Detection of heart failure decompensation based on cumulative changes in sensor signals

1. A method, comprising:

acquiring sensor data associated with one or more symptoms of heart failure;

calculating a cumulative sum from the sensor data;

evaluating the cumulative sum to determine a change in the one or more heart failure symptoms by comparing the cumulative sum to one or both of a threshold and a V-mask, wherein the cumulative sum exceeding the threshold or the V-mask indicates change in the one or more heart failure symptoms; and

generating an output in response to the cumulative sum exceeding one or both of the threshold and the V-mask, wherein generating the output comprises at least one of triggering an alert and changing delivery of a therapy, wherein at least one of evaluating, comparing, and generating is implemented at least in part by circuitry.

2. The method of claim 1 , wherein acquiring the sensor data comprises:

generating a transthoracic impedance signal; and

extracting statistical features from the transthoracic impedance signal.

3. The method of claim 1 , wherein acquiring the sensor data comprises:

acquiring heart sounds data; and

extracting statistical features from the heart sounds data.

4. The method of claim 1 , wherein acquiring the sensor data comprises:

acquiring patient activity data; and

extracting statistical features from the patient activity data.

5. The method of claim 1 , wherein acquiring the sensor data comprises:

acquiring heart rate variability data; and

extracting statistical features from the heart rate variability data.

6. The method of claim 1 , wherein acquiring the sensor data comprises:

acquiring apnea/hypopnea index data; and

extracting statistical features from the apnea/hypopnea index data.

7. The method of claim 1 , wherein the acquired sensor data comprises data associated with one or more cardiac parameters.

8. The method of claim 1 , wherein acquiring the sensor data comprises acquiring data from a single sensor.

9. The method of claim 1 , wherein:

acquiring the sensor data comprises acquiring the sensor data from multiple sensors; and

developing the cumulative sum comprises developing a multivariate cumulative sum.

10. The method of claim 1 , acquiring the sensor data comprises acquiring the sensor data based on signals sensed within a moving time window.

11. The method of claim 1 , wherein calculating the cumulative sum comprises:

trending the sensor data in a moving window;

determining a slope of the sensor data trended in the moving window; and

calculating the cumulative sum of the slope.

12. The method of claim 1 , wherein:

evaluating the cumulative sum comprises detecting a shift in the cumulative sum; and

generating the output comprises generating a status alert based on the shift.

13. The method of claim 1 , wherein generating the output comprises controlling the therapy based on the evaluation of the cumulative sum.

14. The method of claim 1 , wherein at least one of acquiring the sensor data, calculating the cumulative sum, evaluating the cumulative sum, and generating the output are performed at least in part by implantable circuitry.

15. A medical device, comprising:

sensing circuitry configured to acquire sensor data associated with one or more symptoms of heart failure; and

a diagnostics processor configured to calculate a cumulative sum of the sensor data, evaluate the cumulative sum to determine whether the cumulative sum exceeds one or both of a threshold and a V-mask indicating change in one or more heart failure symptoms, and generate an output in response to the cumulative sum exceeding one or both of the threshold and the V-mask.

16. The medical device of claim 15 , wherein the sensing circuitry comprises a sensor configured to sense transthoracic impedance, the sensing circuitry configured to acquire the sensor data based on the transthoracic impedance signal.

17. The medical device of claim 15 , wherein at least one of the sensing circuitry and the diagnostics processor comprises an implantable component.

18. The medical device of claim 15 , wherein the diagnostics processor is configured to extract statistical features from the sensor data and to calculate the cumulative sum of the extracted statistical features.

19. The medical device of claim 15 , wherein the diagnostics processor is configured to trend the sensor data, determine a slope of the trend, and calculate the cumulative sum of the slope.

20. The medical device of claim 15 , wherein the medical device further comprises an alarm unit coupled to the diagnostics processor, the diagnostics processor is configured to evaluate the cumulative sum by detecting a shift in the cumulative sum, and the alarm unit is configured issue an alert when the shift exceeds one or both of the threshold and the V-mask.

21. The medical device of claim 15 , wherein the medical device further comprises a therapy control unit coupled to the diagnostics processor, the therapy control unit used to control a therapy based on the evaluation of the cumulative sum indicating one or more heart failure symptoms.

22. The medical device of claim 21 , wherein the therapy comprises a cardiac pacing therapy.

23. A medical system, comprising:

means for acquiring sensor data associated with one or more symptoms of heart failure;

means for calculating a cumulative sum of the sensor data;

means for evaluating the cumulative sum to determine a change in the cumulative sum relative to one or both of a threshold and a V-mask, wherein the cumulative sum exceeding the threshold or V-mask indicates a change in one or more heart failure symptoms; and

means for generating an output in response to the cumulative sum exceeding one or both of the threshold and the V-mask.

24. The system of claim 23 , further comprising:

means for generating a respiration signal; and

means for extracting statistical features from the respiration signal.

25. The system of claim 23 , further comprising:

means for detecting a shift in the cumulative sum; and

means for generating a status alert based on the generated output.

26. The system of claim 23 , further comprising means for controlling a therapy based on the generated output.

27. The system of claim 26 , wherein the therapy is biventricular pacing.