Automated seizure detection, quantification, warning and therapy delivery using the slope of heart rate

Abstract

A system and method for detecting seizures in a patient are disclosed. The method includes measuring at least one signal associated with the patient over a first time period, and calculating a first slope having a rate of change in a first signal of the at least one signal over the first time period. The first signal is a heart rate. The method also includes determining a difference between the first slope and a reference slope, as well as detecting an epileptic seizure based at least upon the difference between the first slope and the reference slope. Furthermore, the method includes quantifying the epileptic seizure by calculating a severity of the seizure. The severity is the product of a seizure duration and a seizure intensity.

1 . A method of detecting seizures in a patient, the method comprising:
 measuring at least one signal associated with the patient over a first time period;   calculating a first slope comprising a rate of change in a first signal of the at least one signal over the first time period, wherein the first signal is a heart rate;   determining a difference between the first slope and a reference slope;   detecting an epileptic seizure based at least upon the difference between the first slope and the reference slope; and   quantifying the epileptic seizure by calculating a severity of the seizure, wherein the severity is the product of a seizure duration and a seizure intensity, the seizure duration is the amount of time the difference between the first slope and the reference slope spent outside a threshold value, and the seizure intensity is a maximum value of the first slope during the seizure.   
     
     
         2 . The method of  claim 1 , wherein the reference slope is based upon one or more signal measurements performed under inter-ictal circumstances including at least one of physical activity, resting, high ambient temperature, daytime, and nighttime. 
     
     
         3 . The method of  claim 1 , wherein the first time period is equivalent to three heart beats of the patient. 
     
     
         4 . The method of  claim 3 , wherein the first slope is calculated by comparing a time interval between a first R wave peak and a second R wave peak with a time interval between the second R wave peak and a third R wave peak. 
     
     
         5 . The method of  claim 1 , further comprising warning at least one of the patient and a caregiver of the detection of an epileptic seizure. 
     
     
         6 . The method of  claim 1 , further comprising classifying the detected epileptic seizure. 
     
     
         7 . The method of  claim 1 , wherein each signal of the at least one signal is an autonomic signal, and is one of cardiac, vascular, respiratory, and dermal. 
     
     
         8 . A method of detecting seizures in a patient, the method comprising:
 measuring at least one signal associated with the patient over a first time period;   calculating a first slope comprising a rate of change in a first signal of the at least one signal over the first time period;   determining a difference between the first slope and a reference slope; and   detecting an epileptic seizure based at least upon the difference between the first slope and the reference slope.   
     
     
         9 . The method of  claim 8 , wherein each signal of the at least one signal is an autonomic signal including one or more of the following signals: EKG, PKG, Echocardiography, Apexcardiography (ApKG), Intra-cardiac pressure, Cardiac blood flow, cardiac thermography; heart rate (HR), change of HR, rate of change of HR, heart rate variability (HRV), change of HRV, rate of change of HRV, or HRV vs. HR. 
     
     
         10 . The method of  claim 8  or  9 , wherein the first signal is a heart rate. 
     
     
         11 . The method of  claim 10 , wherein the first time period is equivalent to three heart beats of the patient. 
     
     
         12 . The method of  claim 11 , wherein the first slope is calculated by comparing a time interval between a first R wave peak and a second R wave peak with a time interval between the second R wave peak and a third R wave peak. 
     
     
         13 . The method of  claim 8 , wherein the reference slope is based upon one or more signal measurements performed under inter-ictal circumstances including at least one of physical activity, resting, high ambient temperature, daytime, and nighttime. 
     
     
         14 . The method of  claim 8 , further comprising warning at least one of the patient and a caregiver of the detection of an epileptic seizure. 
     
     
         15 . The method of  claim 8 , further comprising quantifying the epileptic seizure by calculating a severity of the seizure, wherein the severity is the product of a seizure duration and a seizure intensity, the seizure duration is the amount of time the difference between the first slope and the reference slope spent outside a threshold value, and the seizure intensity is a maximum value of the first slope during the seizure. 
     
     
         16 . The method of  claim 15 , further comprising classifying the detected epileptic seizure in response to determining that at least one of the intensity and the duration are above the 75th percentile or below the 25th percentile of values for representative seizures. 
     
     
         17 . A medical device system for detecting seizures in a patient, comprising:
 a cardiac sensor configured to measure a heart rate of the patient over at least a first time period;   a controller configured to calculate a first slope comprising a rate of change in the heart rate over the first time period, the controller determining a difference between the first slope and a reference slope, and the controller detecting an epileptic seizure based at least upon the difference between the first slope and the reference slope.   
     
     
         18 . The medical device of  claim 17 , wherein the first time period is equivalent to three heart beats of the patient. 
     
     
         19 . The medical device of  claim 18 , wherein the first slope is calculated by comparing a time interval between a first R wave peak and a second R wave peak with a time interval between the second R wave peak and a third R wave peak. 
     
     
         20 . The medical device of  claim 17 , wherein the reference slope is based upon one or more signal measurements performed under inter-ictal circumstances including at least one of physical activity, resting, high ambient temperature, daytime, and nighttime.