Implantable Medical Device Insulation Breach Detection
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Solution Overview
Problem
Implantable medical devices (IMDs) face challenges in detecting short circuit conditions in medical electrical leads, which can occur intermittently and may not be detected by scheduled impedance measurements, potentially leading to inadequate therapy delivery during life-threatening conditions like ventricular fibrillation.
Innovation Solution
An IMD system with a controller that analyzes cardiac electrical signals, specifically using electrograms, to detect short circuit events by determining the slope of the signal and comparing it to a short circuit threshold, allowing for real-time monitoring and detection of potential short circuits in medical electrical leads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If scheduled impedance measurements are used to detect lead short circuits, then the device structure remains simple, but detection reliability is insufficient for intermittent short circuit conditions
Solution Approach 1:
The system performs preliminary analysis of cardiac electrogram signals to establish baseline characteristics and detect deviations indicating short circuit conditions before they compromise therapy delivery. The controller continuously monitors electrogram morphology, amplitude, and timing parameters to identify insulation breaches proactively.
Solution Approach 2:
The patent replaces traditional electrical impedance measurement methods with electrogram signal analysis. By substituting the measurement principle from impedance-based detection to electrogram-based detection, the system achieves superior sensitivity for intermittent short circuits while utilizing existing sensing circuitry already present in the IMD.
2Loss of time
If continuous real-time monitoring of cardiac signals is implemented to detect short circuits, then detection speed improves, but energy consumption increases
Solution Approach 1:
The system applies partial monitoring by focusing computational resources on analyzing specific electrogram parameters most indicative of short circuit conditions, such as signal amplitude thresholds and morphology changes, rather than performing exhaustive continuous analysis of all signal characteristics.
Solution Approach 2:
The controller performs short circuit detection analysis at periodic intervals based on detected arrhythmia events or signal quality metrics, rather than continuously analyzing every electrogram sample. This periodic assessment approach maintains detection capability while reducing overall computational energy expenditure during normal operation.
3Reliability
If traditional impedance measurement methods are used, then the detection method is simple, but it fails to detect intermittent short circuit conditions
Solution Approach 1:
The system incorporates feedback mechanisms where detected electrogram abnormalities trigger additional verification measurements and analysis. When a potential short circuit is identified through electrogram analysis, the controller adjusts monitoring parameters and performs confirmatory assessments to reduce false positives while maintaining high detection sensitivity.
Solution Approach 2:
The patent utilizes changes in electrogram signal parameters such as amplitude, duration, and morphology to detect short circuit conditions. By monitoring multiple electrical signal characteristics simultaneously and comparing them against established thresholds, the system achieves robust detection of intermittent insulation breaches that single-parameter impedance methods miss.
Data Source
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AI summary
An implantable medical device capable of sensing cardiac signals and delivering cardiac electrical stimulation therapies is enabled to detect a short circuit event. A signal is sensed by a sensing module coupled to electrodes. A controller detects a short circuit event in response to a slope of the sensed signal exceeding a short circuit threshold.