Cardiac Resynchronization Device Capture Verification
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Solution Overview
Problem
Current cardiac pacing systems face challenges in effectively verifying and maintaining capture of the left ventricle during cardiac resynchronization therapy (CRT), leading to ineffective or deleterious therapy delivery due to factors like varying capture thresholds, electrode migration, and conduction delays, which can result in patients not receiving the full benefits of CRT.
Innovation Solution
The solution employs a method that uses inter-ventricular conduction evidence to infer capture or loss-of-capture of pacing stimuli, comparing time intervals from pacing stimulus delivery to intrinsic responses, and adjusts stimulus output based on heart rate, activity, and other physiological factors to ensure continuous verification and adjustment of pacing capture in both ventricles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If continuous capture verification is implemented in CRT devices, then reliability of therapy delivery is improved, but device complexity increases
Solution Approach 1:
The system uses its own pacing stimulus and intrinsic cardiac responses to verify capture, eliminating the need for external verification equipment. The device paces the ventricle and monitors for the expected evoked response, allowing self-verification of capture status
Solution Approach 2:
The system continuously monitors intrinsic cardiac responses following pacing stimuli and uses this feedback to determine capture status. The sensed ventricular events are compared against expected timing windows to provide real-time feedback on capture effectiveness
2Measurement precision
If capture verification is performed continuously, then capture detection accuracy is improved, but processing time increases
Solution Approach 1:
The system pre-defines capture detection windows based on expected physiological timing of ventricular depolarization. By establishing these time windows in advance, the device can quickly determine capture status without performing complex real-time analysis
Solution Approach 2:
Capture verification is performed at regular pacing intervals rather than continuously monitoring every electrical event. The system checks for capture at specific predetermined times following each pacing stimulus, reducing overall processing requirements
3Adaptability or versatility
If stimulus output is adjusted dynamically, then adaptability to varying capture thresholds is improved, but device complexity increases
Solution Approach 1:
The pacing stimulus output is made dynamic rather than fixed, allowing automatic adjustment of amplitude and duration based on detected capture status. The system can increase or decrease stimulus parameters in response to changing capture thresholds without manual intervention
Solution Approach 2:
The system changes pacing parameters (amplitude, pulse width) based on detected capture status and physiological conditions. By modifying these parameters dynamically, the device adapts to varying capture thresholds while maintaining effective capture
Data Source
AI summary
In bi-ventricular pacing devices (including CRT devices) analysis of myocardial electrogram signals in one ventricle (e.g., a left ventricle, or “LV”) can be used to infer capture or loss-of-capture (LOC) of an earlier stimulus pulse in the same ventricle, on a continuous (every pacing cycle), triggered, aperiodic and/or periodic basis. Rather than using an evoked-response principle as has been the basis of capture detection in prior art and other systems, a principle employed via the present invention uses evidence of inter-ventricular conduction (i.e., from the opposite chamber) and/or atrio-ventricular conduction as evidence of LOC, since a non-capturing pacing stimulus provided to a first chamber will allow the myocardial tissue of the first chamber to remain non-refractory and thus inter-ventricular and atrio-ventricular wavefront propagation and conduction can commence and be detected thereby revealing whether LOC has occurred.