Arrhythmia detector using delta modulated turning point morphology of the ECG wave
First Claim
1. An arrhythmia detector for analyzing ECG signals obtained from a heart, said detector comprising:
- means for delta modulating an input ECG signal for obtaining a digital representation of said input ECG signal from a heart;
means for periodically classifying said digital signal as representing no slope, positive slope, or negative slope segments of said input ECG signal and respectively generating a no slope, positive slope, or negative slope signal;
means for determining, based upon a sequence over a predetermined period of time of no slope, positive slope, and negative slope signals, the amount of time an isoelectric line segment is present in said input ECG signal over said predetermined period of time; and
means for issuing a fibrillation signal when the amount of time an isoelectric line is present in said input ECG signal is less than a predetermined threshold.
1 Assignment
0 Petitions
Accused Products
Abstract
An arrhythmia detector includes a delta modulator which digitizes the ECG signal and produces a serial digital signal that represents the input ECG signal. A microprocessor classifies the signal as having no slope, positive slope, or negative slope. A finite state machine model in the microprocessor uses the positive slope, negative slope, or no slope information to determine the number of times an isoelectric line segment is present in the ECG signal. By accumulating the line-counts or number of line segments over a two-second period, a determination can be made whether the ECG signal has been in isoelectric line less than a threshold. For two out of three 2 second periods, if the percentage of isoelectric time is less than the ventricular fibrillation threshold then a ventricular fibrillation signal can be generated. For ventricular tachycardia verses supraventricular tachycardia discrimination, a second threshold which relates to the average heart rate observed in a linear formula LC(TH)=b-a*(rate)/30 can be used. If the isoelectric line-count is less than the LC(TH), then VT is declared. The regression coefficient a and b can be found by measuring the line-count and rate pairs in 2 second periods during normal sinus rhythm in periodic basis, for example, 10 data pairs every hour. The delta modulator uses a comparator which receives the ECG signal and a tracking signal to output a series of binary digits. A digital-to-analog converter generates the tracking signal.
-
Citations
18 Claims
-
1. An arrhythmia detector for analyzing ECG signals obtained from a heart, said detector comprising:
-
means for delta modulating an input ECG signal for obtaining a digital representation of said input ECG signal from a heart; means for periodically classifying said digital signal as representing no slope, positive slope, or negative slope segments of said input ECG signal and respectively generating a no slope, positive slope, or negative slope signal; means for determining, based upon a sequence over a predetermined period of time of no slope, positive slope, and negative slope signals, the amount of time an isoelectric line segment is present in said input ECG signal over said predetermined period of time; and means for issuing a fibrillation signal when the amount of time an isoelectric line is present in said input ECG signal is less than a predetermined threshold. - View Dependent Claims (2, 3, 4, 5)
-
-
6. An arrhythmia detector for detecting at lest fibrillation and tachycardia by analyzing ECG signals obtained from a heart, said detector comprising:
-
means for digitizing an input ECG signal for obtaining a digital signal representation of said input ECG signal; means for periodically classifying said digital signal representation as representing no slope, positive slope, or negative slope segments of said input ECG signal and respectively generating a no slope, positive slope, or negative slope signal; means for determining, based upon a sequence over a predetermined period of time of no slope, positive slope, and negative slope signals the amount of time an isoelectric line segment is present in said input ECG signal over said predetermined period of time, and generating an isoelectric line number corresponding to said amount of time an isoelectric line segment is present in said input ECG signal over said predetermined period of time; means for issuing and storing a preliminary fibrillation signal when the isoelectric line number fails to exceed a first threshold during said predetermined period of time such that if for any set of three consecutive predetermined periods of time at least two preliminary fibrillation signals are issued, a declaration of fibrillation is made; and means for issuing a tachycardia signal when said isoelectric line number fails to exceed a second threshold, said second threshold being greater than said first threshold during said predetermined period of time. - View Dependent Claims (7, 8, 9, 10, 11, 12)
-
-
13. An arrhythmia detector for analyzing ECG signals obtained from a heart, said detector comprising:
-
means for digitizing an input ECG signal for obtaining a digital representation of said input ECG signal; means for periodically classifying said digital signal as representing no slope, positive slope, and negative slope segments of said input ECG signal and respectively generating a no slope, positive slope, or negative slope signal; means for determining, based upon a sequence over a predetermined period of time of no slope, positive slope, or negative slope signals, the amount of time an isoelectric line segment is present in said input ECG signal over said predetermined period of time; and means for issuing a fibrillation signal when the amount of time an isoelectric line is present in said input ECG signal is less than a first predetermined threshold. - View Dependent Claims (14, 15)
-
-
16. An arrhythmia detector for detecting at least fibrillation by analyzing ECG signals obtained from a heart, said detector comprising:
-
means for digitizing an input ECG signal for obtaining a digital representation of said input ECG signal; means for periodically classifying said digital signal as representing no slope, positive slope, and negative slope segments of said input ECG signal and respectively generating a no slope, positive slope, or negative slope signal; means for determining, based upon a sequence over a predetermined period of time of no slope, positive slope, or negative slope signals the amount of time an isoelectric line segment is present in said input ECG signal over said predetermined period of time, and generating an isoelectric line number corresponding to said amount of time an isoelectric line segment is present in said input ECG signal over said predetermined period of time; and means for issuing and storing a preliminary fibrillation signal when the isoelectric line number fails to exceed a first threshold during said predetermined period of time such that if for any set of three consecutive predetermined periods of time at least two preliminary fibrillation signals are issued, a declaration of fibrillation is made. - View Dependent Claims (17, 18)
-
Specification