Medical Stent Crown Tabs and Zigzag Porosity
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Solution Overview
Problem
Current stents face challenges in flexibility, expansion ratio, structural support, minimizing metal fatigue, low profile, and thrombi formation when treating neurovascular aneurysms and atherosclerosis, particularly due to issues with zigzag elements that can deform or jam during delivery, causing vessel damage.
Innovation Solution
A stent design featuring a tubular structure with zigzag portions and crown elements, where tabs are coupled to a subset of crown elements in an offset configuration, allowing radial expansion and minimizing vessel injury, with a porosity of 50-95% and 'flat' bends to reduce stress concentration and improve tracking through tortuous vessels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If zigzag elements are used to form the stent body, then flexibility for navigating tortuous vessels is improved, but the elements may twist or bend outward during delivery, making deployment difficult and increasing risk of vessel damage
Solution Approach 1:
The stent is divided into multiple crown elements connected by elongate portions with zigzag configurations. Each crown element can be independently positioned and controlled during delivery, allowing the stent to navigate tortuous vessels while maintaining controlled deployment. The segmentation enables the stent to flex and conform to vessel geometry without the entire structure twisting or bending outward uncontrollably.
Solution Approach 2:
The stent is pre-formed with a compressed configuration that maintains the zigzag elements in a controlled, non-twisted state during delivery. The crown elements are pre-positioned relative to each other, preventing outward bending before deployment. This preliminary configuration allows the stent to be delivered through tortuous vessels while avoiding the deployment difficulties and vessel damage risks associated with uncontrolled element movement.
2Volume of moving object
If the stent is designed to expand from inner-lumen diameter to target site diameter, then expansion ratio of at least twofold is achieved, but structural support and metal fatigue resistance become challenging
Solution Approach 1:
The elongate portions connecting crown elements are designed with specific zigzag configurations that provide localized flexibility and stress distribution. The crown elements themselves are structured with struts arranged to optimize both expansion capability and fatigue resistance. This local quality differentiation allows different parts of the stent to perform specialized functions: the zigzag portions handle flexing during navigation while the crown element structures provide structural support during expansion and长期使用.
Solution Approach 2:
The stent utilizes a composite structure combining multiple crown elements with zigzag-configured elongate portions, creating a composite mechanical system that achieves both high expansion ratio and fatigue resistance. The interaction between the crown elements and elongate portions creates a composite structure that distributes stress more effectively than a uniform design, enabling the stent to expand twofold or more while maintaining metal fatigue resistance through optimized stress distribution.
3Strength
If crown elements are formed at the ends of the stent, then structural support is improved, but the elements may cause injury to vessel wall and make deployment difficult
Solution Approach 1:
The crown elements are designed to transition dynamically from a compressed, low-profile configuration during delivery to an expanded, structurally supportive configuration after deployment. During delivery, the crown elements are contained within the delivery catheter in a compact form that minimizes vessel wall contact and injury risk. After deployment, the crown elements expand to provide the necessary structural support at the vessel ends, maintaining vessel patency without causing harm.
Solution Approach 2:
The crown elements are nested within the delivery catheter during delivery, allowing the stent to be delivered through tortuous vessels with minimal vessel wall interaction. The nested configuration protects the crown elements from causing vessel wall injury during delivery. Upon deployment, the crown elements are released from the nested state and expand to provide structural support, separating the delivery phase (low profile, minimal injury risk) from the functional phase (high structural support).
Data Source
AI summary
A stent configured for implantation in a body lumen, includes: a tubular structure having a first end, a second end opposite from the first end, and a tubular body extending between the first and second ends, the tubular body comprising a plurality of elongate portions defining a porosity for the stent, at least one of the elongate portions having a zig-zag configuration, the first end of the tubular structure having a plurality of crown elements disposed circumferentially with respect to a longitudinal axis of the tubular structure, the crown elements forming a crown configuration for the first end of the tubular body; and a plurality of tabs coupled to the first end of the tubular structure; wherein a number of the crown elements is higher than a number of the tabs; wherein the tabs are coupled to only a subset, and not all, of the crown elements.