Low-Profile Stent Graft With Low Modulus Suture
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Solution Overview
Problem
Current stent grafts with thin grafts face issues of needle hole formation and enlargement at suture sites, leading to type III endoleak, which is exacerbated by high blood pressure over time, and existing solutions either increase graft thickness or fail to prevent needle hole enlargement effectively.
Innovation Solution
A stent graft design featuring a tubular graft with a thickness of 10 μm to 90 μm, joined with a suture thread having a modulus of elasticity of 40 cN/dtex or less, made from materials like polyester or polyamide, and a braid form with specific braiding angles and densities to minimize needle hole formation and enlargement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the wall thickness of the graft is reduced to achieve low profile stent graft devices, then the catheter outer diameter is reduced and applicability to patients with narrower arteries is improved, but needle holes are easily opened and enlarged at suture sites leading to type III endoleak
Solution Approach 1:
The invention changes the physical-chemical parameters of the suture thread by specifying a modulus of elasticity of 40 cN/dtex or less, which is significantly lower than conventional suture threads. This parameter change allows the suture thread to be more flexible and less likely to open needle holes in thin grafts, while still maintaining adequate tensile strength for securing the stent graft.
Solution Approach 2:
The invention applies local quality by making the suture thread have different properties than the graft material itself. The suture thread is specifically designed with low modulus of elasticity (40 cN/dtex or less) to be gentler on the thin graft tissue at suture sites, while the graft itself maintains its thin wall structure (10-90 μm) for low profile requirements.
2Ease of manufacture
If conventional suture threads with high modulus of elasticity are used to secure thin grafts, then the stent graft can be assembled, but needle holes are easily opened and enlarged under blood pressure over time
Solution Approach 1:
The invention changes the modulus of elasticity parameter of the suture thread to 40 cN/dtex or less, which balances the competing requirements of ease of manufacture (adequate tensile strength) and long-term durability (gentle on thin graft tissue under cyclic blood pressure loading).
Solution Approach 2:
The low modulus of elasticity of the suture thread acts as a cushioning mechanism that absorbs and distributes the mechanical stress from blood pressure before it can damage the thin graft tissue at needle holes, preventing progressive enlargement over time.
3Reliability
If grommets are attached to graft suture sites to fill needle holes, then type III endoleak is prevented, but the wall thickness of the graft is increased and the stent graft cannot be folded small
Solution Approach 1:
The invention changes the fundamental approach from adding thickness (grommets) to changing the suture thread parameter (modulus of elasticity). By making the suture thread sufficiently flexible (40 cN/dtex or less), the invention prevents needle hole opening without increasing graft wall thickness, thereby maintaining low profile capabilities.
Solution Approach 2:
Instead of using rigid grommets that copy the function of blocking needle holes through thickness, the invention uses a flexible suture thread that copies the function through elasticity, achieving the same endoleak prevention without the thickness penalty.
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 design achieves a low profile stent graft that reduces vascular damage, extends treatment applicability to patients with narrower arteries, and minimizes the risk of type III endoleak by maintaining needle hole integrity under long-term blood pressure.
Implementation Method 1
the suture thread has a modulus of elasticity of 40 cN/dtex or less
Data Source
AI summary
A low-profile stent graft has a Type-III endoleak suppression effect, avoiding the problem with a stent graft which uses an extra-thin graft incurring enlarged needle holes or needle hole parts in a suture part. The stent graft has a proximate end, a distal end, and a lumen which is positioned between the proximate end and the distal end. The stent graft is formed by coupling a cylindrical graft to a stent with a suture. The cylindrical graft is formed from a fabric having a thickness of 10-90 μm. The elastic modulus of the suture is 40 cN/dtex or less.