Dual-Threshold Cardiac Event Verification for Under-Sensed PVCs
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Solution Overview
Problem
Medical devices often incorrectly detect bradycardia or asystole episodes due to under-sensing of cardiac events, particularly premature ventricular contractions (PVCs) with wide QRS complexes or high amplitudes, leading to inappropriate therapy delivery and diagnosis.
Innovation Solution
A method and system that utilize a primary and secondary sensing channel with adjustable thresholds to detect and verify cardiac events, where the primary channel senses events based on a primary threshold and the secondary channel detects under-sensed events using a secondary threshold, thereby confirming or rejecting the detection of bradycardia or asystole episodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a primary threshold is used to sense cardiac events, then the detection of normal cardiac events is achieved, but under-sensing of PVCs with wide QRS complexes or high amplitudes occurs
Solution Approach 1:
The sensing system is divided into multiple independent sensing channels, each with its own threshold. The first sensing channel uses a primary threshold for normal events, while the second sensing channel uses a secondary threshold specifically for detecting PVCs. This segmentation allows each channel to be optimized for different event types without interfering with each other's performance.
Solution Approach 2:
The patent adds an additional dimension to the sensing system by introducing a second sensing channel with a different threshold level. Instead of trying to make a single threshold work for all events, the system creates a multi-dimensional sensing approach where events can be detected along different threshold dimensions, ensuring both normal events and PVCs are reliably captured.
2Device complexity
If a single sensing threshold is used, then the device complexity is minimized, but inappropriate detection of bradycardia and asystole episodes occurs
Solution Approach 1:
The sensing function is segmented across multiple channels with different thresholds. The first channel handles normal event detection while the second channel handles PVC detection. This segmentation enables accurate arrhythmia detection by ensuring PVCs are not missed, which would otherwise lead to false bradycardia or asystole diagnoses.
Solution Approach 2:
The second sensing channel acts as an intermediary mechanism to verify events that might be missed by the first channel. By providing an additional sensing pathway with a different threshold, the system mediates between the risk of missing PVCs and the complexity of implementing multiple sensing systems.
3Reliability
If the primary threshold is adjusted to detect PVCs, then under-sensing of PVCs is reduced, but normal cardiac events may be under-sensed
Solution Approach 1:
The patent segments the detection task by assigning different thresholds to different sensing channels. The first channel maintains a threshold optimized for normal events, while the second channel uses a lower threshold optimized for detecting PVCs. This segmentation allows each channel to perform its specialized function without compromising the other.
Solution Approach 2:
Each sensing channel is given local quality optimized for its specific detection target. The first channel has sensing characteristics suited for normal cardiac events, while the second channel has characteristics suited for detecting the abnormal morphology of PVCs. This local optimization ensures high reliability for each event type without requiring compromise.
Data Source
AI summary
A system and method for detecting and verifying bradycardia/asystole episodes includes sensing an electrogram (EGM) signal. The EGM signal is compared to a primary threshold to sense events in the EGM signal, and at least one of a bradycardia or an asystole is detected based on the comparison. In response to detecting at least one of a bradycardia or an asystole, the EGM signal is compared to a secondary threshold to sense events under-sensed by the primary threshold. The validity of the bradycardia or the asystole is determined based on the detected under-sensed events.