IMD Lead Reactance Configuration for MRI Energy Reflection
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Solution Overview
Problem
Implantable medical devices (IMDs) face challenges when exposed to disruptive energy fields, such as those from MRI scans, as they can induce energy leading to lead heating, RF rectification, and device heating, affecting the device's operation and patient safety.
Innovation Solution
The configuration of parasitic inductances and reactances in IMD components to reflect electromagnetic energy away from the lead, reducing the amount of energy reflected and absorbed, thereby minimizing heating effects and maintaining device functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the IMD is exposed to a disruptive energy field (e.g., MRI scan), then diagnostic or therapeutic procedures can be performed on the patient, but lead heating, RF rectification, and device heating effects occur that alter IMD operation
Solution Approach 1:
The patent applies preliminary anti-action by configuring reactive components (capacitors and inductors) within the IMD to create an electrical network that proactively counteracts the harmful effects of disruptive energy fields. The network is designed to reflect electromagnetic energy away from the lead before it can cause significant heating, rather than attempting to mitigate heating after it occurs. This preemptive approach allows the device to maintain its operational integrity while undergoing necessary medical procedures like MRI scans.
2Ease of manufacture
If conventional IMD design is used, then the device can be manufactured with standard components, but parasitic inductances and capacitances cause electromagnetic energy to be reflected along the lead, increasing heating effects
Solution Approach 1:
The patent converts the harmful parasitic inductances and capacitances inherent in standard IMD components into a beneficial feature. By deliberately configuring these reactive elements to form an electrical network with specific impedance characteristics, the design transforms what would normally be sources of reflected electromagnetic energy and heating into components that actively reduce such reflections. This approach maintains ease of manufacture with standard components while eliminating the associated harmful effects.
3Reliability
If the IMD reflects electromagnetic energy to protect internal components, then device heating is reduced, but more energy is reflected along the lead toward the electrodes, increasing lead heating
Solution Approach 1:
The patent introduces an intermediary electrical network consisting of strategically placed reactive components that act as a mediator between the disruptive energy field and the IMD's internal components. This network is configured to reflect electromagnetic energy in a controlled manner that protects sensitive internal circuitry while minimizing the reflection of energy along the lead toward the electrodes. The intermediary network thus resolves the contradiction by selectively managing where reflected energy is directed.
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 approach effectively reduces lead heating and device heating caused by disruptive energy fields, ensuring the IMD's stability and safety during exposure to MRI and other electromagnetic sources.
Implementation Method 1
The energy from the electromagnetic energy source may induce current flow within electrical components of the lead, which can produce lead heating, RF rectification, and device heating effects
Implementation Method 2
The energy from the electromagnetic energy source may induce current flow within electrical components of the lead, which can produce lead heating, RF rectification, and device heating effects
Implementation Method 3
The parasitic inductances and/or capacitances of such components may be utilized to deliberately design an electrical network that reduces the amount of electromagnetic energy reflected along a lead by the IMD for a given frequency or range of frequencies
Data Source
AI summary
Techniques are described for controlling effects caused when an implantable medical device (IMD) is subject to a disruptive energy field. The IMD may include an implantable lead that includes one or more electrodes. The IMD may further include a first component having a parasitic inductance. The IMD may further include a second component having a reactance. In some examples, the reactance of the second component may be selected based on the parasitic inductance of the first component such that an amount of energy reflected along the lead in response to energy produced by an electromagnetic energy source is below a selected threshold. In additional examples, the parasitic inductance of the first component and the reactance of the second component are configured such that an amount of energy reflected along the lead in response to a frequency of electromagnetic energy is below a selected threshold.