Shape Memory Alloy Valve Frame for Vein Patency
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Solution Overview
Problem
Existing prosthetic valves for treating venous valve insufficiency face challenges in conforming to the dynamic shape of veins due to varying blood flow velocities, pressures, and volumes, requiring a balance between radial strength and flexibility to prevent collapse or irritation, while also ensuring patency and minimizing migration and irritation within the body vessel.
Innovation Solution
A support frame with a proximal and distal annular member connected by longitudinal members, formed from biocompatible materials like shape memory metal, providing radial strength and flexibility to maintain vein patency while minimizing irritation, and a prosthetic valve with moveable leaflets to regulate fluid flow, deployed using a catheter system for percutaneous implantation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the implantable frame has high radial strength to maintain vein patency, then the vein remains open, but the frame lacks flexibility and may damage the vein by failing to compress in response to normal fluctuations in the vein diameter
Solution Approach 1:
The frame transitions from a static rigid structure to a dynamic structure that can adapt its mechanical properties. The shape memory alloy allows the frame to be compressed during delivery and then self-expand to a predetermined shape at the implantation site, providing radial strength when needed while maintaining the ability to respond to physiological movements and fluctuations in vein diameter
Solution Approach 2:
The mechanical parameters of the frame (radial strength, flexibility, stiffness) are changed by utilizing the phase transformation properties of shape memory alloy. The material can transition between austenite (high strength) and martensite (low strength, high flexibility) phases, allowing the frame to provide radial support when needed while remaining flexible during delivery and physiological movement
2Reliability
If the implantable frame has high surface area contacting the interior wall of the vein to provide durability, then the frame is more durable, but it may induce inflammation or trauma in the vein wall
Solution Approach 1:
The frame structure is designed with non-contacting longitudinal members that provide structural support and durability without requiring continuous contact with the vein wall. The radial strength is provided through the self-expanding geometry and material properties rather than through friction or contact pressure, thereby reducing inflammation and trauma while maintaining durability
Solution Approach 2:
The frame is divided into multiple longitudinal members spaced apart from each other, creating a segmented structure. This segmentation provides sufficient radial support and durability while minimizing the continuous surface area in contact with the vein wall, reducing the risk of inflammation and trauma
3Stability of the object's composition
If the frame is rigid enough to maintain vein patency under repeated fluctuations, then patency is maintained, but the frame may collapse or fracture if lacking sufficient radial strength
Solution Approach 1:
The frame utilizes shape memory alloy, a composite material system combining nickel and titanium with specific compositional ratios. This composite material provides both the radial strength needed to maintain patency under pressure fluctuations and the flexibility to respond to physiological movements without collapsing or fracturing
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 support frame effectively distributes stress and strain forces, maintains vein patency, and minimizes irritation, while the prosthetic valve efficiently regulates blood flow, addressing the challenges of dynamic vein changes and ensuring long-term functionality.
Implementation Method 1
formed from biocompatible materials like shape memory metal, providing radial strength and flexibility to maintain vein patency
Data Source
AI summary
The disclosure relates to support frames for prosthetic implantable valves. The support frames may include a plurality of symmetrically arrayed interconnected U-shaped member structures. Preferred support frames are tubular structures enclosing a longitudinal axis and including a plurality of U-shaped member structures facing a distal or a proximal end of the support frame. Each U-shaped member structure may be connected to a single longitudinally adjacent U-shaped member facing in an opposite longitudinal direction, as well as two laterally adjacent U-shaped members.