Heart Rate-Based CRT Pacing Without Frequent Therapy Suspension
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Solution Overview
Problem
Existing cardiac resynchronization therapy (CRT) delivery systems suspend therapy to determine the interval between atrial and ventricular events, leading to a loss of therapy and inefficient patient outcomes, as frequent suspensions disrupt the synchronization of heart ventricles.
Innovation Solution
Implementing a system that determines heart rate and selects an interval value from a stored table to control CRT delivery, reducing the frequency of therapy suspension by using anticipated values for atrial-ventricular intervals, allowing for adaptive fusion or biventricular pacing based on heart rate without continuous interruptions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If therapy is suspended to determine the current value of the interval between atrial and ventricular events, then measurement precision is improved, but productivity deteriorates due to loss of CRT pacing delivery
Solution Approach 1:
The system performs preliminary measurement of the intrinsic A-V interval during initial device operation or therapy suspension, then stores this measured value for subsequent use. This allows the device to determine pacing intervals based on stored measurements rather than continuously suspending therapy to remeasure, thereby maintaining CRT delivery while achieving accurate interval characterization.
Solution Approach 2:
The system creates a copy of the measured intrinsic A-V interval value and stores it in memory for repeated use. Instead of continuously measuring the interval by suspending therapy, the device uses the stored copy of the interval value to control pacing timing, eliminating the need for frequent therapy suspensions while maintaining accurate interval-based pacing control.
2Adaptability or versatility
If therapy suspension frequency is increased to update interval values, then adaptability is improved, but productivity deteriorates due to continuous loss of CRT pacing
Solution Approach 1:
The system implements periodic updates of the intrinsic A-V interval value at predetermined time intervals or under specific conditions (e.g., when heart rate changes significantly), rather than continuously or frequently suspending therapy. This periodic measurement approach balances the need for adaptability with the requirement to maintain continuous CRT pacing delivery for patient benefit.
3Productivity
If heart rate based interval selection is implemented, then productivity is improved by reducing therapy suspension, but measurement precision may deteriorate due to use of anticipated values
Solution Approach 1:
The system dynamically selects the appropriate intrinsic A-V interval value from multiple stored values based on the current heart rate. Different interval values are stored for different heart rate ranges, and the device automatically selects the most appropriate value based on real-time heart rate monitoring. This dynamic selection approach maintains accuracy across varying physiological conditions while avoiding continuous therapy suspension.
Data Source
AI summary
In some examples, controlling delivery of cardiac resynchronization therapy (CRT) includes storing, in a memory of an implantable medical device system and in association with each of a plurality of heart rates, at least one respective value for an interval between an atrial event and a ventricular event. Processing circuitry of the implantable medical device system may determine a heart rate of a patient and select one of the stored values for the interval between the atrial event and the ventricular event associated with the determined heart rate. The processing circuitry may further determine whether to control therapy delivery circuitry of the implantable medical device system to deliver fusion pacing or biventricular pacing, based on the selected one of the stored values for the interval between the atrial event and the ventricular event.