Helical Stent With Coil Interconnects For Flexibility
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Solution Overview
Problem
Conventional stents face mechanical failures due to strain and fatigue from substantial flexing and bending after deployment, as they lack sufficient flexibility and radial strength in their expanded state, leading to potential failure in applications like the superficial femoral artery.
Innovation Solution
A self-expanding stent design featuring a helical strut band interconnected by coil elements, with a specific geometric relationship between the helical strut band and coil elements, providing flexibility, stability, and radial strength, allowing for diameter changes while maintaining connectivity at any size state, and made from superelastic nitinol material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional stent structure is used, then radial strength is provided, but flexibility after deployment is insufficient leading to mechanical failure
Solution Approach 1:
The stent is divided into discrete struts connected by ring elements, creating modular segments that can flex independently while maintaining overall structural integrity. This segmentation allows the stent to bend and flex without compromising radial strength, as each segment can move relative to others while the ring elements maintain connectivity.
Solution Approach 2:
The stent employs a composite structure combining struts made of one material with ring elements made of another material, creating a multi-material construct that leverages the advantageous properties of each material. This composite approach enables simultaneous achievement of radial strength from rigid struts and flexibility from appropriately designed ring elements.
2Ease of operation
If stent is designed for flexibility in crimped state, then delivery is facilitated, but flexibility after deployment is compromised
Solution Approach 1:
The stent structure is designed to be dynamic rather than static, with ring elements that can deform and struts that can rotate relative to each other. This dynamic design allows the stent to transition from a flexible crimped state for delivery to a stable expanded state for deployment, maintaining flexibility in both configurations through appropriate geometric relationships between components.
Solution Approach 2:
The stent utilizes changes in geometric parameters during deployment, where the expansion ratio and configuration of ring elements relative to struts are specifically designed to maintain flexibility across different states. The geometric relationship between ring elements and struts is optimized to ensure flexibility is preserved whether the stent is in a crimped delivery state or an expanded deployed state.
3Reliability
If coil elements are added to interconnect helical strut band, then flexibility and stability are improved, but structure complexity increases
Solution Approach 1:
The ring elements are merged with the helical strut band configuration, where the ring elements are positioned at specific intervals along the helical struts to create an integrated structure. This merging approach provides the necessary flexibility and stability while minimizing additional complexity, as the ring elements work in conjunction with the existing helical strut geometry rather than adding separate complex mechanisms.
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 flexibility and stability, enabling it to withstand significant biomechanical forces and repeated flexing without mechanical failure, ensuring long-term functionality in vascular applications by maintaining structural integrity and facilitating crimping and expansion processes.
Implementation Method 1
The stent of the present invention is a self expanding stent made from superelastic nitinol
Implementation Method 2
A self expanding stent is designed, through choice of material, geometry, or manufacturing techniques, to expand from the crimped state to an expanded state once it is released into the intended vessel
Data Source
AI summary
The stent of the present invention combines a helical strut band interconnected by coil elements. This structure provides a combination of attributes that are desirable in a stent, such as, for example, substantial flexibility, stability in supporting a vessel lumen, cell size and radial strength. The structure of the stent of the present invention provides a predetermined geometric relationship between the helical strut band and interconnected coil elements in order to maintain connectivity at any diameter size state of the stent.