Implantable Device Modulating AV Delay via Autonomic Feedback
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Solution Overview
Problem
Current implantable medical devices using atrial-based pacing modes face challenges in maintaining optimal ventricular-atrial delay, leading to potential retrograde blood flow and diminished cardiac output due to inadequate adjustment of ventricular timing in response to increased heart rates, which can result in hemodynamic compromise and adverse symptoms.
Innovation Solution
An implantable medical device with ventricular sensing capabilities, capable of modulating the atrial-ventricular (AV) delay by using physiological sensors to define upper and lower bounds, adjusting pacing parameters to maintain AV delay within a normal range, and employing rate-responsive pacing to prevent atrial contraction against a closed valve, thereby ensuring proper cardiac output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the atrial pacing rate is elevated to increase cardiac output, then the heart rate increases, but the AV delay is not shortened and may be elongated, causing VA delay to become too short and resulting in retrograde blood flow and diminished cardiac output
Solution Approach 1:
The patent implements a feedback mechanism where the implantable medical device continuously monitors the AV delay and VA interval in real-time. When the VA interval becomes too short or the AV delay exceeds predetermined bounds, the device automatically adjusts the atrial pacing rate or AV delay to restore optimal timing relationships, preventing retrograde blood flow and ensuring effective cardiac output
Solution Approach 2:
The patent employs dynamic adjustment of pacing parameters based on real-time physiological conditions. The device modifies the atrial pacing rate and AV delay dynamically in response to changing cardiac demands and AV nodal conduction characteristics, allowing the system to adapt to varying metabolic requirements while maintaining optimal ventricular-atrial timing
2Productivity
If the atrial pacing rate is increased to meet metabolic demand, then the heart rate rises, but the effective ventricular rate may actually decrease due to Wenckebach block
Solution Approach 1:
The device monitors ventricular response to atrial pacing and detects Wenckebach block patterns. When conduction abnormalities are detected, the system provides feedback to adjust the atrial pacing rate or AV delay to maintain effective ventricular rate, ensuring that increases in atrial rate translate to proportional increases in ventricular rate
Solution Approach 2:
The patent implements preliminary detection and correction of conduction abnormalities. By monitoring AV delay trends and detecting early signs of Wenckebach block before they significantly impact ventricular rate, the device can preemptively adjust pacing parameters to prevent effective ventricular rate deterioration
3Productivity
If the VA delay becomes too short over prolonged period, then the atrial contraction occurs against a contracted ventricle, but maintaining higher heart rate is needed to increase cardiac output
Solution Approach 1:
The device continuously monitors VA interval and provides feedback control to prevent it from becoming too short. When the VA interval approaches harmful thresholds, the system automatically extends the AV delay or reduces the atrial pacing rate to ensure adequate ventricular relaxation time, preventing retrograde blood flow while minimizing impact on cardiac output
Solution Approach 2:
The patent implements preliminary protective measures by setting predetermined bounds for AV delay and VA interval. Before harmful conditions develop, the system preemptively adjusts pacing parameters to keep the VA interval within safe ranges, preventing retrograde blood flow and atrial contraction against closed valves
Data Source
AI summary
An implantable medical device and associated method provide atrial pacing and measure an atrial ventricular (AV) delay. An autonomic function index is computed using the AV delay. The autonomic function index may be compiled in a medical report. In some embodiments, the autonomic function index is used to adjust atrial pacing control parameters.