Multi-Electrode Ventricular Sensing for PVC Detection
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Solution Overview
Problem
Existing implantable cardiac stimulating devices face challenges in reducing the risk of unintentionally triggering tachycardia or ventricular fibrillation due to the delivery of ventricular stimulating pulses and back-up pulses during vulnerable periods, particularly when premature ventricular contractions occur.
Innovation Solution
An implantable cardiac stimulating device with a multi-electrode ventricular lead and a controller that blanks the ventricular sensing unit during an atrial stimulating pulse, then activates it to detect PVCs using multiple electrode pairs, preventing ventricular stimulating pulses during vulnerable periods by leveraging the reduced propagation speed of PVC depolarization waves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single ventricular sensing channel is used, then device complexity is reduced, but PVC detection reliability deteriorates when PVCs occur during blanking periods
Solution Approach 1:
The ventricle is segmented into multiple sensing zones using three electrodes (first, second, and third electrodes), creating multiple sensing channels. Each channel independently monitors for PVCs, ensuring that if a PVC occurs during the blanking period in one zone, it can still be detected by other zones. This segmentation resolves the contradiction by maintaining simple device architecture while significantly improving PVC detection reliability through spatial distribution of sensing capabilities.
2Measurement precision
If ventricular blanking period is extended to avoid PVC undersensing, then PVC detection accuracy improves, but the risk of delivering stimulating pulses during vulnerable periods increases
Solution Approach 1:
The system performs preliminary detection of PVCs using multiple sensing channels before committing to ventricular stimulation. By having multiple independent sensing zones active during and after the blanking period, the system can identify PVCs that occur early in the blanking period and prevent subsequent stimulating pulses from being delivered during vulnerable periods. This preliminary action through multi-channel monitoring resolves the contradiction by maintaining accurate PVC detection while preventing harmful stimulations.
Solution Approach 2:
The multiple sensing channels provide continuous feedback about ventricular electrical activity throughout the blanking period and afterward. This feedback mechanism allows the control system to make informed decisions about whether to deliver stimulating pulses, adjusting the timing based on real-time detection of PVCs. The feedback from multiple zones ensures that stimulating pulses are withheld when PVCs are detected, resolving the contradiction between accurate detection and avoiding harmful effects.
3Reliability
If autocapture pacing with back-up pulses is used, then capture reliability improves, but the risk of delivering high-energy pulses during vulnerable periods increases
Solution Approach 1:
The system performs preliminary detection of PVCs using multiple sensing channels before delivering back-up pulses. By monitoring multiple ventricular zones throughout the blanking period and afterward, the system can identify PVCs that would make the heart vulnerable to high-energy stimulation. This preliminary detection action allows the system to withhold back-up pulses when PVCs are detected, resolving the contradiction between ensuring capture reliability and preventing harmful effects from high-energy pulses during vulnerable periods.
Data Source
AI summary
An implantable medical device, IMD, comprises atrial and ventricular sensing units for sensing atrial or ventricular electric events. The IMD also comprises atrial and ventricular pulse generators for generating atrial or ventricular pacing pulses. The ventricular sensing unit is connectable to a multi-electrode lead to individually sense electric events in a ventricle using multiple electrode pairs implanted at different ventricular sites. A controller blanks the ventricular sensing unit during a blanking period following delivery of an atrial stimulating pulse by the atrial pulse generator and activates the ventricular sensing unit at the expiry of the blanking period. Due to the lower propagation speed of PVC depolarization waves and the multi-site sensing, a PVC depolarization wave initiated at a ventricular site during the blanking period can be detected by the IMD.