LV Capture Verification Algorithm for CRT Devices
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Solution Overview
Problem
Current cardiac resynchronization therapy (CRT) devices lack effective metrics for verifying left ventricular (LV) capture, leading to inadequate delivery of CRT, which can result in reduced therapeutic benefits and increased patient discomfort due to potential loss of capture.
Innovation Solution
A daily LV capture verification algorithm is integrated into CRT devices, using myocardial electrogram signals to infer capture or loss-of-capture, and providing alerts and diagnostic metrics for clinicians and patients, ensuring appropriate pacing in both ventricular chambers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If CRT devices deliver pacing stimulus to both ventricles, then cardiac resynchronization therapy is provided, but there is no effective verification that pacing capture is achieved in both ventricles
Solution Approach 1:
The patent implements a feedback mechanism by analyzing the morphology and timing of ventricular electrogram signals to determine whether pacing stimulus successfully captured each ventricle. The system continuously monitors electrogram characteristics and compares them against expected capture patterns, providing real-time verification feedback on CRT effectiveness without requiring additional hardware.
Solution Approach 2:
The patent uses the existing electrogram signal as an intermediary to infer capture status. By analyzing the electrogram's morphology, amplitude, and timing characteristics, the system indirectly determines whether pacing capture occurred in each ventricle, converting an unobservable state (capture) into measurable signal characteristics.
2Reliability
If capture verification is performed continuously, then capture status is reliably monitored, but device complexity increases
Solution Approach 1:
The patent employs self-service by utilizing the device's existing electrogram sensing and processing capabilities to perform capture verification. The same hardware components used for basic rhythm monitoring are repurposed to analyze electrogram morphology for capture detection, eliminating the need for dedicated verification hardware and reducing overall device complexity.
Solution Approach 2:
The patent makes the electrogram processing system multi-functional by using it for both basic rhythm monitoring and capture verification. The same signal processing algorithms serve dual purposes: detecting cardiac rhythms and analyzing electrogram morphology to determine pacing capture status, thereby avoiding additional specialized components.
3Measurement precision
If electrogram signal processing time is extended for accurate capture detection, then measurement precision improves, but response time increases
Solution Approach 1:
The patent applies preliminary action by pre-establishing criteria for capture detection based on electrogram morphology characteristics. The system is programmed with expected capture patterns and timing windows in advance, allowing it to quickly compare incoming electrogram signals against these predetermined standards and make rapid capture determination decisions without extensive real-time analysis.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The algorithm ensures continuous verification of LV capture, minimizing time without optimal CRT delivery, reducing patient discomfort, and enabling early identification and correction of pacing lead issues, thereby maintaining therapeutic benefits.
Implementation Method 1
pacing stimulus delivered to a second ventricular chamber induces myocardial depolarization... sensing in a first ventricle of a pacing stimulus delivered to a second ventricle
Data Source
AI summary
The present invention provides a technique for verifying pacing capture of a ventricular chamber, particularly to ensure desired delivery of a ventricular pacing regime (e.g., cardiac resynchronization therapy or “CRT”). The invention also provides for ventricular capture management by delivering a single ventricular pacing stimulus and checking inter-ventricular conduction during a temporal window to determine if the ventricular pacing stimulus captured the chamber. If a loss-of-capture (LOC) signal results from the capture management testing, then the characteristics of the applied pacing pulses are modified and the conduction test repeated. In the event that the LOC signal persists, a pacing mode-switch to an atrial-based pacing therapy and/or non-bi-ventricular pacing regimen can be implemented.