twenty-four hour period; and

the time remaining is calculated in day-units.

34. An implantable cardiac device that determines a time remaining to a replacement time of a battery, comprising:

a battery current measuring circuit that measures an actual battery current used over a depletion time interval to produce a value for an actual battery capacity depleted, and further measures an amount of battery current needed to maintain a present level of therapy; and

a memory for storing a total amount of battery capacity corresponding to a battery replacement time, the battery replacement time being one of a recommended replacement time or an end-of-life time;

a control circuit that determines a remaining amount of battery capacity by subtracting the actual battery capacity depleted from the total amount of battery capacity, the control circuit further predicting the battery replacement time based on the amount of battery capacity remaining and the amount of battery current needed to maintain the present level of therapy.

35. The device of claim 34, wherein:

the battery current measuring circuit measures the actual battery current used over a depletion time interval by measuring an average current depletion over a time interval between battery attachment and interrogation.

36. The device of claim 34, wherein:

the battery current measuring circuit measures the amount of battery current needed to maintain a present level of therapy by measuring a most-recent average current depletion representative of a patient'"'"'s most-recent level of therapy.

37. The device of claim 36, wherein:

the battery current measuring circuit measures the most-recent average current depletion by measuring an average current depleted over at least a previous twenty-four hour period.

38. The device of claim 36, wherein:

the battery current measuring circuit measures the most-recent average current depletion by measuring an average current depleted approximately a previous twenty-four hour period; and

the control circuit predicts the battery replacement time in day-units.

39. An implantable cardiac device that determines a time remaining to a desired replacement time of a battery, comprising:

measuring means for measuring a value for an actual battery capacity depleted based on an actual battery current and a depletion time interval, and further for measuring an amount of battery current needed to maintain a present level of therapy; and

storing means for storing a total amount of battery capacity corresponding to the desired replacement time;

determining means for determining a remaining amount of battery capacity, and for determining the desired replacement time based on the amount of battery capacity remaining and the amount of battery current needed to maintain the present level of therapy.

40. The device of claim 39, wherein:

the measuring means further comprises means for measuring the actual battery current used over a depletion time interval by measuring an average current depletion over a time interval between battery attachment and interrogation.

41. The device of claim 39, wherein:

the measuring means further comprises means for measuring the amount of battery current needed to maintain a present level of therapy by measuring a most-recent average current depletion representative of a patient'"'"'s most-recent level of therapy.

42. The device of claim 41, wherein:

the determining means further comprises means for determining the battery replacement time in day-units.

43. In an implantable cardiac device having a battery which has an initial energy capacity, a method of determining a replacement time, the method comprising:

dynamically determining the replacement time based on actual total energy capacity used and predicted future use based on recent energy capacity usage; and

reporting one of a replacement time or a replacement date whenever interrogation occurs after a battery is connected and until battery end-of-life.

44. The method of claim 43, further comprising:

measuring a long-term average and a short-term average of the actual battery current used; and

wherein the long-term average battery current is used to calculate the actual total energy capacity used and the short-term average battery current is used to predict future use.

45. An implantable cardiac device having a battery which has an initial energy capacity for determining a replacement time, comprising:

control circuitry that is programmed to dynamically determine the replacement time based on actual total energy capacity used and predicted future use based on recent energy capacity usage; and

telemetry circuitry that is capable of transmitting one of a replacement time or a replacement date whenever interrogation occurs after a battery is connected and until battery end-of-life.

46. The method of claim 45, further comprising:

measurement circuitry that measures a long-term average and a short-term average of the actual battery current used; and

wherein the long-term average battery current is used to calculate the actual total energy capacity used and the short-term average battery current is used to predict future use.

47. An implantable cardiac device having a battery which has an initial energy capacity, comprising:

means for determining actual total energy capacity used;

means for determining a predicted future use based on recent energy capacity usage;

means for dynamically determining the replacement time based on actual total energy capacity used and predicted future use based on recent energy capacity usage; and

means for reporting one of a desired replacement time or a desired replacement date whenever interrogation occurs after a battery is connected and until battery end-of-life.

48. The method of claim 47, further comprising:

measurement circuitry that measures a long-term average and a short-term average of the actual battery current used; and

wherein the long-term average battery current is used to calculate the actual total energy capacity used and the short-term average battery current is used to predict future use.

49. A method for determining a time remaining to a desired replacement time of a battery of an implantable cardiac stimulating device, comprising:

determining a first amount of battery capacity actually depleted as a function of an actual battery current used over a depletion time interval;

defining a second amount of battery capacity corresponding to a desired replacement time; and

determining an amount of actual battery capacity remaining until the desired battery replacement time by subtracting the first amount of battery capacity from the second amount of battery capacity,

determining the desired battery replacement time based on the actual amount of battery capacity remaining.

50. A system for determining a time remaining to a desired replacement time of a battery of an implantable cardiac stimulating device, comprising:

a current monitoring circuit that monitors a first amount of battery capacity actually depleted as a function of an actual battery current used over a depletion time interval, and further monitors a remaining battery capacity based on the difference between the first amount of battery capacity and a second amount of battery capacity that corresponds to desired replacement time; and

a control circuit that is operative to determine a time for the desired replacement of the device based on the remaining battery capacity.

51. A system for determining a time remaining to a desired replacement time of a battery of an implantable cardiac stimulating device, the battery having a predetermined amount of battery capacity corresponding to a desired replacement time, the system comprising:

means for determining an amount of actual battery capacity remaining based on the difference between the predetermined amount of battery capacity and a first amount of battery capacity actually depleted corresponding to an actual battery current used over a depletion time interval;

determining the desired battery replacement time based on the actual amount of