MRI Implantable Lead Conductor Inductance Design
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Solution Overview
Problem
Implantable medical devices, such as pacemakers and ICDs, face compatibility issues with magnetic resonance imaging (MRI) due to the induction of RF currents, leading to potential heat buildup and adverse cardiac stimulation during MRI procedures.
Innovation Solution
The design of implantable medical device leads with specific conductor configurations, including inner and outer coils with tailored inductance values and pitches, to minimize RF current induction and heat generation, ensuring MRI compatibility while maintaining therapeutic effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional conductor configurations are used in implantable leads, then the leads can effectively deliver pacing therapy and electrical shocks, but they experience significant RF current induction and heat buildup during MRI procedures
Solution Approach 1:
The patent changes the inductance parameter of the conductor coils to specific ranges (inner coil: 0.2-0.5 μH/inch, outer coil: 0.1-0.3 μH/inch) to reduce RF current induction during MRI while maintaining therapeutic effectiveness. This parameter optimization resolves the contradiction by tuning the electrical characteristics to be MRI-compatible.
Solution Approach 2:
The patent employs composite conductor structures combining multiple filars wound in specific configurations (unifilar inner coil with multi-filar outer coil) to achieve the desired inductance characteristics. This composite construction allows simultaneous optimization of therapeutic performance and MRI safety.
2Object-affected harmful factors
If conductor inductance is increased to reduce RF current induction, then MRI compatibility improves, but the conductor design complexity increases
Solution Approach 1:
The patent segments the conductor into distinct inner and outer coils with specific inductance requirements. The inner coil (0.2-0.5 μH/inch) and outer coil (0.1-0.3 μH/inch) are designed as separate functional elements, each optimized for its specific role in reducing RF current induction while managing overall design complexity through modular architecture.
3Object-affected harmful factors
If multi-filar outer coils are used to achieve desired inductance values, then MRI compatibility is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent specifies precise inductance parameters (inner coil: 0.2-0.5 μH/inch, outer coil: 0.1-0.3 μH/inch) that can be achieved through controlled manufacturing processes. By defining clear parameter ranges rather than single values, the patent balances manufacturing precision requirements with MRI compatibility benefits, allowing for tolerable manufacturing variations while maintaining safety.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The proposed lead designs effectively reduce temperature increases and minimize adverse cardiac effects during MRI procedures, ensuring both safety and efficacy of the medical devices.
Implementation Method 1
the induction of RF currents, leading to potential heat buildup and adverse cardiac stimulation during MRI procedures
Implementation Method 2
potential heat buildup and adverse cardiac stimulation during MRI procedures
Data Source
AI summary
An implantable medical device lead includes an inner conductor coil comprising one or more generally cylindrically wound filars. The inner conductor coil is configured to have a first inductance value greater than or equal to 0.2 μH/inch when the inner conductor coil is subjected to a range of radio frequencies. The implantable medical device lead also includes a multi-filar outer coil comprising two or more generally cylindrically wound filars. The multi-filar outer coil is configured to have a second inductance value greater than or equal to 0.1 μH/inch when the multi-filar outer coil is subjected to the range of radio frequencies.