Artificial Cardiac Valve Segmented Stent Design
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Solution Overview
Problem
Existing artificial cardiac valves face issues of insufficient support leading to breakage, unsatisfactory match with native valve anatomy causing displacement and paravalvular leaks, and long lengths causing left ventricular outflow tract obstruction.
Innovation Solution
An artificial cardiac valve design featuring an outer stent with sequentially connected first, second, and third stent segments, including a cylindrical mesh tube inner stent and a D-shaped mesh tube second stent segment, a flared third stent segment, and barbs for anchoring, which matches the native valve anatomy and withstands traction forces, preventing displacement and obstruction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a single stent structure is used, then the device is simpler, but it provides insufficient support leading to breakage
Solution Approach 1:
The stent is divided into multiple segments (first stent segment, second stent segment, third stent segment) connected sequentially. Each segment serves specific functions: the first segment provides anchoring in the ventricle, the second D-shaped segment matches the valve annulus anatomy, and the third flared segment anchors in the atrium. This segmentation resolves the contradiction by distributing mechanical loads across multiple segments, providing sufficient support strength while maintaining reasonable structural complexity.
Solution Approach 2:
The inner stent is nested within the outer stent, creating a dual-stent structure. The inner stent provides additional structural support and serves as the attachment framework for the valve leaflets, while the outer stent provides anchoring and structural framework. This nested configuration resolves the contradiction by combining multiple support functions in a compact integrated structure, enhancing overall strength without excessive complexity increase.
2Reliability
If a standard cylindrical stent is used, then manufacturing is easier, but it does not match native valve anatomy leading to displacement and paravalvular leaks
Solution Approach 1:
Different segments of the stent have different geometric qualities tailored to specific anatomical locations: the first segment is cylindrical for ventricular anchoring, the second segment is D-shaped to match the mitral valve annulus anatomy, and the third segment is flared for atrial anchoring. This local quality differentiation resolves the contradiction by optimizing each segment's geometry for its specific function, ensuring reliable anchoring and anatomical matching while maintaining manufacturability through standardized fabrication techniques.
Solution Approach 2:
The second stent segment features an asymmetric D-shaped cross-section rather than a symmetric circular shape. This asymmetry allows the stent to conform to the non-circular anatomy of the mitral valve annulus, improving anatomical matching and preventing displacement. The asymmetric design resolves the contradiction by enhancing reliability through better anatomical conformity while remaining manufacturable using conventional forming processes.
3Reliability
If the stent is made longer to improve anchoring, then anchoring is better, but it causes left ventricular outflow tract obstruction
Solution Approach 1:
The stent length is divided into three functional segments with specific length allocations: the first segment extends into the ventricle for anchoring without obstructing the outflow tract, the second segment spans the valve annulus, and the third segment extends into the atrium. This segmentation resolves the contradiction by distributing the anchoring function across multiple segments positioned in different locations, achieving reliable anchoring while preventing outflow tract obstruction through proper segment length design.
Solution Approach 2:
The stent achieves enhanced anchoring reliability not by increasing length in one dimension, but by utilizing multiple spatial dimensions and orientations through the three-segment configuration. The segments are oriented at different angles and positions, with the first segment angled to anchor in the ventricle without blocking the outflow tract, the second segment conforming to the annulus, and the third segment anchoring in the atrium. This multi-dimensional approach resolves the contradiction by achieving reliable anchoring through spatial distribution rather than simply increasing overall length.
Data Source
AI summary
An artificial cardiac valve is disclosed, which includes an outer stent; an inner stent nested within and connected to the outer stent; leaflets disposed inside the inner stent; and membranes attached to walls of the outer and inner stents. The inner stent is a cylindrical mesh tube, and the outer stent includes a first stent segment, a second stent segment and a third stent segment which are connected sequentially. The first stent segment is a mesh tube. The second stent is a mesh tube having a substantially D-shaped cross-section, and the third stent segment is a flared mesh tube. The first stent segment has a maximum diameter that is equal to a diameter of the second stent segment and to a minimum diameter of the third stent segment. In this stent design, the inner stent can withstand traction forces from the leaflets, and the outer stent is adapted to match the anatomy of the native valve. As a result, after release, the artificial cardiac valve will seldom experience displacement and be rarely associated with paravalvular leaks. Moreover, it has a prolonged service life.