Arcuate Stent with Biodegradable Inner Layer for Anastomosis
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
End-to-end anastomoses in vascular surgeries often result in stenosis due to intimal hyperplasia, leading to vessel occlusion, which is challenging to prevent with existing stent technologies, especially at complex side-to-side junctures.
Innovation Solution
An elongate, arcuate external stent with a rigid outer layer and a biodegradable inner layer that stimulates neovascularization, allowing unrestricted expansion and potential delivery of active agents, designed for use in various anastomosis types, including end-to-side and side-to-side configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a rigid stent structure is used to maintain vessel patency, then mechanical support is improved, but vessel expansion and neovascularization are restricted
Solution Approach 1:
The stent is divided into an outer layer and an inner layer with distinct functions. The outer layer provides rigid mechanical support to maintain vessel patency, while the inner layer is biodegradable and allows vessel expansion and neovascularization. This segmentation resolves the contradiction by separating the structural support function from the adaptability function.
Solution Approach 2:
The stent structure transitions from a single rigid material to a composite of rigid outer layer and biodegradable inner layer. The inner layer degrades over time, dynamically changing the stent's parameters from rigid to progressively more compliant, allowing vessel expansion while maintaining initial mechanical support.
2Reliability
If a biodegradable inner layer is used to stimulate neovascularization, then biological integration is improved, but structural support deteriorates over time
Solution Approach 1:
The biodegradable inner layer is pre-installed to stimulate neovascularization and biological integration during the critical early healing phase. By this time, the vessel wall has begun to strengthen, so the structural support requirement is reduced, allowing the inner layer to degrade safely.
Solution Approach 2:
The stent structure is designed to be dynamic rather than static. The inner layer progressively degrades over time, transferring the structural load from the stent to the healing vessel wall. This dynamic adaptation resolves the contradiction between providing initial support and allowing long-term biological integration.
3Reliability
If the inner layer degrades faster than the outer layer, then neovascularization is promoted, but manufacturing precision becomes more challenging
Solution Approach 1:
The stent uses composite materials with different degradation rates - a biodegradable inner layer (e.g., collagen, polylactic acid) that degrades faster than the non-biodegradable or slowly degradable outer layer (e.g., stainless steel, shape memory alloy). This composite structure inherently provides the required degradation rate differential through material selection rather than complex manufacturing controls.
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 stent effectively reduces stenosis risk by promoting neovascularization and allowing vessel expansion, maintaining patency and reducing re-stenosis at complex anastomotic sites, thereby improving the success rate of vascular grafting procedures.
Implementation Method 1
the inner layer is of a material that stimulates neovascularisation, wherein said material is biodegradable and degrades faster than the outer layer
Implementation Method 2
the materials of the inner and outer layers are maintained in contact by their natural elasticity
Data Source
Figure 1~2
AI summary
An elongate device (19), arcuate in cross-section, for placement around a vessel (4), comprises an essentially non-porous outer layer and a biodegradable inner layer. An alternative device comprises a tubular portion (3) for placement around a graft and a portion (2), arcuate in cross-section that can straddle a native vessel, at the site of an end- to-side anastomosis.