Implantable Medical System Lead Fault Tolerance
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Solution Overview
Problem
Implantable medical devices face challenges in sustaining therapy delivery due to lead-related conditions such as conductor breaches or fractures, which can cause short or open circuits, impairing sensing and therapy effectiveness.
Innovation Solution
An implantable medical system with alternate therapy vectors, including a lead with a first and alternate electrode, and an oversense reduction module that reconfigures therapy delivery and sensing functions to maintain therapy in case of lead-related conditions by switching to unaffected electrode-conductor sets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lead conductors are used for therapy delivery and sensing, then therapy function is provided, but lead-related conditions (breaches, fractures) can cause short or open circuits impairing therapy effectiveness
Solution Approach 1:
The system performs preliminary detection of lead-related conditions by monitoring impedance and therapy effectiveness before complete failure occurs. The detector identifies conductor breaches or fractures early, allowing the system to switch to alternate electrodes before therapy is completely compromised.
Solution Approach 2:
The system provisions alternate electrodes as a backup before the primary lead conductors fail. These alternate electrodes are ready to immediately assume therapy delivery and sensing functions if lead-related conditions develop, cushioning against complete therapy failure.
2Duration of action of stationary object
If the system switches to alternate electrodes in response to lead-related conditions, then therapy continuity is maintained, but system complexity increases
Solution Approach 1:
The implantable medical device is designed with multi-functionality, incorporating both primary lead conductors and alternate electrodes that can perform therapy delivery and sensing. The same device housing and control circuitry support multiple electrode configurations, allowing seamless switching without requiring separate backup systems.
Solution Approach 2:
The detector and control circuitry serve as intermediaries between the primary lead conductors and alternate electrodes. These components monitor the status of primary conductors and automatically mediate the transition to alternate electrodes when lead-related conditions are detected, simplifying the switching process.
3Reliability
If multiple electrode-conductor sets are provided for alternate therapy vectors, then fault tolerance is improved, but lead body complexity and potential failure points increase
Solution Approach 1:
The system merges the primary lead conductors and alternate electrodes into a single integrated lead body structure. Multiple electrode-conductor sets are combined within one lead, sharing common insulation and structural support, which reduces overall lead body complexity compared to having separate redundant leads.
Solution Approach 2:
The lead body is segmented into multiple functional sections, each containing electrode-conductor sets that can operate independently. This segmentation allows the lead to provide multiple therapy vectors while maintaining modular organization, making the complex structure more manageable and potentially easier to manufacture.
Data Source
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AI summary
The disclosure describes implantable medical systems that respond to occurrence of a lead-related condition by utilizing an elongated coil electrode in defining an alternative pacing therapy vector to maintain optimal drain of an IMD power supply. An exemplary system includes a medical electrical lead having an elongated electrode and an improved sensing and therapy delivery circuitry to provide the alternative pacing therapy vector responsive to the lead-related conditions. The system reconfigures the operation of the sensing and therapy delivery circuitry triggered by the switch to the alternative pacing therapy vector.