Morphology-Based Precursor to Template Matching for ICD Rhythm Discrimination
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Solution Overview
Problem
Existing implantable cardioverter-defibrillators (ICDs) often deliver unnecessary electrical shocks due to difficulties in distinguishing between supraventricular tachycardias (SVTs), monomorphic ventricular tachycardias (VTs), and polymorphic VTs or ventricular fibrillation, which are computationally expensive to discriminate using methods like wavelet comparison.
Innovation Solution
A method and system that uses simple feature-based morphologic comparison to quickly determine if a match exists between a template beat and an episodic beat, reducing the need for detailed template matching or waveform correlation routines, thereby reducing computational expense and power consumption in ICDs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If wavelet comparison method is used to discriminate SVT from VT or monomorphic VT from polymorphic VT, then measurement precision is improved, but device complexity and computational expense increase
Solution Approach 1:
The patent segments the rhythm discrimination task into multiple stages: first performing a quick morphological filter to eliminate obvious SVTs, then applying wavelet comparison only to beats that pass the filter. This segmentation reduces overall computational complexity while maintaining accuracy for difficult cases.
Solution Approach 2:
The patent applies a preliminary morphological filter before the computationally expensive wavelet comparison. This preliminary action identifies and removes clearly SVT beats based on simple morphological criteria, so that wavelet comparison is only performed on remaining ambiguous beats, reducing total computational load.
2Measurement precision
If detailed template matching routines are performed for each beat, then measurement precision is improved, but use of energy increases
Solution Approach 1:
The patent applies partial action by performing detailed wavelet comparison only on a subset of beats that pass the preliminary morphological filter, rather than performing full analysis on all beats. This reduces total energy consumption while maintaining high accuracy for the beats that require detailed analysis.
Solution Approach 2:
The preliminary morphological filter acts as a triage mechanism that identifies beats requiring full analysis versus those that can be quickly rejected. This preliminary sorting reduces the number of energy-intensive wavelet comparisons needed, lowering overall power consumption while preserving measurement precision for critical beats.
3Measurement precision
If shifting and alignment of episode beat to template beat is performed, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent performs preliminary alignment using morphological features (peak detection, morphology-based alignment) before applying wavelet comparison. This preliminary alignment simplifies the subsequent wavelet analysis by pre-positioning the beats, reducing the computational expense of the full wavelet comparison process.
Solution Approach 2:
The alignment process is segmented into two parts: a quick morphological alignment step that uses peak and morphology features to preliminarily position beats, followed by a refined wavelet-based alignment only where needed. This segmentation reduces overall computational complexity while maintaining precision.
Data Source
AI summary
One or more embodiments of the present disclosure relates to a method and/or system for classifying and/or treating heart rhythms. The present disclosure involves sensing electrical signals associated with depolarizations of a patient's heart. The sensed electrical signals are converted to digital values and storing the digital values. Normalizing solely a maximum and a minimum value of the stored digital values associated with a depolarization of the patient's heart without normalizing other stored digital values of the depolarization is another aspect of the present disclosure. The maximum and minimum values associated with the depolarization are compared to maximum and minimum values associated with a template derived from signals indicative of a heart depolarization of known type. A determination is made as to whether a match exists between the maximum and minimum values associated with the depolarization to the maximum and minimum values associated with a template.