Anti-Tachycardia Pacing Timing for T-Wave Alternans
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Solution Overview
Problem
Existing implantable medical devices (IMDs) face challenges in effectively delivering anti-tachycardia pacing (ATP) in the presence of T-wave alternans (TWA), as the timing of the excitable gap for myocardial capture is variable due to TWA, potentially reducing the effectiveness of ATP pulses in terminating ventricular tachycardia.
Innovation Solution
The medical device employs a sensing circuit to detect T-wave alternans and adjusts the alternating ATP time intervals to align with the varying excitable gap, ensuring ATP pulses are delivered during optimal myocardial excitation phases, even in the presence of TWA.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fixed ATP time intervals are used for delivering anti-tachycardia pacing pulses, then the device operation is simple, but the effectiveness of ATP is reduced in the presence of T-wave alternans due to variable excitable gap timing
Solution Approach 1:
The patent implements dynamic adjustment of ATP pulse timing intervals based on detected T-wave alternans patterns. The control circuit modifies the time intervals between consecutive ATP pulses to alternate between longer and shorter intervals, synchronizing with the alternating phases of the excitable gap caused by TWA. This dynamic timing adaptation ensures optimal myocardial capture during varying excitable gap periods, resolving the contradiction between maintaining simple operation and achieving reliable therapy effectiveness.
Solution Approach 2:
The patent changes the temporal parameter of ATP pulse delivery by introducing alternating time intervals in response to detected T-wave alternans. When TWA is detected, the system transitions from fixed to variable inter-pulse intervals, adjusting the timing parameter to match the alternating excitable gap phases. This parameter modification enables effective ATP delivery despite the variable myocardial excitability, improving reliability without excessive complexity.
2Reliability
If ATP pulses are delivered at standard intervals, then the device complexity is low, but the ATP pulses may miss the excitable gap in the presence of TWA, reducing therapy effectiveness
Solution Approach 1:
The patent employs feedback control by continuously monitoring cardiac electrical signals to detect T-wave alternans patterns. The control circuit uses this feedback information to dynamically adjust the timing of subsequent ATP pulses, alternating between longer and shorter intervals based on the detected TWA phase. This feedback mechanism ensures ATP pulses are delivered during optimal excitable gap periods, maintaining ease of operation while significantly improving myocardial capture effectiveness.
Solution Approach 2:
The patent performs preliminary detection of T-wave alternans before initiating or continuing ATP delivery. By detecting the alternating T-wave patterns in advance, the system can pre-calculate and prepare the appropriate alternating time intervals for ATP pulse delivery. This preliminary action ensures that when ATP pulses are delivered, they are synchronized with the excitable gap phases, improving capture effectiveness without complicating the actual pulse delivery operation.
Data Source
AI summary
A medical device is configured to deliver anti-tachycardia pacing (ATP) in the presence of T-wave alternans. The device is configured to detect a ventricular tachyarrhythmia from a cardiac electrical signal received by the medical device. In response to the detected ventricular tachyarrhythmia, the device delivers a plurality of ATP pulses at alternating time intervals. The alternating time intervals comprise at least a first ATP time interval separating a first pair of the ATP pulses and a second ATP time interval different than the first ATP time interval. The second ATP time interval consecutively follows the first ATP time interval and separates a second pair of the ATP pulses.