Variable Cross-Section Stent for Transcatheter Valve Sealing
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Solution Overview
Problem
Transcatheter valve prostheses often experience paravalvular leakage due to gaps between the prosthetic valve and native tissue, particularly at the commissural points, which can lead to undesirable regurgitation and backflow.
Innovation Solution
A transcatheter valve prosthesis with a variable shaped cross-section, specifically a tubular stent component that transitions from a circular to a triangular cross-section along its length, conforming to the native valve leaflets' commissural points to prevent gaps and ensure a blood-tight seal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a prosthetic valve with a uniform circular cross-section is used, then the device structure is simple and easy to manufacture, but gaps form between the prosthetic valve and native tissue at the commissural points, causing paravalvular leakage
Solution Approach 1:
The prosthetic valve employs different cross-sectional shapes at different locations along its length. Specifically, the first portion has a first cross-sectional shape while the second portion has a second cross-sectional shape that differs from the first. This local variation allows the valve to conform to the non-uniform geometry of the native valve annulus and commissural points, improving sealing effectiveness without requiring complete redesign of the entire device structure.
Solution Approach 2:
The prosthetic valve is divided into multiple segments or portions along its longitudinal axis, each with potentially different cross-sectional characteristics. This segmentation enables each portion to be optimized for its specific functional requirement - such as anchoring in the annulus or sealing at the commissures - while maintaining overall device simplicity and manufacturability through modular construction approaches.
2Reliability
If the prosthetic valve cross-section matches the triangular shape of native valve leaflets, then paravalvular leakage is prevented, but the device structure becomes more complex
Solution Approach 1:
The manufacturing process utilizes parameter changes, particularly thermal effects, to transform the prosthetic valve from a compressed delivery state to an expanded deployed state with the desired variable cross-sectional geometry. The shape transformation is achieved through controlled expansion that allows the first and second portions to assume their respective cross-sectional shapes (e.g., circular to triangular transition) to match the native valve anatomy, ensuring proper sealing while maintaining ease of delivery and deployment.
3Reliability
If a variable cross-sectional design is implemented, then gaps at commissural points are occluded and regurgitation is reduced, but the device structure becomes more complex
Solution Approach 1:
The prosthetic valve employs different cross-sectional shapes at different locations along its length. Specifically, the first portion has a first cross-sectional shape while the second portion has a second cross-sectional shape that differs from the first. This local variation allows the valve to conform to the non-uniform geometry of the native valve annulus and commissural points, improving sealing effectiveness without requiring complete redesign of the entire device structure.
Solution Approach 2:
Rather than attempting to make the entire prosthetic valve structure complex to achieve sealing, the invention inverts the approach by using a relatively simple delivery configuration that transforms into the desired complex deployed geometry. The valve is delivered in a compressed state with uniform cross-section for ease of catheter delivery, then expanded in situ to achieve the variable cross-sectional shape needed for sealing, effectively solving the complexity problem through reverse sequencing of simplicity and complexity.
Data Source
AI summary
A transcatheter valve prosthesis includes a self-expanding tubular stent component and a prosthetic valve disposed within and secured to the stent component. The tubular stent component has a proximal portion, a distal portion, and an intermediate portion between the proximal and distal portions. In a compressed delivery configuration, the tubular stent component has a generally circular cross-section along its length. In an expanded deployed configuration, the proximal and distal portions have a generally circular cross-section while the intermediate portion of the stent component has a generally triangular cross-section with three vertexes that are configured to project into three commissural points of a native valve when the valve prosthesis is implanted in situ. The generally triangular transverse cross-section of the valve prosthesis is formed by pulling or extending selected or particular struts of the stent component radially outwards and then applying heat to heat-set the stent component in the deployed configuration.