Validity test adaptive constraint modification for cardiac data used for detection of state changes

1. A medical device, comprising:

a sensor adapted to detect a candidate heart beat;

a cardiac data collection module operatively coupled to said sensor, said cardiac data collection module adapted to obtain a time series of fiducial time markers for candidate heart beats;

a constraint-modifying heart beat validation module operatively coupled to said sensor and said cardiac data collection module, said constraint-modifying heart beat validation module adapted to identify valid heart beats from said candidate heart beats by subjecting a plurality of said candidate heart beats to at least one beat validity test, said at least one beat validity test comprising at least one interbeat interval test applied to a candidate heart beat interval derived from a candidate heart beat and at least one prior heart beat, and accept as valid heart beats the candidate heart beats that pass said at least one beat validity test, wherein a constraint defining said pass is modified after the most recent prior valid heart beat that is greater than a constraint modification time threshold;

a seizure detection module configured to detect an epileptic seizure using a seizure detection algorithm based on said accepted valid heart beats; and

at least one responsive action module adapted to perform at least one action based upon an epileptic seizure detected by said seizure detection module, the responsive action module selected from the group consisting of:

a neurostimulation delivery module;

a warning module; and

a modified constraint logging module.

2. The medical device of claim 1 , wherein the neurostimulation delivery module is configured to initiate a programmed neurostimulation therapy.

3. The medical device of claim 1 , wherein the neurostimulation delivery module is configured to modify a programmed neurostimulation therapy to obtain a second neurostimulation therapy and applying said second neurostimulation therapy to a target neural structure.

4. The medical device of claim 1 , further comprising a neurostimulation electrode configured to be coupled to a target neural structure; and wherein the neurostimulation delivery module is configured to apply a neurostimulation therapy via the neurostimulation electrode to the target neural structure.

5. The medical device of claim 4 , wherein the target neural structure is a cranial nerve.

6. The medical device of claim 5 , wherein the cranial nerve is a vagus nerve.

7. The medical device of claim 1 , wherein the constraint-modifying heart beat validation module is configured to relax said constraint from 1% to 50%.

8. The medical device of claim 1 , wherein the constraint-modifying heart beat validation module is configured to modify said constraint once after the constraint modification time threshold is passed.

9. The medical device of claim 1 , wherein the cardiac data collection module is configured to obtain as fiducial time markers one or more of a time-stamped R-wave peak; a time-stamped R-wave threshold crossing; a time-stamped P-wave peak; a time-stamped P-wave threshold crossing; a time-stamped T-wave peak; or a time-stamped T-wave threshold crossing.

10. A medical device, comprising:

a data collection module adapted to receive a time series of fiducial time markers for candidate heart beats; and

a constraint-modifying heart beat validation module operatively coupled to said data collection module, said constraint-modifying heart beat validation module adapted to identify valid heart beats from said candidate heart beats by subjecting a plurality of said candidate heart beats to at least one beat validity test, said at least one beat validity test comprising at least one interbeat interval test applied to a candidate heart beat interval derived from a candidate heart beat and at least one prior heart beat, and accept as valid heart beats the candidate heart beats that pass said at least one beat validity test, wherein a constraint defining said pass is modified after the most recent prior valid heart beat that is greater than a constraint modification time threshold;

a seizure detection module configured to detect an epileptic seizure using a seizure detection algorithm based on said accepted valid heart beats: and

at least one responsive action module adapted to perform at least one action based upon an epileptic seizure detected by said seizure detection module, the responsive action module selected from the group consisting of:

a neurostimulation delivery module;

a warning module; and

a modified constraint logging module.

11. The medical device of claim 10 , further comprising a sensor module adapted to provide data for determining said time series of fiducial time markers for candidate heart beats.

12. The medical device of claim 11 , wherein said sensor module comprises a plurality of sensors each capable of providing a signal indicative of a heart beat.

13. The medical device of claim 10 , wherein the neurostimulation delivery module is configured to initiate a programmed neurostimulation therapy.

14. The medical device of claim 10 , wherein the neurostimulation delivery module is configured to modify a programmed neurostimulation therapy to obtain a second neurostimulation therapy and applying said second neurostimulation therapy to a target neural structure.

15. The medical device of claim 10 , further comprising a neurostimulation electrode configured to be coupled to a target neural structure; and wherein the neurostimulation delivery module is configured to apply a neurostimulation therapy via the neurostimulation electrode to the target neural structure.

16. A system, comprising:

a sensor adapted to detect a candidate heart beat of a patient;

a medical device operatively coupled to said sensor, said medical device comprising:

a cardiac data collection module operatively coupled to said sensor, said cardiac data collection module adapted to obtain a time series of fiducial time markers for candidate heart beats;

a constraint-modifying heart beat validation module operatively coupled to said sensor and said cardiac data collection module, said constraint-modifying heart beat validation module adapted to identify valid heart beats from said candidate heart beats by subjecting a plurality of said candidate heart beats to at least one beat validity test, said at least one beat validity test comprising at least one interbeat interval test applied to a candidate heart beat interval derived from a candidate heart beat and at least one prior heart beat, and accept as valid heart beats the candidate heart beats that pass said at least one beat validity test, wherein a constraint defining said pass is modified after the most recent prior valid heart beat that is greater than a constraint modification time threshold;

a seizure detection module configured to detect an epileptic seizure using a seizure detection algorithm based on said accepted valid heart beats; and

at least one responsive action module adapted to perform at least one action based upon an epileptic seizure detected by said seizure detection module, the responsive action module selected from the group consisting of:

a neurostimulation delivery module;

a warning module; and

a modified constraint logging module;

and

an electrode operatively coupled to said medical device and to a portion of said patient's body, wherein said electrode is capable of delivering a neurostimulation therapy to said portion of said patient's body.

17. The system of claim 16 , wherein the neurostimulation delivery module is configured to initiate a programmed neurostimulation therapy.

18. The system of claim 16 , wherein the neurostimulation delivery module is configured to modify a programmed neurostimulation therapy to obtain a second neurostimulation therapy and applying said second neurostimulation therapy to a target neural structure.

19. The system of claim 16 , further comprising a neurostimulation electrode configured to be coupled to a target neural structure; and wherein the neurostimulation delivery module is configured to apply a neurostimulation therapy via the neurostimulation electrode to the target neural structure.