T-Wave Shock Timing for ICD Defibrillation Accuracy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for determining the optimal shock strength for implantable cardioverter defibrillators (ICDs) require repeated fibrillation and defibrillation episodes, which are risky and inefficient, as they rely on probability functions rather than clear thresholds, and fail to accurately account for individual variations in cardiac vulnerability periods.
Innovation Solution
The method involves using the upper limit of vulnerability (ULV) to determine the optimal shock strength by processing multiple signals and aligning them using qualitative signal measurement techniques, allowing for precise timing of T-wave shocks based on intracardiac electrograms, thereby reducing the need for extensive testing and improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional DFT testing methods are used to determine optimal shock strength, then defibrillation effectiveness can be achieved, but the number of fibrillation episodes required increases, leading to increased risk and reduced efficiency
Solution Approach 1:
The patent applies preliminary action by measuring the ULV during the implant procedure before final ICD programming is completed. This allows the optimal shock strength to be determined in advance during a controlled implant setting rather than requiring multiple post-implant fibrillation episodes. The ULV measurement is performed as a preliminary step that establishes the defibrillation threshold parameters before the device is activated for clinical use.
2Measurement precision
If multiple fibrillation and defibrillation episodes are conducted to determine shock strength, then accurate defibrillation threshold can be established, but the procedure becomes more time-consuming and risky
Solution Approach 1:
The patent extracts the ULV measurement from the conventional DFT testing protocol that requires multiple fibrillation episodes. By isolating and measuring the ULV parameter specifically during the implant procedure using controlled electrical stimuli and T-wave timing, the method obtains accurate defibrillation threshold information without requiring repeated fibrillation-induction cycles. This extraction of the critical measurement parameter reduces both time and risk.
3Reliability
If probability-based shock strength determination is used, then defibrillation can be achieved, but individual variations in cardiac vulnerability periods are not accurately accounted for
Solution Approach 1:
The patent applies local quality by tailoring the shock timing to the individual patient's specific cardiac electrophysiology characteristics. The ULV measurement determines the precise vulnerability period for each patient by analyzing their specific T-wave morphology and electrical response to stimuli. This allows the defibrillation shock to be precisely timed relative to that individual's cardiac cycle, accounting for local variations in cardiac tissue vulnerability rather than using population-based probability approaches.
Data Source
AI summary
A method for accurately determining timing points for T-wave shocks is particularly useful in a system for determining a cardiac shock strength in an implantable cardioverter defibrillator (ICD. The method involves acquiring at least one first signal, acquiring at least a second signal, comparing the signals, and selecting a timing point with the T-wave of the signal. The first and second signals may be two different aspects of a single electrogram, first and second electrograms, or a combination thereof. Comparison preferably involves signal alignment and qualitative analysis.