Helical Stent With Intermediate Non-Helical Ring For Stability
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Solution Overview
Problem
Existing stent designs face challenges such as instability, non-uniform expansion, and difficulty in accurate placement due to thin-walled materials, leading to issues like buckling, thrombosis, and recoil, which complicates vessel patency maintenance and drug delivery.
Innovation Solution
A flexible stent design featuring a helical section with longitudinally oriented strut members and circumferentially oriented hinge members, providing radial strength and uniform expansion while allowing for controlled drug delivery, formed from materials like cobalt chromium or nickel titanium alloys.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If thin-walled materials are used to reduce expansion forces, then expansion forces are within acceptable levels, but the stent becomes invisible on fluoroscopic equipment and difficult to place accurately
Solution Approach 1:
The stent incorporates radio-opaque markers at specific locations (ends and intermediate positions) while maintaining thin-walled construction throughout. This allows the overall structure to remain flexible and low-force while providing localized visibility for accurate placement and tracking during the procedure.
2Force
If thin-walled tubular designs are used, then expansion forces are reduced, but the struts become unstable and buckle during expansion
Solution Approach 1:
The stent uses composite construction combining thin-walled tubular elements with internal support structures and radio-opaque reinforcement. This allows the outer wall to remain thin for low expansion forces while internal elements provide structural stability to prevent buckling during expansion.
Solution Approach 2:
The stent employs curved and helical strut configurations rather than straight tubular sections. The curved geometry distributes stress more evenly during expansion, preventing localized buckling while maintaining overall structural integrity with thinner walls.
3Force
If thin-walled materials are used, then expansion forces are within acceptable levels, but the stent exhibits large elastic recovery (recoil) after expansion
Solution Approach 1:
The stent combines thin-walled construction with embedded high-strength reinforcement elements and radio-opaque markers that provide dimensional stability. This composite structure reduces overall expansion forces while preventing excessive elastic recovery through the reinforcing framework.
Solution Approach 2:
The stent is divided into multiple segments or cells with individual struts and connecting elements. This segmentation allows each component to be optimized for low expansion force while the collective structure provides dimensional stability through the interconnected geometry.
4Ease of operation
If the stent is designed to be flexible for introduction, then delivery is facilitated, but maintaining patency after expansion becomes difficult
Solution Approach 1:
The stent features dynamic geometry with articulated joints and flexible connecting elements that allow bending and compression during delivery, then transition to a rigid expanded configuration for patency maintenance. The structure adapts its mechanical properties based on the operational phase.
Solution Approach 2:
The stent uses curved and helical geometries that naturally provide flexibility when compressed or bent during delivery, but expand to form stable cylindrical or near-cylindrical structures when deployed, maintaining vessel patency through their three-dimensional geometry.
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 achieves stable vessel patency and consistent drug delivery with reduced material strain and improved placement accuracy, minimizing the risk of complications like thrombosis and recoil.
Implementation Method 1
formed from materials like cobalt chromium or nickel titanium alloys
Implementation Method 2
these designs must use very thin-walled materials (e.g., stainless steel tubing with 0.0025 inch thick walls)
Data Source
AI summary
The present invention relates to tubular stents that are implanted within a body lumen. The stent has a cylindrical shape defining a longitudinal axis and includes a helical section and a closed endless ring section within the helical section. The helical section has of a plurality of longitudinally oriented strut members and a plurality of circumferentially oriented hinge members connecting circumferentially adjacent strut members to form a band, the band being wrapped about the longitudinal axis in a substantially helical manner to form a plurality of helical windings. The closed ring section interrupts the repeating helical pattern and separates the helical section into a proximal helical section and a distal helical section. The intermediate ring section includes a plurality of longitudinally oriented strut members and a plurality of circumferentially oriented hinge members connecting circumferentially adjacent strut members to form an endless ring.