VALIDITY TEST ADAPTIVE CONSTRAINT MODIFICATION FOR CARDIAC DATA USED FOR DETECTION OF STATE CHANGES

• US 20110270347A1
• Filed: 04/30/2010
• Published: 11/03/2011
• Est. Priority Date: 04/29/2010
• Status: Active Grant

• Current Assignee: Cyberonics, Inc
• Original Assignee: Cyberonics, Inc
• Inventors: Osorio, Ivan, Frei, Mark
• Granted Patent: US 8,649,871 B2
• Time in Patent Office: Days
• US Class Current: 607/45
• CPC Class Codes: A61B 5/02405 Determining heart rate variability
• CPC Class Codes: A61B 5/0245 by using sensing means generating electric signals, i.e. ECG signals
• CPC Class Codes: A61B 5/352 Detecting R peaks, e.g. for synchronising diagnostic apparatus; Estimating R-R interval
• CPC Class Codes: A61B 5/4094 Diagnosing or monitoring seizure diseases, e.g. epilepsy
• CPC Class Codes: A61N 1/36053 adapted for vagal stimulation A61N1/36114 takes precedence
• CPC Class Codes: A61N 1/36064 Epilepsy
• CPC Class Codes: A61N 1/36139 with automatic adjustment

Abstract

Methods, systems, and apparatus for quantifying the quality of a fiducial time marker for a candidate heart beat, quantifying the quality of a candidate heart beat, or determining a time of beat sequence of the patient'"'"'s heart. A fiducial time marker is obtained for a candidate heart beat. A quality index of said candidate heart beat is set to a first value. The candidate heart beat is tested with at least one beat validity test. At least a second value is added to said quality index of said candidate heart beat if said candidate heart beat passes said at least one beat validity test. The candidate heart beat is tested with at least a second heart beat validity test. At least a third value is added to said quality index of said candidate heart beat if said candidate heart beat passes said at least second heart beat validity test. In one class of beat validity test, a constraint defining a pass is modified at one or more times after the most recent prior valid heart beat that is greater than a constraint modification time threshold

Claims

1. A computer readable program storage unit encoded with instructions that, when executed by a computer, perform a method for determining a time of beat sequence of the patient'"'"'s heart, comprising:

obtaining a time series of fiducial time markers for candidate heart beats;

identifying 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;

accepting 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; and

performing at least one responsive action based upon at least one said valid heart beat, the responsive action selected from the group consisting of

issuing a detection for an epileptic seizure event;

delivering a neurostimulation therapy to the patient to treat an epileptic seizure event;

warning at least one of a caregiver, the patient, or a physician; and

logging said modified constraint to a memory.

2. The computer readable program storage unit of claim 1, wherein delivering a neurostimulation therapy comprises one of

initiating a programmed neurostimulation therapy;

and

modifying a programmed neurostimulation therapy to obtain a second neurostimulation therapy and applying said second neurostimulation therapy to a target neural structure.

3. The computer readable program storage unit of claim 1, wherein the constraint is modified by relaxing said constraint by from about 1% to about 50%.

4. The computer readable program storage unit of claim 1, wherein the constraint is modified by relaxing said constraint by greater than about 50%.

5. The computer readable program storage unit of claim 1, wherein the constraint is modified by tightening said constraint by greater than about 1%.

6. The computer readable program storage unit of claim 1, wherein the constraint is modified once after the constraint modification time threshold is passed.

7. The computer readable program storage unit of claim 1, wherein the constraint is modified at a plurality of times after the constraint modification time threshold is passed.

8. The computer readable program storage unit of claim 1, wherein the constraint is modified according to a step function at one or more times after the constraint modification time threshold is passed.

9. The computer readable program storage unit of claim 1, wherein the constraint is modified according to a linear function over a range of times after the constraint modification time threshold is passed.

10. The computer readable program storage unit of claim 1, wherein the constraint is modified according to a non-linear function over a range of times after the constraint modification time threshold is passed.

11. The computer readable program storage unit of claim 1, wherein the constraint is modified to no more than a finite maximum value or no less than a finite minimum value.

12. The computer readable program storage unit of claim 1, wherein the constraint is modified up to infinity or down to negative infinity.

13. 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; and

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; and

at least one responsive action module adapted to perform at least one action based upon at least one said valid heart beat, the responsive action module selected from the group consisting of

a seizure detection module;

a neurostimulation delivery module;

a warning module; and

a modified constraint logging module.

14. The medical device of claim 13, wherein the responsive action module is a seizure detection module.

15. A method for determining a time of beat sequence of the patient'"'"'s heart, comprising:

obtaining a time series of fiducial time markers for candidate heart beats;

identifying 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;

accepting 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; and

performing at least one responsive action based upon at least one said valid heart beat, the responsive action selected from the group consisting of

issuing a detection for an epileptic seizure event;

delivering a neurostimulation therapy to the patient to treat an epileptic seizure event;

warning at least one of a caregiver, the patient, or a physician; and

logging said modified constraint to a memory.

16. The method of claim 15, wherein delivering a neurostimulation therapy comprises one of

initiating a programmed neurostimulation therapy;

and

modifying a programmed neurostimulation therapy to obtain a second neurostimulation therapy and applying said second neurostimulation therapy to a target neural structure.

17. The method of claim 15, wherein the constraint is modified once after the constraint modification time threshold is passed.

18. The method of claim 15, wherein the constraint is modified according to a linear function over a range of times after the constraint modification time threshold is passed.

19. The method of claim 15, wherein the constraint is modified to no more than a finite maximum value or no less than a finite minimum value.

20. The method of claim 15, wherein the constraint is modified up to infinity or down to negative infinity.