METHOD AND APPARATUS FOR CARDIAC ARRHYTHMIA CLASSIFICATION USING TEMPLATE BAND-BASED MORPHOLOGY ANALYSIS
First Claim
1. A system for classifying tachyarrhythmias, the system comprising:
- a feature vector generation circuit configured to produce a template feature vector (a) using a plurality of template morphological features on a plurality of template waveforms each associated a template heart beat of a known type cardiac rhythm, an arrhythmic feature vector (b) using a plurality of arrhythmic morphological features of an arrhythmic waveform associated with an arrhythmic heart beat sensed during a tachyarrhythmia, and a maximum feature vector (a_max) and a minimum feature vector (amin) using the plurality of template morphological features, the plurality of arrhythmic morphological features, the maximum feature vector (amax) and the minimum feature vector (amin) being within a template band related to predetermined confidence levels of the plurality of template morphological features;
a correlation computing circuit coupled to the feature vector generation circuit, the correlation computing circuit configured to calculate a mean feature correlation coefficient (Fccmean) using the template feature vector (a) and the arrhythmic feature vector (b), a maximum feature correlation coefficient (Fccmax) using the maximum feature vector (amax) and the arrhythmic feature vector (b), and a minimum feature correlation coefficient (Fccmin) using the minimum feature vector (amin) and the arrhythmic feature vector (b); and
a beat classification circuit coupled to the correlation analysis circuit, the beat classification circuit configured to classify the arrthythmic heart beat using the mean feature correlation coefficient (Fccmean), the maximum feature correlation coefficient (Fccmax), the minimum feature correlation coefficient (Fccmin), and at least one predetermined correlation threshold.
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Abstract
An implantable cardioverter/defibrillator (ICD) includes a tachyarrhythmia detection and classification system that classifies tachyarrhythmias based on a morphological analysis of arrhythmic waveforms and a template waveform. Correlation coefficients each computed between morphological features of an arrhythmic waveform and morphological features of the template waveform provide for the basis for classifying the tachyarrhythmia. In one embodiment, a correlation analysis takes into account the uncertainty associated with the production of the template waveform by using a template band that includes confidence intervals.
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Citations
20 Claims
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1. A system for classifying tachyarrhythmias, the system comprising:
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a feature vector generation circuit configured to produce a template feature vector (a) using a plurality of template morphological features on a plurality of template waveforms each associated a template heart beat of a known type cardiac rhythm, an arrhythmic feature vector (b) using a plurality of arrhythmic morphological features of an arrhythmic waveform associated with an arrhythmic heart beat sensed during a tachyarrhythmia, and a maximum feature vector (a_max) and a minimum feature vector (amin) using the plurality of template morphological features, the plurality of arrhythmic morphological features, the maximum feature vector (amax) and the minimum feature vector (amin) being within a template band related to predetermined confidence levels of the plurality of template morphological features; a correlation computing circuit coupled to the feature vector generation circuit, the correlation computing circuit configured to calculate a mean feature correlation coefficient (Fccmean) using the template feature vector (a) and the arrhythmic feature vector (b), a maximum feature correlation coefficient (Fccmax) using the maximum feature vector (amax) and the arrhythmic feature vector (b), and a minimum feature correlation coefficient (Fccmin) using the minimum feature vector (amin) and the arrhythmic feature vector (b); and a beat classification circuit coupled to the correlation analysis circuit, the beat classification circuit configured to classify the arrthythmic heart beat using the mean feature correlation coefficient (Fccmean), the maximum feature correlation coefficient (Fccmax), the minimum feature correlation coefficient (Fccmin), and at least one predetermined correlation threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for classifying tachyarrhythmias, the method comprising:
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producing a template feature vector (a) and a template standard deviation vector (σ
) based on template morphological features on a plurality of template waveforms each associated with a heart beat of a known type cardiac rhythm;producing an arrhythmic feature vector (b) based on arrhythmia morphological features on an arrhythmic waveform associated with an arrhythmic heart beat sensed during a tachyarrhythmia; producing a maximum deviation vector (xmax) and a minimum deviation vector (xmin) based on at least the template feature vector (a), the arrhythmic feature vector (b), and the template standard deviation vector (σ
), the maximum deviation vector (xmax) and the minimum deviation vector (amin) indicative of morphological variations among the plurality of template morphological features;producing a maximum feature vector (amax) by adding the maximum deviation vector (xmax) to the template feature vector (g) and a minimum feature vector (amin) by adding the minimum deviation vector (xmin) to the template feature vector (a); and computing a mean feature correlation coefficient (Fccmean) based on the template feature vector (a) and the arrhythmic feature vector (b), a maximum feature correlation coefficient (Fccmax) based on the maximum feature vector (a_max) and the arrhythmic feature vector (b), and a minimum feature correlation coefficient (Fccmin) based on the minimum feature vector (amin) and the arrhythmic feature vector (b). - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification