MRI-Compatible Implantable Lead Dummy Contact Design
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Solution Overview
Problem
Implantable electrical stimulation systems face compatibility issues with magnetic resonance imaging (MRI) due to radio frequency (RF) pulses, which can cause tissue damage, unintended stimulation, or device malfunction.
Innovation Solution
The design of an implantable lead with a lead body featuring electrodes and dummy contacts, where the dummy contacts are positioned proximal to the electrodes and are configured to block low-frequency signals, reducing the absorption and transmission of MRI-induced currents and voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional implantable leads are used during MRI procedures, then the lead can perform its therapeutic function, but the lead absorbs RF energy causing tissue heating and potential damage
Solution Approach 1:
The patent introduces an intermediary component - the dummy contact - that acts as a mediator between the RF field and the functional electrodes. The dummy contact intercepts RF energy and provides an alternative current path through the lead body to ground, preventing direct RF-induced current flow through the functional electrodes and reducing tissue heating while maintaining therapeutic function
Solution Approach 2:
The patent converts the harmful RF energy absorption into a beneficial effect by directing the RF-induced currents through the dummy contact and lead body to ground. This alternative current path dissipates RF energy safely through the lead structure rather than through the functional electrodes and tissue, transforming the potential harm into a protective mechanism
2Object-affected harmful factors
If the lead structure is modified to reduce MRI heating, then patient safety during MRI improves, but the lead design becomes more complex
Solution Approach 1:
The patent segments the lead contacts into functional electrodes and dummy contacts. This segmentation allows the dummy contacts to specifically handle RF energy dissipation while the functional electrodes maintain their therapeutic function, dividing the lead's role into distinct components that address different requirements without significantly increasing overall complexity
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 use of dummy contacts in the implantable lead effectively reduces MRI-induced RF lead heating and currents, thereby enhancing patient safety and device functionality during MRI procedures.
Implementation Method 1
The lead further includes a high pass filter or a switch in the lead body configured to block low frequency signals passing through the at least one conductive dummy wire
Implementation Method 2
at least one conductive wire electrically coupling the at least one electrode to the at least one therapy terminal contact
Data Source
AI summary
An implantable lead including a lead body, an electrode disposed along the distal end of the lead body, and a dummy contact disposed along the lead body. A terminal electrode contact is disposed along the proximal end of the lead body and is coupled to the electrode via a conductive wire, and a conductive dummy wire is couple to the dummy contact but is free of connection to any terminal electrode contact. The conductive dummy wire may connect to a dummy terminal adapted to be coupled to a pulse generator housing via a high pass filter or a switch.