System and method for controlling the recording of diagnostic medical data in an implantable medical device

• US 7,447,544 B1
• Filed: 02/18/2004
• Issued: 11/04/2008
• Est. Priority Date: 02/18/2004
• Status: Expired due to Fees

• Current Assignee: Pacesetter Incorporated (Abbott Laboratories Incorporated)
• Original Assignee: Pacesetter Incorporated (Abbott Laboratories Incorporated)
• Inventors: Kroll, Mark W.
• Primary Examiner(s): Bockelman; Mark W
• Assistant Examiner(s): Bertram; Eric D
• Application Number:
  US10/782,123
• Time in Patent Office: 1,721 Days
• Field of Search: 600/509, 600/523, 600/508, 607/9
• US Class Current: 607/9
• CPC Class Codes: A61N 1/025 Digital circuitry features of electrotherapy devices, e.g. memory, clocks, processors
• CPC Class Codes: A61N 1/3621 for treating or preventing abnormally high heart rate

Abstract

Techniques are provided for controlling the recording of diagnostic data, such as intracardiac electrogram (IEGM) data, so as to reduce device power consumption. In one technique, the risk of onset of an arrhythmia is evaluated and the recording of diagnostic data is then selectively controlled based upon the evaluation. More specifically, a temporary “pre-trigger” memory for recording IEGM data is activated only at times when there is a significant risk that an arrhythmia will actually occur. Power savings are thereby achieved as compared to devices that require the pre-trigger memory to be continuously active. In another technique, parameters employed to trigger the recording of diagnostic data are adaptively modified to reduce the likelihood of any unnecessary recording of such data. Preferably, both the risk-based techniques and the adaptive techniques are implemented in the same system.

Claims

1. An implantable medical device comprising:

a device operative to monitor cardiac rhythm;

an implantable housing having therein a temporary memory operative to record diagnostic data corresponding to the cardiac rhythm; and

a long-term memory interfacing with the temporary memory and operative to record diagnostic data stored in the temporary memory; and

a processor operative to;

evaluate the cardiac rhythm for the detection of predetermined recording triggers indicative of an impending cardiac arrhythmia, wherein the cardiac arrhythmia indicated as impending, is not currently present;

control the recording of diagnostic data such that no data is recorded in the temporary memory until the detection of an impending cardiac arrhythmia, wherein the cardiac arrhythmia indicated as impending, is not currently present and no data is transferred from the temporary memory and recorded in the long-term memory until it has been determined that a cardiac arrhythmia did actually occur; and

adaptively modify the recording triggers so as to reduce the likelihood of any unnecessary recording of diagnostic data in the temporary memory.

2. The device of claim 1 wherein the diagnostic data to be recorded includes one or more of:

intracardiac electrograms (IEGMs) and event records.

3. The device of claim 1 wherein to control the recording of diagnostic data such that no data is recorded in the temporary memory until the detection of predetermined recording triggers, the processor is further operative to:

receive initial trigger parameters for triggering the recording of diagnostic data in the temporary memory;

monitor cardiac rhythm; and

selectively control the recording of diagnostic data in the temporary memory based on the cardiac rhythm and the trigger parameters.

4. The device of claim 3 wherein the trigger parameters include threshold values against which features of the cardiac rhythm are compared.

5. The device of claim 4 wherein the threshold values include one or more of:

heart rate variability threshold values, morphology threshold values, and fast beat threshold values.

6. The device of claim 4 wherein to adaptively modify the recording triggers the processor is further operative to selectively adjust the threshold values so as to reduce the likelihood of any unnecessary recording of diagnostic data in the temporary memory.

7. The device of claim 1 wherein to adaptively modify the recording triggers the processor is further operative to:

determine whether the recording triggers were properly indicative of an impending cardiac arrhythmia; and

if not, adjust the recording triggers to more effectively an impending cardiac arrhythmia.

8. The device of claim 7 wherein the recording triggers are indicative of the onset of an arrhythmia and wherein the recording triggers are adjusted based upon whether an arrhythmia in fact occurred.

9. The device of claim 8 wherein to evaluate the likelihood of an impending cardiac arrhythmia, the processor is further operative to detect the onset of an arrhythmia and wherein to control the recording of diagnostic data such that no data is recorded in the temporary memory until the detection of predetermined recording triggers, the processor is further operative to activate recording in the temporary memory upon detection of the onset of the arrhythmia.

10. The device of claim 9 wherein to monitor cardiac rhythm to detect the onset of an arrhythmia the processor is further operative to:

count a number of beats occurring at a rate above a predetermined rate threshold and detect the onset of an arrhythmia based on detection of a predetermined number of beats having a rate above the rate threshold.

11. The device of claim 10 wherein the predetermined number of beats having a rate above the rate threshold is in the range of one to three beats.

12. The device of claim 10 wherein the processor is further operative to confirm that an arrhythmia actually occurred and, if the arrhythmia is not confirmed, deactivate the recording of diagnostic data in the temporary memory.

13. The device of claim 9 wherein to adaptively modify the recording triggers so as to reduce the likelihood of any unnecessary recording of diagnostic data in the temporary memory the processor is further operative to selectively increment the number of beats required to trigger activation of the recording of diagnostic data in the temporary memory, if the arrhythmia is not confirmed.

14. The device of claim 13 wherein the processor is further operative to selectively increment the number of beats required to trigger activation of the recording of diagnostic data in the temporary memory upon detection of two consecutive episodes wherein the recording of diagnostic data was activated but the arrhythmia was not subsequently confirmed.

15. The device of claim 1 wherein to control the recording of diagnostic data such that no data is recorded in the temporary memory until the detection of predetermined recording triggers indicative of an impending cardiac arrhythmia, the processor is further operative to:

evaluate the likelihood of an impending cardiac arrhythmia; and

control the recording of diagnostic data based upon such an evaluation.

16. The device of claim 15 wherein to evaluate the likelihood of an impending cardiac arrhythmia, the processor is further operative to identify periods of time wherein there is an elevated risk of an arrhythmia and wherein to control the recording of diagnostic data such that no data is recorded in the temporary memory until the detection of predetermined recording triggers indicative of an impending cardiac arrhythmia, the processor is further operative to record the data in the temporary memory during the period of time wherein there is an elevated risk of an arrhythmia.

17. The device of claim 16 wherein to identify periods of time wherein there is an elevated risk of an arrhythmia the processor is further operative to monitor heart rate variability and to identify periods of time with reduced heart rate variability.

18. The device of claim 15 wherein to evaluate the likelihood of an impending cardiac arrhythmia, the processor is further operative to predict the onset of an arrhythmia and wherein to control the recording of diagnostic data such that no data is recorded in the temporary memory until the detection of predetermined recording triggers, the processor is further operative to activate recording in the temporary memory prior to the predicted onset of the arrhythmia.

19. The device of claim 18 wherein to predict the onset of an arrhythmia the processor is further operative to monitor cardiac rhythm.

20. The device of claim 19 wherein to monitor cardiac rhythm to predict the onset of an arrhythmia the processor is further operative to:

examine the morphology of heart beats and predict the onset of an arrhythmia based on detection of a significant change in morphology.

21. A method performed by an implantable medical device, the method comprising:

evaluating the likelihood of an impending cardiac arrhythmia, wherein an impending cardiac arrhythmia is an arrhythmia that is not currently present and wherein diagnostic medical data is to be recorded in an implanted long-term memory;

controlling the recording of diagnostic data based upon such an evaluation such that diagnostic medical data is first recorded in an implanted temporary memory only after it is determined that a cardiac arrhythmia that is not currently present is likely to arise, wherein the implanted temporary memory interfaces with the implanted long-term memory;

determining whether the impending cardiac arrhythmia actually occurred;

if such cardiac arrhythmia did actually occur, transferring the diagnostic data recorded in the implanted temporary memory to the implanted long-term memory; and

if such cardiac arrhythmia did not occur, adaptively modifying parameters employed to evaluate the likelihood of such cardiac arrhythmia so as to reduce the risk of unnecessarily recording of diagnostic data in the implanted temporary memory.

22. An implantable medical device comprising:

an implantable housing having therein a temporary memory operative to record diagnostic medical data; and

a long-term memory interfacing with the temporary memory and operative to record at least a portion of the diagnostic data stored in the temporary memory; and

an adaptive-based diagnostic controller operative to control the recording of diagnostic data such that no data is recorded in the temporary memory until the detection of predetermined recording triggers indicative of an impending cardiac arrhythmia, wherein the cardiac arrhythmia indicated as impending, is not currently present, and no data is transferred from the temporary memory and recorded in the long-term memory until it has been determined that a cardiac arrhythmia did actually occur and further operative to adaptively modifying the recording triggers so as to reduce the likelihood of any unnecessary recording of diagnostic data in the temporary memory.

23. A system for adaptively controlling the recording of diagnostic data within an implantable medical device comprising:

an implantable housing having therein, means for temporarily storing data; and

means for long-term storage of data stored in the means for temporarily storing data, wherein the means for temporarily storing data interfaces with the means for long-term storage of data;

means for controlling the recording of diagnostic data within the means for temporarily storing data such that no data is stored in the means for temporarily storing data until the detection of predetermined recording triggers indicative of an impending cardiac arrhythmia, wherein the cardiac arrhythmia indicated as impending, is not currently present and no data is transferred from the means for temporarily storing data and recorded in the means for long-term storage of data until it has been determined that a cardiac arrhythmia did actually occur; and

means for adaptively modifying the recording triggers so as to reduce the likelihood of any unnecessary recording of diagnostic data in the means for temporarily storing data.