Nested Double-Layer Stent for Flexible, Uniform Vascular Expansion
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Solution Overview
Problem
Existing stents face challenges such as restenosis, reocclusion, thrombosis, and vascular damage due to high bending stiffness and poor shape followability, especially when used to expand vascular lumens, and they are difficult to deploy in thin catheters due to increased surface area.
Innovation Solution
A stent with a double-layer structure comprising a first stent body and a second stent body, where the second stent body is inserted into the first stent body, allowing for increased surface area without excessive bending stiffness, and both bodies are independently deformable, enhancing shape followability and diameter reducibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the surface area of the stent is increased to more uniformly expand the narrowed blood vessel, then the expansion uniformity is improved, but the bending stiffness becomes too high, leading to poor shape followability to a vascular structure
Solution Approach 1:
The stent is divided into multiple struts arranged in a grid pattern, creating a segmented structure with numerous small cells. This segmentation allows the stent to achieve uniform expansion through the distributed support of multiple struts while maintaining flexibility, as each strut can independently deform to follow the vascular geometry.
Solution Approach 2:
The stent employs a nested cell structure where smaller cells are formed within the framework of larger cells. This multi-scale nested architecture increases the surface area and structural complexity for uniform expansion while the hierarchical design maintains overall flexibility and shape followability.
2Manufacturing precision
If the surface area (the area excluding the area of the cell holes) of the stent is increased, then the expansion uniformity is improved, but the volume of the stent increases, and for this reason, it is difficult to sheathe the narrowed stent in a thin catheter
Solution Approach 1:
The stent is designed with a porous grid structure containing numerous cell holes distributed throughout its surface. This porous architecture increases the effective surface area for uniform vascular expansion while the presence of void spaces reduces the overall material volume, enabling the stent to be compressed into thin catheters for delivery.
3Reliability
If the stent is used to expand a vascular lumen, then the patency of the blood vessel is ensured, but there is a probability that restenosis or reocclusion occurs in a blood vessel after implantation of the stent or a complication such as a thrombosis occurs
Solution Approach 1:
The porous grid structure with cell holes allows for improved blood flow dynamics and reduced stent-blood interaction, which may decrease the risk of thrombosis and restenosis while maintaining vessel patency. The porous design promotes endothelialization and reduces turbulence in the blood flow.
Solution Approach 2:
The stent combines multiple materials with complementary properties: a shape memory alloy framework provides structural support and patency maintenance, while a biodegradable polymer coating delivers antiproliferative drugs to prevent restenosis and reduce thrombosis risk, creating a composite structure that addresses multiple complications simultaneously.
4Manufacturing precision
If a balloon is used for expanding a vascular lumen, then the blood vessel is temporarily closed, but for this reason, there is a probability that infarction particularly in a distal side blood vessel occurs
Solution Approach 1:
The stent utilizes shape memory alloy with dynamic phase transformation properties, allowing it to transition from a compressed state during catheter delivery to an expanded state at the implantation site. This dynamic behavior enables self-expansion without balloon occlusion, maintaining blood flow and preventing distal infarction.
Data Source
Figure 1
Figure 2
Figure 3A~3C
AI summary
A stent 1 which is inserted into a catheter and extruded from the catheter into a blood vessel to dilate a blood vessel, wherein the stent is equipped with a first stent body 10 in which a plurality of first cells comprising struts arranged in a frame shape are spread in the circumferential direction and are contiguous in the central axial direction and a second stent body 20, interpolated into the first stent body, in which a plurality of second cells comprising struts arranged in a frame shape are spread in the circumferential direction and are contiguous in the central axial direction, and, in a state in which the second stent body 20 is interpolated into the first stent body 10, the intersecting portions of the second cells are arranged in the hole portions of the first cells and the first stent body 10 and the second stent body 20 are not connected to each other in the radial direction.