Dynamic heart rate threshold for neurological event detection

• US 9,402,550 B2
• Filed: 04/29/2011
• Issued: 08/02/2016
• Est. Priority Date: 04/29/2011
• Status: Active Grant

• Current Assignee: LivaNova USA, Inc. (LivaNova Plc)
• Original Assignee: Cybertronics Incorporated
• Inventors: Colborn, John C
• Primary Examiner(s): Kahelin, Michael
• Assistant Examiner(s): PHAM, MINH DUC GIA
• Application Number:
  US13/097,439
• Publication Number:
  US 20120277605A1
• Time in Patent Office: 1,922 Days
• Field of Search: 600/544, 600/508, 607/45
• US Class Current: 1/1
• CPC Class Codes: A61B 5/02 Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
• CPC Class Codes: A61B 5/024 Detecting, measuring or recording pulse rate or heart rate A61B5/0205, A61B5/021 take precedence
• CPC Class Codes: A61B 5/37 Intracranial electroencephalography [IC-EEG], e.g. electrocorticography [ECoG]
• CPC Class Codes: A61B 5/7275 Determining trends in physiological measurement data; Predicting development of a medical condition based on physiological measurements, e.g. determining a risk factor

Abstract

A method may include sensing a time of beat sequence of a patient'"'"'s heart and processing said time of beat sequence with a medical device to identify a change in heart rate of a patient from a first heart rate to a second heart rate. The method may continue by determining with the medical device at least one of a) a ratio of the second heart rate to the first heart rate and b) a difference between the second heart rate and the first heart rate. The method may include determining with the medical device at least one of a) a dynamic ratio threshold for the ratio and b) a dynamic difference threshold for the difference, wherein the at least one threshold is based upon the first heart rate. The ratio and/or the difference may be compared to the threshold(s) to detect a neurological event, for example, an epileptic seizure.

Claims

1. A method, comprising:

sensing a time of beat sequence of a patient'"'"'s heart;

processing the time of beat sequence with a medical device to identify a change in heart rate of a patient from a first heart rate to a second heart rate;

determining with the medical device a ratio of the second heart rate to the first heart rate;

continuously updating the first heart rate;

autonomously determining with the medical device a first dynamic ratio threshold for the ratio based on a first patient activity and a second dynamic ratio threshold for the ratio based on a second patient activity;

autonomously determining with the medical device a current dynamic ratio threshold for the ratio which is within a range between the first dynamic ratio threshold and the second dynamic ratio threshold, wherein the current dynamic ratio threshold is based upon a most recently updated window of the first heart rate;

comparing the ratio to the current dynamic ratio threshold; and

detecting a neurologic event based on an occurrence of the ratio exceeding the current dynamic ratio threshold.

2. The method of claim 1, wherein the current dynamic ratio threshold decreases as the first heart rate increases.

3. The method of claim 1, wherein the neurologic event is an epileptic seizure.

4. The method of claim 1, further comprising:

initiating at least one responsive action selected from;

logging at least one of a neurological event occurrence, a time of occurrence of the neurological event, or a severity measure of the neurological event;

issuing a warning of the neurological event;

issuing an alarm;

initiating a responsive therapy to treat the neurologic event; and

sending an email to at least one of the patient, a caregiver, a responder, and a physician.

5. The method of claim 4, wherein the responsive therapy comprises applying an electrical signal to at least one cranial nerve selected from a vagus nerve, a trigeminal nerve, a glossopharyngeal nerve, a hypoglossal nerve, and branches of the foregoing.

6. The method of claim 1, wherein:

the second heart rate comprises a first statistical measure of central tendency in a short-term window ending in a present time; and

the first heart rate comprises a second statistical measure of central tendency in a time window beginning prior to a start of the short-term window from which the second heart rate is determined.

7. The method of claim 1, wherein determining the current dynamic ratio threshold is further based on the first heart rate and a maximum heart rate of the patient.

8. The method of claim 1, wherein determining the current dynamic ratio threshold is further based on the first heart rate and a resting heart rate of the patient.

9. An article of manufacture comprising a computer-readable non-transitory storage medium having programming configured to cause processing circuitry to perform processing including:

sensing a time of beat sequence of a patient'"'"'s heart;

processing the time of beat sequence with a medical device to identify a change in heart rate of a patient from a first heart rate to a second heart rate;

continuously updating the first heart rate;

determining with the medical device a ratio of the second heart rate to the first heart rate;

autonomously determining with the medical device a first dynamic ratio threshold for the ratio based on a first patient activity and a second dynamic ratio threshold for the ratio based on a second patient activity;

autonomously determining with the medical device a current dynamic ratio threshold for the ratio which is within a range between the first dynamic ratio threshold and the second dynamic ratio threshold, wherein the current dynamic ratio threshold is based upon a most recently updated window of the first heart rate;

comparing the ratio to the current dynamic ratio threshold; and

detecting a neurologic event based on an occurrence of the ratio exceeding the current dynamic ratio threshold.

10. The article of claim 9, wherein the current dynamic ratio threshold decreases as the first heart rate increases.

11. The article of claim 9, wherein the neurologic event is an epileptic seizure.

12. The article of claim 9, wherein the first heart rate is a background heart rate and the second heart rate is a foreground heart rate.

13. An apparatus, comprising:

at least one sensor configured to sense a time of beat sequence of a patient'"'"'s heart;

a medical device comprising;

a) a heart rate determination module configured to identify from the time of beat sequence a change in heart rate of a patient from a first heart rate to a second heart rate, and continuously update the first heart rate;

b) a parameter determination module configured to determine a ratio of the second heart rate to the first heart rate;

c) a dynamic threshold determination module configured to autonomously determine a first dynamic ratio threshold for the ratio based on a first patient activity and a second dynamic ratio threshold for the ratio based on a second patient activity, the dynamic threshold determination module configured to autonomously determining with the medical device a current dynamic ratio threshold for the ratio which is within a range between the first dynamic ratio threshold and the second dynamic ratio threshold, wherein the current dynamic ratio threshold is based upon a most recently updated window of the first heart rate; and

d) a comparison module configured to compare the ratio to the current dynamic ratio threshold; and

e) a neurologic event detection module configured to detect a neurologic event based on an occurrence of the ratio exceeding the current dynamic ratio threshold.

14. The apparatus of claim 13, wherein the current dynamic ratio threshold determined by the dynamic threshold determination module decreases as the first heart rate increases.

15. The apparatus of claim 13, wherein the at least one sensor and the medical device are configured to be implanted in the patient.