Valve Prosthesis Stent Resisting Vessel Recoil
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Solution Overview
Problem
Current valve prostheses for pulmonary valve substitution are invasive, prone to reflux, and unable to resist recoil forces of blood vessels, particularly in pediatric patients, and existing solutions like xenografts degrade over time.
Innovation Solution
A valve prosthesis with a monocusp sail-like structure and a lattice stent that expands to resist recoil forces, providing a biocompatible and minimally invasive solution for implantation, using materials like ePTFE and nitinol, with a design that allows for easy percutaneous insertion and anchoring in the pulmonary trunk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If xenografts or homografts are used for valve implantation in pediatric patients, then the valve can be implanted with biological compatibility, but the implant degrades over time due to biological material limitations
Solution Approach 1:
The invention combines biocompatible synthetic materials (ePTFE for the valve leaflet) with a metal stent structure (nitinol or stainless steel), creating a composite implant that merges the advantages of biological compatibility with the durability and structural integrity of synthetic materials, eliminating the degradation issue of pure biological grafts
Solution Approach 2:
The invention changes the material parameters from biological origin to synthetic biocompatible materials, specifically using expanded polytetrafluoroethylene (ePTFE) which exhibits superior resistance to degradation while maintaining blood compatibility, thus extending the implant's operational lifespan
2Reliability
If ePTFE sheet is used for valve reconstruction, then the material is not subject to wear, but the application requires open heart operation in extracorporeal circulation which is invasive and complex
Solution Approach 1:
The valve leaflet is nested within the stent structure, and the entire assembly is nested within a delivery catheter for percutaneous insertion. This nested configuration allows the complex valve-stent system to be delivered through a minimally invasive catheter rather than requiring open heart surgery
Solution Approach 2:
The stent acts as an intermediary structure that pre-forms and supports the ePTFE valve leaflet, allowing the valve to be self-contained and deliverable via catheter. The stent serves as the mediator between the valve leaflet and the delivery system, enabling percutaneous implantation
3Ease of operation
If a stent is expanded in a blood vessel using angioplasty balloon, then the stent can be percutaneously inserted, but recoil forces from the blood vessel reduce the cross section and decrease effectiveness
Solution Approach 1:
The valve leaflet is pre-formed and attached to the stent structure before delivery. This preliminary configuration ensures that when the stent expands, the valve is already in its functional position and orientation, preventing reflux and maintaining effectiveness despite vessel recoil
Solution Approach 2:
The combination of the stent's radial strength with the valve leaflet's structural integrity creates a composite system that resists recoil forces more effectively than a stent alone, maintaining the cross-sectional area and preventing vessel collapse
4Strength
If a valve prosthesis is designed to resist recoil forces, then the implant can maintain its structure, but the device becomes more complex and difficult to implant percutaneously
Solution Approach 1:
The stent is designed with dynamic expandability, transitioning from a compressed delivery state to an expanded functional state. This dynamic design allows the structure to achieve high recoil resistance only when needed (after implantation), while maintaining simplicity during delivery through the catheter
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 enables a minimally invasive, durable, and effective valve prosthesis that maintains blood flow harmony with cardiac cycles, reducing the risk of reflux and embolism, suitable for pediatric patients, and can last for at least 10 years without defects.
Implementation Method 1
a stent (2) composed of a lattice having a configured structure so as to be expandable from a compressed state in which it occupies a minimum space, so that it can be percutaneously inserted with its valve, and transported through the body ducts, to an expanded state in which it is completely expanded and rigid, so to be anchored to the destination blood vessel... capable of resisting the recoil forces that the blood vessel imposes on the stent
Implementation Method 2
the tissue having a suitable softness and resistance so that it can be deformed from a closed state to an open state in order to permit the body fluid, in particular blood, to exert a pressure on this valve structure
Data Source
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AI summary
The present invention regards a valve prosthesis (1; 40; 50; 60) comprising a stent (2) and characterised in that it comprises a valve (3) arranged in said stent (2) and bound thereto in at least one preestablished zone so that it can be deformed between a closed state in which said valve (3) is fully spread out in the stent (2), thus blocking the passage of a body fluid, and an open state in which said valve (3), due to the pressure of said body fluid, is substantially collapsed on an inner wall of said stent (2), thus permitting the flow of said body fluid. The invention also regards a method for making said valve prosthesis.