Active Electrical System Post-Shock Stimulation Control
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Solution Overview
Problem
Conventional subcutaneous ICD systems face limitations in sensing intrinsic cardiac signals post-shock due to afterpotentials from high-intensity stimuli, leading to reduced hemodynamic output and potential misdelivery of stimuli.
Innovation Solution
An active electrical system with implantable components and an external programming unit, featuring a pulse delivery unit, sensing unit, and algorithm for classifying cardiac signals. The system operates in two modes: one for delivering pulses at high repetition rates and another for delivering a maximum number of pulses at lower rates, with the control unit switching between modes based on signal classification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a blanking window is extended to prevent afterpotential interference, then sensing reliability is improved, but the maximum stimulation rate is limited and hemodynamic output is reduced
Solution Approach 1:
The patent divides the post-shock period into distinct time windows: a first time window with a longer blanking period for reliable sensing, and a second time window with a shorter blanking period for higher stimulation rates. This segmentation allows the system to optimize sensing reliability when needed while enabling higher productivity when afterpotentials have decayed
Solution Approach 2:
The patent dynamically adjusts the blanking window duration based on the detected cardiac cycle phase and timing relative to the shock delivery. The blanking period is adaptively shortened or extended depending on whether the system is in the first or second time window, allowing optimal balance between sensing reliability and stimulation rate at different moments
2Power
If high-intensity stimuli are delivered to ensure hemodynamic output, then stimulation effectiveness is improved, but afterpotentials increase and interfere with signal sensing
Solution Approach 1:
The patent acknowledges that high-intensity stimuli generate afterpotentials that can interfere with sensing, but converts this harmful effect into a beneficial timing strategy. By delivering stimuli in the second time window when the system is configured to handle afterpotential periods, the high-intensity stimulation achieves hemodynamic effectiveness while the structured time windows manage the inevitable afterpotential interference
3Measurement precision
If sensing is performed continuously to detect intrinsic heart signals, then detection capability is improved, but false detection of intrinsic signals occurs due to afterpotentials
Solution Approach 1:
The patent applies preliminary action by pre-configuring different blanking window settings for the first and second time windows before sensing occurs. The system prepares appropriate sensing parameters in advance for each time window, ensuring that when sensing is performed, the correct parameters are already in place to distinguish true intrinsic signals from afterpotential artifacts
Data Source
AI summary
An active electrical system comprising implantable components and an external programming unit, the system further comprising an algorithm for classifying the sensed electrical cardiac signals, and a control unit configured to drive the pulse delivery unit in a first mode to deliver a predetermined number of pulses at repetition rates greater than or equal to a threshold value, and to drive the pulse delivery unit in a second mode to deliver a predetermined maximum number of pulses at repetition rates below the threshold value, and wherein the control unit in the second mode is configured to switch to the first mode or terminate pulse delivery depending on a classification result of the algorithm.