Identifying seizures using heart rate decrease

• US 8,725,239 B2
• Filed: 04/25/2011
• Issued: 05/13/2014
• Est. Priority Date: 04/25/2011
• Status: Active Grant

• Current Assignee: LivaNova USA, Inc. (LivaNova Plc)
• Original Assignee: Cyberonics, Inc
• Inventors: Liao, Wangcai
• Primary Examiner(s): MANUEL, GEORGE C
• Application Number:
  US13/093,475
• Publication Number:
  US 20120271181A1
• Time in Patent Office: 1,114 Days
• Field of Search: 600/509, 600/9.509
• US Class Current: 600/509
• 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 5/02405 Determining heart rate variability
• CPC Class Codes: A61B 5/02438 with portable devices, e.g. worn by the patient
• CPC Class Codes: A61B 5/0245 by using sensing means generating electric signals, i.e. ECG signals
• CPC Class Codes: A61B 5/4094 Diagnosing or monitoring seizure diseases, e.g. epilepsy
• CPC Class Codes: A61B 5/7282 Event detection, e.g. detecting unique waveforms indicative of a medical condition A61B5/4094, A61B5/4818, A61B5/349, A61B5/0823 take precedence

Abstract

Methods and systems for detecting a seizure event, including receiving heart beat data versus time for a patient, detecting an increase in the heart rate of a patient from a baseline heart rate to an elevated heart rate, detecting a decrease in heart rate from the elevated heart rate, for a time interval occurring during said decrease in heart rate, determining at least one of a) a rate of decrease in heart rate and b) a rate of change in a rate of decrease in heart rate, and detecting a seizure event in response to determining at least one of a) a rate of decrease in heart rate greater than a threshold rate of decrease, and b) a rate of change in the rate of decrease less than a threshold rate of change in a rate of decrease.

Claims

1. A method for detecting a seizure event, the method comprising:

receiving heart beat data versus time for a patient;

detecting an increase in a heart rate of the patient based on the heart rate data from a baseline heart rate to an elevated heart rate;

detecting a decrease in heart rate from the elevated heart rate;

for a time interval occurring during said decrease in heart rate, determining at least one of a) a rate of change of the decrease in heart rate and b) a rate of change in a rate of decrease in heart rate; and

determining occurrence of a seizure event in response to the rate of change of the decrease in heart rate satisfying a threshold rate.

2. The method of claim 1, wherein the rate of change of the decrease in heart rate at the time satifies the threshold rate when the rate of change of the decrease in heart rate at the time is greater than the threshold rate, and wherein the threshold rate in based on a non-seizure event.

3. The method of claim 1, further comprising:

determining a rate of change of the rate of change of the decrease in her heart rate at the time; and

confirming the occurrence of the seizure event when the rate of change of the rate of change of the decrease in heart rate at the time satisfies a second threshold.

4. The method of claim 3, wherein the second threshold is satisfied when the rate of change in the rate of change of the decrease in heart rate at the time is greater than the second threshold, and wherein the second threshold is based on a non-pathological event.

5. The method of claim 1, further comprising:

determining an initial detection of a seizure event based upon the increase in heart rate;

determining a profile of the decrease in heart rate;

comparing the profile of the decrease in heart rate to a known profile of a seizure event decrease in heart rate; and

confirming the occurrence of the seizure event in response to determining that the profile of the decrease in heart rate is substantially similar to the known profile of the seizure event decrease in heart rate.

6. The method of claim 1, further comprising:

determining a profile of the rate of change of decrease in heart rate;

comparing the profile of the rate of change of decrease in heart rate to a known profile of a nonpathologic rate of change of decrease in heart rate; and

confirming the detection of the seizure event in response to determining that the profile of the rate of change of decrease in heart rate is substantially dissimilar to the known profile of the nonpathologic rate of change of decrease in heart rate.

7. The method of claim 6, wherein the known profile of the nonpathologic rate of change of decrease in heart rate is at least one of:

an asymptotically decreasing profile, an exponentially decreasing profile, or a concave decreasing profile.

8. The method of claim 1, further comprising:

determining a first average rate of change of heart rate over a first time interval;

determining a second average rate of change of heart rate over a second time interval, wherein the second time interval is different from the first time interval; and

confirming the occurrence of the seizure event in response to determining that the first average rate of change of heart rate is substantially equal to the second average rate of change of heart rate.

9. The method of claim 1, wherein the elevated heart rate is a particular rate of at least one of 10 beats per minute greater than the baseline heart rate or 10 percent greater than the baseline heart rate.

10. A system for detecting a seizure event in a patient, the system comprising:

one or more processors; and

one or more memory units coupled to the one or more processors;

the one or more processors configured to;

receive data of heart beat versus time for a patient;

detect an increase in a heart rate from a baseline heart rate to an elevated heart rate;

detect a decrease in heart rate from the elevated heart rate for a time interval occurring during said decrease in heart rate,

determine a first average rate of change of decrease in heart rate over a first time interval;

determine a second average rate of change of decrease in heart rate over a second time interval, wherein the second time interval is different from the first time interval; and

indicate occurrence of detect a seizure event in response to determining at least one of a) that a rate of decrease in heart rate is greater than a threshold rate of decrease, and b) that the rate of change in the rate of decrease is less than a threshold rate of change in a rate of decrease the first average rate of change of decrease in heart rate being within a particular percentage of the second average rate of change of decrease in heart rate.

11. The system of claim 10, wherein the one or more processors are further comprising to:

determine a rate of change in heart rate at a particular time; and

confirm the occurrence of the seizure event when the rate of change in heart rate at the particular time satifies a threshold,

comprising a first intermediate heart rate and a second intermediate heart rate, wherein said first intermediate heart rate is a heart rate between said elevated heart rate and said baseline heart rate and occurring during said decrease in heart rate from the elevated heart rate, and wherein said second intermediate heart rate is a heart rate between said first intermediate heart rate and said baseline heart rate and occurring during said decrease in heart rate from the elevated heart rate, wherein the system being configured to identify the seizure event comprises the system being configured to detect the seizure event in response to determining at least one of a) that a rate of decrease in heart rate from said first intermediate heart rate to said second intermediate heart rate is greater than a threshold rate of decrease, and b) that a rate of change in a rate of decrease in heart rate from first intermediate heart rate to said second intermediate heart rate is less than a threshold rate of change in a rate of decrease.

12. The system of claim 10, where the one or more processors are further configured to:

determine a profile of the decrease in heart rate;

compare the profile of the decrease in heart rate to a known profile of a nonpathological decrease in heart rate; and

confirm the occurrence of the seizure event in response to determining that the profile of the decrease in heart rate is substantially dissimilar to the known profile.

13. The system of claim 10, where the one or more processors are further configured to:

determine a profile of the decrease in heart rate;

compare the profile of the decrease in heart rate to a known profile of a seizure event decrease in heart rate; and

confirm the occurrence of the seizure event in response to determining that the profile of the decrease in heart rate is substantially similar to the known profile of the seizure event decrease in heart rate.

14. The system of claim 13, wherein the known profile of the seizure event decrease in heart rate is substantially a linearly decreasing profile.

15. The system of claim 10, where the one or more processors are further configured to:

determine a rate of change in a rate of a rate of change in heart rate at a particular time; and

confirm the occurrence of the seizure event when the rate of change in the rate of change in heart rate at the particular time satisfies a second threshold,

determine a first average decreasing heart rate over a first interval occurring during said decrease in heart rate;

determine a second average decreasing heart rate over a second interval occurring during said decrease in heart rate, wherein the second interval is different from the first interval; and

confirm the detection of the seizure event in response to determining that the first average decreasing heart rate is substantially equal to the second average decreasing heart rate.

16. A computer program product embodied in a computer-operable medium, the computer program product comprising logic instructions, the logic instructions executable to:

process data of heart rate versus time for a patient to detect an increase in the heart rate of the patient from a baseline heart rate to an elevated heart rate;

detect a decrease in heart rate from the elevated heart rate;

for a time interval occurring during said decrease in heart rate, determine at least one of a) a rate of decrease in heart rate and b) a rate of change in a rate of decrease in heart rate; and

indicate occurrence of a seizure event in response to determining the rate of change in the rate of decrease satisfies a threshold.

17. The product of claim 16, the logic instructions being further executable to:

determine a first average heart rate over a first time interval;

determine a second average heart rate over a second time interval, wherein the second time interval is different from the first time interval; and

receive heart beat data versus time for a patient;

detect an increase in the heart rate of the patient from a baseline heart rate to an elevated heart rate;

detect a decrease in heart rate from the elevated rate to a first intermediate rate between the elevated rate and the baseline rate, and further

detecting a decrease in heart rate to a second intermediate rate between the first intermediate rate and the baseline rate;

determine at least one of a) a rate of decrease from said first intermediate rate to said second intermediate rate and b) a rate of change in a rate of decrease in heart rate from said first intermediate rate to said second intermediate rate; and

confirm the occurrence of the seizure event in response to the first average heart rate being within a particular perecentage of the second average heart rate.

18. The product of claim 16, wherein the elevated heart rate is a rate at least a specified threshold above the baseline heart rate.

19. The product of claim 16, wherein the threshold is satisfied when the rate of change in the rate of decrease is less than the threshold, and wherein the threshold is based on a non-seizure event.

20. The product of claim 16, wherein the baseline heart rate is determined as a statistical measure of central tendency of heart rate during a time window,

detect a seizure event based on an increase in heart rate from a baseline heart rate to an intermediate elevated heart rate between the elevated heart rate and the baseline heart rate;

and

detect a seizure event in response to determining at least one of that the rate of decrease of heart rate from said first intermediate rate to said second intermediate rate is greater than a threshold rate of decrease and the rate of change in the rate of decrease from said first intermediate rate to said second intermediate rate is less than a threshold rate of change in a rate of decrease comprises confirming said detecting a seizure event based on an increase in heart rate.