Dynamic Safety Margin Algorithm for Cardiac Pacing
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Solution Overview
Problem
Current cardiac stimulation devices face challenges in maintaining effective capture and extending device longevity due to fluctuations in pacing threshold over time, which can lead to loss of capture and inefficient pacing therapy.
Innovation Solution
A safety margin algorithm that dynamically adjusts based on the historical variability of measured capture thresholds, using a rolling window to determine the appropriate safety margin for pacing pulse energy, thereby ensuring consistent capture while conserving battery life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed safety margin is used for pacing pulse energy, then capture reliability is maintained, but energy consumption increases and device longevity decreases
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed safety margin to a dynamically adjusted safety margin that adapts to changing capture threshold conditions. The safety margin is modified based on detected changes in capture threshold, allowing the system to maintain reliable capture while optimizing energy consumption according to actual physiological needs.
Solution Approach 2:
The patent implements feedback mechanisms by continuously monitoring capture threshold and using this information to adjust the safety margin. The system detects changes in capture threshold and feeds this information back to modify the pacing pulse energy configuration, creating a closed-loop control system that balances reliability and energy efficiency.
2Reliability
If pacing pulse energy is increased to ensure capture, then capture reliability improves, but battery life decreases
Solution Approach 1:
The system dynamically adjusts the safety margin component of pacing pulse energy based on detected capture threshold changes. When capture threshold is stable, a smaller safety margin is used to conserve battery life. When changes are detected, the safety margin is increased to maintain capture reliability, thus optimizing the balance between reliability and battery duration.
Solution Approach 2:
The patent changes the parameter of safety margin based on detected physiological conditions. By modifying the safety margin parameter in response to capture threshold variations, the system ensures adequate pacing energy is delivered when needed while minimizing energy consumption during stable periods, thereby extending battery life without compromising capture reliability.
3Reliability
If a larger safety margin is used, then capture is maintained during threshold fluctuations, but energy wastage increases
Solution Approach 1:
The system uses feedback from capture threshold monitoring to dynamically adjust the safety margin. Instead of using a consistently large safety margin, the system only increases it when threshold fluctuations are detected, thereby maintaining capture reliability during critical periods while minimizing energy wastage during stable periods.
Solution Approach 2:
The patent applies partial action by using a smaller safety margin than would be required for worst-case scenarios. The safety margin is sized appropriately for current conditions rather than being oversized for all conditions, reducing energy wastage while maintaining adequate capture protection when actually needed.
Data Source
AI summary
A cardiac stimulation system and associated capture management method are provided in which capture and device longevity are improved. The device determines a series of capture thresholds. Capture threshold is the minimum pulse level (pulse energy or pulse amplitude or pulse width) that captures the heart. Each determination requires delivery of pacing pulses at several (at least two) known levels (pulse energy, pulse amplitude and/or pulse width) over time. The individual determined capture thresholds are combined into a set and the variability of the set is used to set the safety margin. The greater the variability in the capture thresholds, the bigger the safety margin.