Cardiac Capture Testing via Vectorogram Analysis
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Solution Overview
Problem
Conventional capture test techniques for active implantable medical devices are prone to false positives and negatives due to atypical situations, leading to erroneous readjustment of stimulation energy, and are inefficient in multisite devices, where each site requires separate testing, increasing the duration of the capture test.
Innovation Solution
The solution involves analyzing endocavitary electrogram signals from two distinct channels to detect the evoked wave using a two-dimensional vectorogram analysis, determining non-temporal characteristics and descriptor parameters to accurately determine capture or loss of capture, allowing for cycle-by-cycle adjustment of stimulation energy and intervals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional capture test techniques are used at regular intervals, then the device operates with stable energy settings, but the tests are deceived by atypical situations leading to false positives and negatives
Solution Approach 1:
The patent transitions from analyzing single-channel EGM signals to using two-dimensional vectorogram analysis combining unipolar and bipolar signals. This dimensional expansion enables more accurate discrimination between true capture events and atypical situations like fusion beats, directly resolving the contradiction between test reliability and measurement precision by providing additional analytical dimensions.
Solution Approach 2:
The invention changes the analytical parameters from temporal-only analysis to combined spatial-temporal analysis using vectorogram descriptors. By extracting geometric features (area, orientation, shape) from the 2D vectorogram representation, the system achieves more reliable capture detection that is resistant to atypical rhythm variations, thereby improving both reliability and measurement precision.
2Speed
If capture tests are performed continuously cycle-by-cycle, then the device reacts quickly to capture losses, but it becomes very sensitive to atypical cycles misinterpreted as capture losses
Solution Approach 1:
The vectorogram analysis provides an additional spatial dimension that enables continuous monitoring while filtering out atypical cycles. The geometric properties of the vectorogram (area, orientation, shape) serve as robust features that maintain high specificity even when analyzing every cycle, allowing the system to achieve both fast reactivity and high reliability simultaneously.
Solution Approach 2:
The system implements continuous feedback through cycle-by-cycle vectorogram analysis, comparing each cycle's geometric features against established patterns. This feedback mechanism enables rapid detection of true capture losses while the multidimensional analysis provides discriminative power to reject false positives from atypical cycles, resolving the contradiction between speed and reliability.
3Reliability
If multiple capture tests are run for each site in multi-site devices, then complete coverage of all stimulation sites is achieved, but the test duration increases substantially
Solution Approach 1:
The patent merges the analysis of multiple stimulation sites into a unified vectorogram framework. By representing each site's response in the same 2D vectorogram space and comparing geometric features, the system can evaluate multiple sites simultaneously or in rapid succession, maintaining complete testing coverage while dramatically reducing overall test duration through efficient multidimensional comparison.
Data Source
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AI summary
The device has a delivering unit delivering electrical stimulation pulses of low energy to an electrode implanted in a heart chamber of a patient. A collecting unit collects electrical activity of the chamber, and comprises a producing unit for producing two distinct temporal components from two distinct electrogram intracardiac electrogram (EGM) signals of the chamber. An analysis unit performs a bi-dimensional analysis, delivers a descriptor parameter of two-dimensional non-temporal characteristic, and determines a presence or a loss of a capture based on the parameter.