Asymmetric Leaflet Geometry for Prosthetic Valve Flow Control
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Solution Overview
Problem
Bioprosthetic valves face challenges with blood stagnation and clot formation due to the flexible nature of leaflets, which can lead to inefficient movement and potential thrombus formation, especially near the leaflet attachment to the support structure.
Innovation Solution
The design incorporates leaflets with asymmetric geometry, where one side region opens less than the other, creating a spiral flow pattern that enhances blood flow and reduces stagnation, and allows for controlled asymmetric movement to minimize crease formation and facilitate faster closure, thereby reducing the risk of clot formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If flexible leaflets are used to mimic native valve function, then the valve can open and close under fluid pressure influence, but blood stagnation occurs behind the leaflet when open, causing clot formation at the leaflet base
Solution Approach 1:
The patent applies asymmetry by configuring the leaflet attachment zone with three sides of an asymmetric acute trapezoid, where the attachment zone has different dimensions on each side. This asymmetric geometry causes the leaflet to open and close in an asymmetric manner, preventing blood stagnation behind the leaflet while maintaining flexible operation. The asymmetric attachment zone creates differential movement patterns that eliminate stagnant regions.
2Ease of manufacture
If symmetric leaflet design is used, then manufacturing is simplified, but blood flow stagnation occurs and clot formation risk increases
Solution Approach 1:
The patent deliberately introduces asymmetry in the attachment zone geometry (three sides of an asymmetric acute trapezoid) to prevent blood stagnation and clot formation. This asymmetric design, while slightly more complex to manufacture, significantly improves reliability by eliminating stagnant blood flow regions that would otherwise lead to thrombus formation.
3Productivity
If leaflets are fully flexible to reduce closing volume, then valve operation is improved, but uncontrolled leaflet movement causes blood stagnation near attachment
Solution Approach 1:
The asymmetric acute trapezoid attachment zone configuration provides controlled asymmetric movement of the leaflet. This control mechanism allows the leaflet to maintain flexibility for reduced closing volume while preventing uncontrolled movement that would cause blood stagnation near the attachment zone.
Solution Approach 2:
The patent applies local quality by creating different geometric properties at different locations of the attachment zone. The asymmetric acute trapezoid configuration provides different attachment characteristics on each side of the leaflet, enabling localized control of leaflet movement to prevent stagnation while maintaining overall flexibility.
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
This design improves blood flow dynamics, reduces the risk of thrombus formation by minimizing blood stagnation and enhancing the leaflet's closing efficiency, ensuring a more uniform opening and consistent operation across various loading conditions.
Implementation Method 1
The leaflets move under the influence of fluid pressure. In operation, the leaflets open when the upstream fluid pressure exceeds the downstream fluid pressure and close when the downstream fluid pressure exceeds the upstream fluid pressure.
Implementation Method 2
The free edges of the leaflets coapt under the influence of downstream fluid pressure closing the valve to prevent downstream blood from flowing retrograde through the valve.
Data Source
AI summary
Described embodiments are directed toward prosthetic valves having leaflets that move asymmetrically in that in the fully open position, the leaflet first side region opens less than the leaflet second side region. Asymmetric opening and final open position, in synchrony with the other leaflets having similar motion and final open position creates spiral flow exiting the open valve that may, among other things, increases blood flow on the downstream side of the leaflet and thus reduces stagnation of the blood that might lead to thrombus formation. Controlled asymmetric movement of the leaflet reduces closing volume by initiating closure on the leaflet first side region and finishing closures on the leaflet second side region.