Bio-erodible Polymer Scaffolds for Peripheral Vessels
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Solution Overview
Problem
Polymeric scaffolds for peripheral vessels face challenges in maintaining structural integrity and preventing late lumen loss and stenosis due to unpredictable mechanical properties and complex loading conditions, which are not adequately addressed by existing methods.
Innovation Solution
A balloon-expandable, bio-erodible polymer scaffold with a network of rings interconnected by at most two links, featuring a high number of crests and troughs, designed to enhance surface area support and reduce fracture rates, thereby improving vascular patency and minimizing late lumen loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the scaffold uses a traditional design with fewer crests and troughs, then the radial strength is higher, but the surface area support is reduced and fracture rate increases
Solution Approach 1:
The scaffold is divided into multiple crests and troughs (at least 6 of each) around the circumferential direction, segmenting the support structure into finer units. This segmentation increases the total surface area in contact with the vessel wall while distributing mechanical loads across multiple segments, thereby maintaining radial strength despite the increased complexity
Solution Approach 2:
The invention adds dimensional complexity by creating a three-dimensional arrangement of crests and troughs that extend circumferentially around the scaffold. This multi-dimensional structure increases the effective surface area for vessel support without compromising the radial strength, as the load is distributed across multiple elevated crests rather than concentrated in a single plane
2Stability of the object's composition
If the scaffold uses a design with more links connecting rings, then the structural stability is improved, but the fracture rate increases under cyclic loading
Solution Approach 1:
The invention extracts or removes excess links connecting adjacent rings, limiting the connection to at most two links per ring pair. This reduction eliminates redundant structural elements that create stress concentration points under cyclic loading, thereby reducing the fracture rate while maintaining sufficient structural stability through the optimized crest and trough configuration
Solution Approach 2:
The invention changes the structural parameters by reducing the number of links between rings from traditional multi-link designs to at most two links. This parameter change decreases the complexity of the joint structure, reducing stress concentrations and improving reliability under cyclic axial and bending loads while maintaining structural integrity through the optimized ring configuration
3Duration of action of stationary object
If the scaffold remains in the body for long-term support, then the vascular patency is maintained, but the risk of late lumen loss and stenosis increases
Solution Approach 1:
The invention changes the material parameter from permanent to bio-erodible polymer composition, allowing the scaffold to maintain structural integrity and provide vascular support for the required duration (up to 3 months or more) and then gradually degrade. This parameter change enables the scaffold to fulfill its long-term support function while eliminating the persistent harmful effects of permanent foreign body presence, reducing late lumen loss and stenosis risk
Data Source
AI summary
A medical device includes a polymer scaffold crimped to a catheter having an expansion balloon. The scaffold has a structure that produces a low late lumen loss when implanted within a peripheral vessel and also exhibits a high axial fatigue life. In a preferred embodiment the scaffold forms ring structures interconnected by links, where a ring has 12 crowns and at most two links connecting adjacent rings.