Polymeric Heart Valve Leaflet Geometry for Low Pressure Loss
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Solution Overview
Problem
Existing polymeric heart valves suffer from high forward flow pressure loss and incomplete leaflet opening due to leaflet thickness that is insufficiently thick, leading to asymmetric flow patterns and potential thrombosis.
Innovation Solution
The development of polymeric heart valves with leaflets designed in a partially open position at rest, featuring a specific thickness profile and sinus lobes, achieved through the use of a tapered form to maintain leaflets in this position and subsequent annealing, ensuring symmetric opening and reduced forward flow pressure loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If leaflets are made sufficiently thick to produce durable valves, then valve durability is improved, but forward flow pressure loss increases and leaflet opening becomes incomplete
Solution Approach 1:
The patent applies local quality by creating a non-uniform thickness distribution across the leaflet. The leaflet has a first thickness at the free edge and a second, greater thickness at the base region. This allows the leaflet to be thick enough at the base for durability and structural support, while being thinner at the free edge to reduce flow resistance and prevent excessive pressure loss during forward flow.
Solution Approach 2:
The leaflet is segmented into distinct regions with different thickness characteristics. The base region has greater thickness for structural integrity, while the free edge region has lesser thickness for optimized flow. This segmentation allows each region to perform its specific function optimally without compromising the other.
2Reliability
If leaflets are made sufficiently thick to produce durable valves, then valve durability is improved, but leaflet opening becomes incomplete
Solution Approach 1:
The varying thickness distribution enables the leaflet to open completely during valve operation. The thinner free edge region allows the leaflet to deflect and open more easily, while the thicker base region maintains structural integrity and durability. This local quality differentiation resolves the contradiction between durability and complete opening.
3Reliability
If leaflets are made sufficiently thick to produce durable valves, then valve durability is improved, but asymmetric flow patterns occur leading to potential thrombosis
Solution Approach 1:
The non-uniform thickness distribution creates symmetric flow patterns by optimizing the flow characteristics across different regions of the leaflet. The thinner free edge region allows blood flow to pass symmetrically, preventing turbulent flow and asymmetric flow patterns that could lead to thrombosis, while maintaining durability through the thicker base region.
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 solution results in low forward flow pressure loss, symmetric leaflet opening, and improved hemocompatibility by preventing thrombosis, enhancing the reliability and performance of the valve.
Implementation Method 1
inserting a tapered form into the conduit to maintain the at least three leaflets in a partially open position
Implementation Method 2
heating the polymeric valve to fix the rest position of the at least three leaflets in the partially open position
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
A polymeric heart valve (100) is disclosed which includes a valve body having a central axis and including a conduit extending along the central axis from an inflow end to an outflow end; and at least three flexible leaflets (130) extending from the body into the conduit, each of the leaflets defining an attachment curve with the body. Respective pairs of leaflets each define a commissure located proximal the body. The at least three leaflets define a partially open position at rest, a fully open position deflecting away from the central axis during forward blood flow along a direction from the inflow end to the outflow end, and a closed position deflecting toward the central axis during reverse blood flow along a direction from the outflow end to the inflow end.