Subcutaneous ICD Paced Depolarization Template Detection
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Solution Overview
Problem
Subcutaneous implantable cardioverter defibrillators (ICDs) face challenges in accurately distinguishing between paced cardiac depolarizations and intrinsic depolarizations, leading to potential misclassification of tachyarrhythmias, especially when a patient has a separate pacemaker device, as the cardiac depolarization waveforms from pacing can differ morphologically from intrinsic waveforms.
Innovation Solution
The development of techniques for an SCD to determine paced cardiac depolarization waveform morphological templates without communicating with other IMDs, allowing it to differentiate between paced and intrinsic depolarizations, thereby improving the accuracy of tachyarrhythmia detection and avoiding false positives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the subcutaneous ICD uses traditional morphological analysis to detect tachyarrhythmias, then it can identify intrinsic depolarizations, but it misclassifies paced depolarizations as tachyarrhythmias leading to false positives
Solution Approach 1:
The patent segments the morphological analysis by creating separate templates for intrinsic depolarizations and paced depolarizations. The ICD device now maintains multiple morphological templates in memory, allowing it to distinguish between different types of depolarizations based on which template they match, thereby preventing misclassification of paced beats as tachyarrhythmias
Solution Approach 2:
The patent changes the parameter of morphological comparison by introducing a new parameter: the type of depolarization (intrinsic vs. paced). By detecting pacing artifacts and generating separate morphological templates based on this parameter, the system achieves accurate differentiation between intrinsic and paced depolarizations, resolving the false positive issue
2Measurement precision
If the subcutaneous ICD communicates with other IMDs to identify paced depolarizations, then it can accurately distinguish paced from intrinsic depolarizations, but it increases device complexity and battery drain
Solution Approach 1:
The patent enables the subcutaneous ICD to self-identify paced depolarizations by detecting pacing artifacts directly from the electrogram signals. The device autonomously generates paced morphological templates without requiring communication with external pacemakers, thus maintaining accuracy while avoiding increased device complexity and battery consumption associated with inter-device communication protocols
Data Source
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AI summary
Techniques for determining paced cardiac depolarization waveform morphological templates are described. For example, an implantable medical device (IMD) may sense a cardiac electrogram of a heart, identify cardiac depolarizations within the cardiac electrogram, and determine that the cardiac depolarizations are paced cardiac depolarizations resulting from delivery of a pacing pulse to the heart by another IMD without detecting the pacing pulse and without communicating with the other IMD. The IMD may identify paced cardiac depolarization waveforms of the paced cardiac depolarizations, determine a paced cardiac depolarization waveform morphological template based on the identified paced cardiac depolarization waveforms, determine a normal cardiac depolarization waveform morphological template based on the paced cardiac depolarization waveform morphological template, and compare the normal cardiac depolarization waveform morphological template to subsequent cardiac depolarization waveforms. The IMD may detect a cardiac tachyarrhythmia based on the above comparison.