Far-Field Electrogram Oversensing Detection
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Solution Overview
Problem
Implantable medical devices (IMDs) face challenges in accurately detecting cardiac events due to lead-related conditions, electromagnetic interference, and noise sources, leading to false detection of cardiac events, which can result in inappropriate therapy delivery and potential harm to patients.
Innovation Solution
The use of far-field electrograms (FFEGMs) to identify oversensed cardiac events by comparing characteristics with near-field electrograms (NFEGMs), allowing for the differentiation between actual cardiac events and noise-induced artifacts, and implementing remediation techniques such as multi-vector pacing and impedance monitoring to ensure accurate therapy delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If single-sense electrode configuration is used for cardiac event detection, then device complexity is reduced, but measurement precision deteriorates due to inability to differentiate oversensed events from actual cardiac events
Solution Approach 1:
The sensing function is segmented into two independent electrode configurations: a first sense electrode configuration for detecting cardiac events and a second sense electrode configuration for verifying detected events. This segmentation allows the system to cross-validate signals and differentiate between actual cardiac events and oversensed events, thereby improving detection accuracy without requiring a complete redesign of the sensing system.
Solution Approach 2:
The second sense electrode configuration acts as an intermediary verification mechanism. When the first sense electrode configuration detects a cardiac event, the system uses the second sense electrode configuration to verify whether the detected signal corresponds to a real cardiac event or is an artifact. This intermediary checking process resolves the contradiction by providing additional validation without significantly increasing overall system complexity.
2Reliability
If lead-related conditions and noise sources are present, then sensing integrity is compromised, but adding verification mechanisms increases device complexity
Solution Approach 1:
The system merges the sensing and verification functions into a single integrated sensing system that uses two electrode configurations working in conjunction. Rather than adding a separate complex verification system, the patent combines both sensing and verification capabilities within the same implantable medical device, sharing common circuitry and processing resources. This merging approach improves sensing integrity by providing cross-validation while minimizing the increase in device complexity through resource sharing.
3Reliability
If far-field electrogram verification is implemented, then inappropriate therapy delivery is reduced, but loss of time occurs in verifying cardiac events
Solution Approach 1:
The system performs preliminary verification by continuously monitoring signals from both sense electrode configurations simultaneously. Rather than waiting to verify after a detection is made, the system has both sensing channels ready and comparing signals in real-time. This preliminary action approach allows the system to quickly determine whether a detected event is valid without requiring extensive post-detection analysis, thereby reducing the time loss associated with verification while maintaining high therapy delivery accuracy.
Data Source
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AI summary
In general, the disclosure is directed to techniques for identification and remediation of oversensed cardiac events using far-field electrograms (FFEGMs). Identification of oversensed cardiac events can be used in an ICD to prevent ventricular fibrillation (VF) detection, and thereby avoid delivery of an unnecessary defibrillation shock. Alternatively, or additionally, identification of oversensed cardiac events can be used in an ICD to support delivery of bradycardia pacing during an oversensing condition. In some cases, bradycardia pacing delivered in response to detection of oversensed cardiac events may include pacing pulses from multiple vectors to provide redundancy in the event the oversensing may be due to a lead-related condition.