Implantable Device RF Heating Reduction via Coupled Conductors
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Solution Overview
Problem
Implantable medical devices, such as electrode leads for electrostimulation, experience unwanted heating due to electrical currents induced by external alternating magnetic fields, particularly in MRI machines, which limits their use in patients with pacemakers or defibrillators.
Innovation Solution
A medical device with a longitudinally extended first electrical conductor and a second electrical conductor coupled within a shared insulating sheathing, allowing for electromagnetic radiofrequency wave coupling to redirect induced currents away from the functional lead, thereby reducing heating through inductive, capacitive, or ohmic coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a functional electrical conductor is used for delivering therapeutic signals or detecting diagnostic signals, then the device can perform its intended medical functions, but the conductor heats up due to electrical currents induced by external alternating magnetic fields in MRI machines
Solution Approach 1:
The patent introduces a second electrical conductor as an intermediary element that couples to the functional conductor. This second conductor acts as a mediator to redirect induced currents away from the functional conductor, reducing heating while preserving the functional conductor's ability to deliver therapeutic signals or detect diagnostic signals.
Solution Approach 2:
The patent converts the harmful effect of induced currents into a beneficial outcome by using the second conductor to deliberately redirect these currents. The induced currents that would normally heat the functional conductor are instead channeled through the second conductor, transforming a harmful thermal effect into a controlled current path that protects the functional element.
2Object-affected harmful factors
If the functional lead is protected from induced currents, then heating is reduced, but the device structure becomes more complex with additional conductors and coupling mechanisms
Solution Approach 1:
The patent merges the protective function with the existing lead structure by integrating the second conductor into the same insulating sheathing as the functional conductor. This combining of elements achieves heating reduction without requiring entirely separate protective structures, thereby limiting the increase in device complexity.
Solution Approach 2:
The patent uses a shared insulating sheathing that encloses both conductors, providing a unified protective structure. This approach simplifies the overall design compared to using separate protective layers for each conductor, as the insulating sheathing serves both mechanical protection and electrical isolation functions simultaneously.
3Object-affected harmful factors
If electromagnetic coupling is used to redirect induced currents, then heating of the functional lead is reduced, but energy is transferred to other tissue areas which may experience heating
Solution Approach 1:
The patent extracts the harmful heating effect from the functional lead by redirecting induced currents through the second conductor. The second conductor serves as a dedicated pathway that removes the thermal burden from the functional conductor, isolating the heating effect to a non-functional element that can be designed to minimize tissue impact.
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 reduces unwanted heating of the functional leads and electrode poles, minimizing tissue heating and allowing for safer MRI examinations by redistributing induced current heating to other tissue areas.
Implementation Method 1
coupling between the first and the second electrical conductors, which are designed to input electromagnetic radiofrequency waves guided in the first conductor at least partially into the second electrical conductor
Implementation Method 2
guided in a shared insulating sheathing
Data Source
AI summary
Temporarily or permanently implantable medical device, having at least one longitudinally extended first electrical conductor having a functional lead, which is connected to a functional electrode pole for dispensing therapeutic signals or for detecting diagnostic signals, and including at least one second electrical conductor, which is coupled to the functional lead and is guided with it in a shared insulating sheathing, such that a coupling between the functional lead and the second electrical conductor is designed to input electromagnetic radiofrequency waves guided in the functional lead at least partially into the second electrical conductor.