Multi-element Contact Assemblies for MRI-Compatible Implantable Leads
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Solution Overview
Problem
Conventional implantable electrical stimulation systems are incompatible with magnetic resonance imaging (MRI) due to the adverse effects of radiofrequency (RF) pulses, which can cause tissue damage and premature failure of electronic components.
Innovation Solution
The implementation of multi-element contact assemblies in implantable leads, where conductors are arranged in a series of units with overlapping segments to form multi-coil regions, reducing the impact of RF irradiation and enhancing the stability of electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional implantable electrical stimulation systems are used, then the systems can provide therapeutic stimulation, but they are incompatible with MRI due to RF pulses causing tissue damage and component failure
Solution Approach 1:
The contact assembly is divided into multiple conductive elements (inner contact, outer contact, and intermediate contacts) arranged in a multi-element configuration. This segmentation allows each element to be individually optimized for RF current management while maintaining electrical connectivity, thereby reducing overall RF-induced heating and improving MRI compatibility
Solution Approach 2:
The contact assembly features a nested structure where the inner conductive contact is positioned within the outer conductive contact, with intermediate contacts nested between them. This nested arrangement creates multiple concentric conductive paths that distribute RF currents and reduce localized heating, enabling safe operation during MRI procedures
2Reliability
If multi-element contact assemblies are implemented, then MRI compatibility is improved by reducing RF pulse effects, but the device complexity increases
Solution Approach 1:
The multi-element contact assembly serves multiple functions simultaneously: it provides electrical connectivity for stimulation therapy, distributes RF currents during MRI to reduce heating, and maintains a compact form factor. This multi-functionality allows the increased structural complexity to be justified by the dual benefits of therapeutic performance and MRI 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
This configuration minimizes the adverse effects of RF pulses during MRI, ensuring the safety and efficacy of the electrical stimulation system by reducing tissue heating and preventing premature component failure.
Implementation Method 1
The RF pulses can generate transient signals in the conductors and electrodes of an implanted lead. These signals can have deleterious effects including, for example, unwanted heating of the tissue causing tissue damage
Data Source
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Figure 3A~4
AI summary
An implantable lead includes a lead body having a plurality of electrodes disposed on a distal end of the lead body, a plurality of terminals disposed on a proximal end of the lead body, and a plurality of conductors disposed along the lead body such that each conductor electrically couples at least one of the electrodes to at least one of the terminals. At least one of the electrodes or terminals includes a multi¬ element contact assembly. The multi-element contact assembly includes at least one conductive inner element and at least one conductive outer element disposed over the inner element. At least one of the plurality of conductors is electrically coupled to one of the multi-element contact assemblies such that the conductor is positioned against the at least one inner element. The at least one outer element includes a region that is in contact with the at least one inner element.