Shielded RF Chokes in Implantable Electrical Leads for MRI Safety
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Solution Overview
Problem
Current electrical leads for implantable devices, such as pacemakers and neurostimulators, are prone to excessive heating during MRI scans due to electromagnetic field induction, posing safety risks and limiting the use of MRI for patients with metallic implants.
Innovation Solution
The design incorporates pairs of adjacent segments of electrical wire with shielded RF chokes, including inductors covered by conductive shielding material and a core, to resist the induction of currents from external electromagnetic fields, thereby reducing heating during MRI procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrical leads are used in implantable devices, then the device can perform its intended function, but excessive heating occurs during MRI scans due to electromagnetic field induction
Solution Approach 1:
The patent introduces an intermediary substance (e.g., ferrite beads, magnetic particles, or specialized shielding materials) between the electrical lead and the external electromagnetic field during MRI scans. This intermediary absorbs or redirects the electromagnetic energy, preventing it from being converted into excessive heat in the lead, thereby resolving the contradiction between maintaining lead functionality and preventing overheating
Solution Approach 2:
The patent modifies the physical or chemical parameters of the lead or its surrounding environment to reduce electromagnetic induction. This may include changing the lead's electrical resistance, introducing magnetic shielding materials with specific permeability, or adjusting the lead's geometric configuration to minimize induced currents, thereby reducing temperature increase during MRI while maintaining operational reliability
2Reliability
If electrical leads are made more resistant to electromagnetic induction, then heating during MRI is reduced, but the device complexity increases
Solution Approach 1:
The patent divides the electrical lead into multiple segments or sections, with specific portions (such as ferrite beads, shielding segments, or insulated sections) strategically placed to provide electromagnetic protection. This segmentation allows the lead to maintain overall simplicity while incorporating targeted complexity only where needed to resist induction, balancing reliability improvement with device complexity management
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 solution effectively minimizes the induction of currents and subsequent heating, allowing for safer MRI scans on patients with implantable devices by trapping electromagnetic fields and preventing interaction with external fields, thus ensuring reduced temperature increases and enhanced safety.
Implementation Method 1
The design incorporates pairs of adjacent segments of electrical wire with shielded RF chokes, including inductors covered by conductive shielding material and a core, to resist the induction of currents from external electromagnetic fields
Implementation Method 2
The design incorporates pairs of adjacent segments of electrical wire with shielded RF chokes, including inductors covered by conductive shielding material and a core, to resist the induction of currents from external electromagnetic fields, thereby reducing heating during MRI procedures
Data Source
Figure 1~3
Figure 4~6A
Figure 6B
AI summary
A lead for an electronic device which resists the induction of a current from an electromagnetic field external to said lead includes one or more pairs of adjacent segments of electrical wire, each of the pairs including a first segment of electrical wire and a second segment of electrical wire. The lead also includes one or more shielded RF chokes, wherein each of the shielded RF chokes is provided between the first segment of electrical wire and the second segment of electrical wire of a respective one of the one or more pairs of adjacent segments. Also, an implantable device that includes a generator for generating one or more electrical pulse and a lead as described for delivering the pulses to tissue within a patient's body. A method for making the described implantable device is also provided.