System and method for complexity analysis-based cardiac tachyarrhythmia detection
First Claim
1. A system for detecting cardiac arrhythmia comprising:
- a sensor that senses an intrinsic signal indicative of cardiac activity;
a signal processor receiving said intrinsic signal and transforming said intrinsic signal into a sequence S indicative of non-linear characteristics of said cardiac activity;
a calculator arranged to operate on said signal S to determine a complexity measure CM indicative of the complexity of a dynamic behavior of said cardiac activity; and
a complexity analyzer that analyzes said complexity measure CM to derive a current condition of the heart and generates a corresponding output, wherein said complexity analyzer includes a first comparator that compares said complexity measure CM to a first threshold TDR to detect a non-shockable rhythm and a second comparator that compares said complexity measure CM to a second threshold HCT to detect a high frequency noise;
said complexity analyzer being adapted to distinguish between cardiac classifications of the heart including a nonshockable rhythm, ventricular tachycardia and ventricular fibrillation.
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Abstract
A system and method based on electrocardiogram (ECG) complexity analysis for real-time detecting shockable ventricular fibrillation (VF) and ventricular tachycardia (VT), and discriminating them from non-shockable tachyarrhythmia (e.g. supraventricular tachycardia (SVT) and atrial fibrillation (AF)) and high-frequency noise. In the disclosed invention, complexity measure CM (0 to 100), quantitatively characterizing the complexity nature of the non-linear dynamics underlying cardiac arrhythmia, is extracted from the sensed patient ECG signal using ECG complexity analysis. From the calculated complexity measure, by three thresholds (low complexity threshold (LCT), mediate complexity threshold (MCT), and high complexity threshold (HCT)), different kinds of tachyarrhythmia (i.e. heart rate (HR) above a preset rate threshold) and high-frequency noise are discriminated from each other: for non-shockable tachyarrhythmia, CM≦LCT; for VT, LCT<CM≦MCT; for VF, MCT<CM≦HCT; and for high-frequency noise, HCT<CM. The disclosed system and method can be used as a primary cardiac tachyarrhythmia detection scheme or as a backup system to reconfirm arrhythmia detection using conventional techniques.
81 Citations
31 Claims
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1. A system for detecting cardiac arrhythmia comprising:
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a sensor that senses an intrinsic signal indicative of cardiac activity;
a signal processor receiving said intrinsic signal and transforming said intrinsic signal into a sequence S indicative of non-linear characteristics of said cardiac activity;
a calculator arranged to operate on said signal S to determine a complexity measure CM indicative of the complexity of a dynamic behavior of said cardiac activity; and
a complexity analyzer that analyzes said complexity measure CM to derive a current condition of the heart and generates a corresponding output, wherein said complexity analyzer includes a first comparator that compares said complexity measure CM to a first threshold TDR to detect a non-shockable rhythm and a second comparator that compares said complexity measure CM to a second threshold HCT to detect a high frequency noise;
said complexity analyzer being adapted to distinguish between cardiac classifications of the heart including a nonshockable rhythm, ventricular tachycardia and ventricular fibrillation. - View Dependent Claims (2, 3, 4, 5, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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6. The system of 5 claim wherein said normalizer is adapted to normalize said count to limit said complexity measure to a predetermined range.
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24. A device for applying antitachyarrhythmic therapy to a patient'"'"'s heart comprising:
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a sensor that senses an intrinsic signal indicative of cardiac activity of the patient, said cardiac activity exhibiting a non-linear dynamic behavior;
a complexity calculator adapted to determine a complexity measure indicative of the complexity of said intrinsic signal;
a complexity analyzer adapted to analyze the condition of the heart by determining if said complexity measure CM is characteristic of treatable and non-shockable tachyarrhythmia, wherein said complexity analyzer includes a first comparator that compares said complexity measure CM to a first threshold TDR to detect a non-shockable tachyarrhythmia and a second comparator that compares said complexity measure CM to a second threshold HCT to detect a high frequency noise;
a conventional cardiac detector adapted to generate a cardiac signal using conventional techniques; and
a controller adapted to receive said CM and said cardiac signal and to generate commands defining cardiac therapy based on both said CM and said cardiac signal if said CM is in a range characteristic of treatable tachyarrhythmia. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31)
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Specification