CRT Optimization Using Paced Propagation Delay
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Solution Overview
Problem
Cardiac resynchronization therapy (CRT) optimization is hindered by conditions such as bundle branch block, atrio-ventricular nodal block, and atrial fibrillation, which complicate the measurement of intervals used in optimization algorithms, particularly for pacing therapies that rely on intrinsic atrio-ventricular intervals.
Innovation Solution
The implementation of a method that delivers cardiac pacing therapy with atrio-ventricular and interventricular delays, using paced propagation delays and conduction delays to determine optimized pacing parameters, even in the presence of abnormal conditions like atrial arrhythmia or conduction blocks, by measuring interventricular conduction delays and determining surrogate values for intervals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optimization algorithms rely on intrinsic atrio-ventricular intervals, then optimization accuracy is improved, but measurement reliability deteriorates in the presence of conduction blocks or atrial arrhythmia
Solution Approach 1:
The patent introduces paced propagation delay as an intermediary measurement that does not depend on intrinsic atrial activity. By pacing the atrium and measuring the delay to ventricular events, the system obtains a reliable interval measurement even when intrinsic atrial conduction is abnormal. This mediator approach allows the optimization algorithm to function reliably in patients with conduction blocks or atrial arrhythmia.
Solution Approach 2:
The patent changes the measurement parameter from intrinsic atrio-ventricular interval to paced propagation delay. This parameter substitution allows the system to measure ventricular conduction timing without relying on abnormal intrinsic atrial signals. The paced propagation delay becomes the new basis for optimization calculations, maintaining accuracy while eliminating dependence on unreliable intrinsic intervals.
2Adaptability or versatility
If pacing therapy is applied in patients with conduction blocks, then treatment coverage is improved, but optimization difficulty increases due to confounded interval measurements
Solution Approach 1:
The paced propagation delay serves as a mediator that bypasses the confounded intrinsic intervals. By introducing controlled atrial pacing and measuring the resulting ventricular response, the system obtains clean, measurable intervals that are not corrupted by conduction blocks or arrhythmias. This enables optimization algorithms to function properly in patients who would otherwise be difficult to treat.
Solution Approach 2:
The system performs preliminary atrial pacing before ventricular measurement to establish a known reference point. By controlling the atrial stimulus timing and measuring the subsequent ventricular events, the system pre-establishes a reliable measurement framework that eliminates the optimization difficulties caused by abnormal intrinsic conduction patterns.
3Device complexity
If intrinsic atrio-ventricular intervals are used for optimization, then algorithm simplicity is maintained, but measurement confounding increases with abnormal cardiac conditions
Solution Approach 1:
The patent substitutes the measurement parameter from intrinsic atrio-ventricular interval to paced propagation delay. This single parameter change maintains algorithmic simplicity while eliminating measurement confounding. The rest of the optimization algorithm can remain unchanged, as the paced propagation delay provides the same functional information as intrinsic intervals would in normal patients, but without the confounding effects of abnormal cardiac conditions.
Data Source
AI summary
An exemplary method includes delivering a cardiac pacing therapy that includes an atrio-ventricular delay and an interventricular delay, providing a paced propagation delay associated with delivery of a stimulus to a ventricle, delivering a stimulus to the ventricle, sensing an event in the other ventricle caused by the stimulus, determining an interventricular conduction delay value based on the delivering and the sensing, determining a interventricular delay (ΔSur) based on the interventricular conduction delay and the paced propagation delay and determining an atrio-ventricular delay based at least in part on the interventricular delay (ΔSur). Other exemplary methods, devices, systems, etc., are also disclosed.