Toggle Lock Struts for Stent Mechanical Strength
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Solution Overview
Problem
Current stents, both metallic and polymeric, face challenges such as embolic debris release during deployment, restenosis, and mechanical strength limitations, which affect the patency of blood vessels and require additional treatments like anticoagulants or thicker struts that increase profile and injury to the vessel wall.
Innovation Solution
A tubular stent design featuring cylindrical rings connected by toggle lock struts that bend and lock in a straight configuration upon radial expansion, providing increased mechanical strength and resistance to compressive forces, thus reducing recoil and vessel occlusion risks while maintaining a low profile for delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If polymeric stents use thicker struts to improve mechanical strength and reduce recoil, then mechanical strength is improved, but the profile increases and vessel injury increases
Solution Approach 1:
The stent combines bioresorbable polymer material with a toggle lock mechanical structure to achieve high mechanical strength without requiring thick struts. The composite design integrates the polymer matrix with the toggle lock mechanism, allowing thin-strut construction while maintaining structural integrity and resistance to recoil forces.
Solution Approach 2:
The toggle lock structure introduces dynamic mechanical behavior to the stent struts. The struts can toggle between locked and unlocked states, providing adaptive mechanical support that enhances strength where needed while maintaining flexibility and low profile during delivery. This dynamic mechanism allows thin struts to achieve the mechanical performance of thicker struts.
2Strength
If metallic stents are used to provide high mechanical strength and low profile, then mechanical strength is improved, but embolic debris release occurs during deployment
Solution Approach 1:
The invention changes the material parameter from permanent metal to bioresorbable polymer, which fundamentally alters the deployment mechanics. The polymer material is more compliant and less likely to cause plaque fracture and embolic debris release during expansion, while the toggle lock mechanism compensates for the lower inherent strength of the polymer material.
Solution Approach 2:
The toggle lock mechanism replaces the reliance on thick metallic struts for mechanical strength. Instead of using metal's inherent high strength, the invention uses a mechanical locking system that engages to provide the necessary structural support, allowing the use of thinner, more compliant polymer struts that are less traumatic to the vessel wall during deployment.
3Reliability
If bioresorbable polymers are used to create stents, then restenosis is reduced, but mechanical strength and resistance to recoil are insufficient
Solution Approach 1:
The stent structure is segmented into multiple struts with toggle lock mechanisms at key junctions. This segmentation allows the polymer material to be used in thinner configurations while the distributed toggle lock mechanisms provide cumulative mechanical support, maintaining overall structural integrity and resistance to recoil without requiring the material itself to be stronger.
Solution Approach 2:
The toggle lock mechanism acts as an intermediary between the bioresorbable polymer struts and the vessel wall. It provides the necessary mechanical strength and recoil resistance without requiring the polymer material itself to have high strength properties, allowing the use of compliant, restenosis-resistant materials while maintaining structural performance.
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 design enhances mechanical strength, reduces recoil, and minimizes vessel occlusion, improving blood flow and reducing the risk of restenosis, while allowing for thinner struts that are easier to deliver and cause less injury to the vessel wall.
Implementation Method 1
The elbows are configured to bend when the stent is in a compressed configuration for delivery and to straighten when the stent is in an expanded configuration
Data Source
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AI summary
A tubular stent includes cylindrical rings disposed adjacent to each other and coupled to each other by a plurality of longitudinal segments. Each cylindrical ring includes circumferentially oriented toggle lock struts. The toggle lock struts include a first arm and a second arm coupled together at an elbow. When the stent is in a compressed configuration for delivery, the toggle lock struts are bent at the elbow such that the first arm is disposed at an angle of less than 180 degrees relative to the second arm. Upon radial expansion of the stent, the toggle lock struts are unbent to a straight configuration and permitted to relax slightly beyond the straight configuration to a locked configuration such that the angle between the first arm and the second arm changes from less than 180 degrees to more than 180 degrees.