Shape Memory Polymer Lead Fixation for Sacral Nerve Stimulation
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Solution Overview
Problem
Existing implantable neurostimulation leads face challenges in maintaining electrode contact with sacral nerves due to movement and migration, which complicates the treatment of pelvic floor disorders like urinary incontinence, as current fixation mechanisms are difficult to reposition and may cause harmful lead displacement.
Innovation Solution
An implantable medical electrical lead featuring a shape memory polymer portion that changes configuration upon exposure to a transition stimulus, providing increased resistance to movement within the body tissue and facilitating easier repositioning and fixation, thereby stabilizing the lead and maintaining effective electrode contact with sacral nerves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a fixation mechanism is used to prevent lead migration, then lead stability is improved, but the ability to reposition the lead is worsened
Solution Approach 1:
The fixation mechanism transitions from a static fixed state to a dynamic adjustable state. The lead fixation mechanism can be activated or deactivated to allow movement, providing both stability during operation and ease of repositioning when needed, resolving the contradiction between fixed stability and repositioning flexibility
Solution Approach 2:
The fixation mechanism changes its mechanical properties (rigid to flexible) in response to environmental conditions. The polymer's glass transition temperature change alters its rigidity, allowing it to be flexible during implantation for easy positioning, then rigid after implantation for stable fixation, thus resolving the contradiction between repositioning ease and lead stability
2Reliability
If the lead is firmly fixed to prevent migration, then electrode contact stability is improved, but the ease of placement is worsened
Solution Approach 1:
The polymer's physical state changes with temperature. During implantation at body temperature, the polymer is in a flexible rubbery state above its glass transition temperature, enabling easy placement and positioning. After implantation, cooling below the glass transition temperature transforms it to a rigid glassy state, ensuring reliable electrode contact stability and preventing migration
Solution Approach 2:
The lead is implanted in a flexible state first, allowing easy placement and positioning before the fixation mechanism is activated. The polymer is then cooled to transform it to a rigid state, providing stable fixation. This preliminary action sequence resolves the contradiction between ease of placement and electrode contact stability
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 shape memory polymer lead enhances the stability and efficacy of neurostimulation by resisting movement and migration, allowing for more reliable treatment of pelvic floor disorders without the need for surgical sutures, and enabling easier placement and adjustment during implantation.
Implementation Method 1
at least one shape memory polymer portion that has a first configuration and a second configuration, wherein the second configuration is obtained upon exposure of the shape memory polymer portion to a transition stimulus
Data Source
AI summary
An implantable medical electrical lead for electrical stimulation of body tissue that includes at least one shape memory polymer portion that has a first configuration and a second configuration, wherein the second configuration is obtained upon exposure of the shape memory polymer portion to a transition stimulus, and wherein the second configuration of the modifiable portion exhibits a greater resistance to movement of the lead within the body tissue than does the first configuration; and at least one electrode configured to provide electrical stimulation of body tissue, wherein the lead has a proximal end and a distal end. Systems and kits as well as methods of utilizing the leads of the invention are also included.