Heart Valve Frame Correction With Cobalt-Chromium Assist Stent
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Solution Overview
Problem
Transcatheter heart valves with nickel-titanium frames often deform post-implantation due to insufficient radial force, leading to defective valve leaflet performance and paravalvular leaks, as existing methods like balloon re-expansion are ineffective in maintaining the frame's shape.
Innovation Solution
An assist stent device with a cobalt-chromium frame is deployed inside the deformed nickel-titanium frame to re-shape and secure the skirt section against the aortic annulus, utilizing the stiffer material to support and correct the deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a nickel-titanium frame is used for the transcatheter heart valve, then the frame is self-expanding and flexible, but the radial force is low and the frame easily migrates or deforms
Solution Approach 1:
The patent combines nickel-titanium frame with cobalt-chromium assist stent to create a composite structure. The nickel-titanium provides self-expanding capability and flexibility, while the cobalt-chromium assist stent reinforces the frame to increase radial force and prevent deformation, resolving the contradiction between adaptability and strength.
Solution Approach 2:
The assist stent is nested within the transcatheter heart valve frame structure. The cobalt-chromium assist stent is positioned inside the nickel-titanium frame, with the frame expanding around the assist stent during deployment. This nested configuration allows the assist stent to reinforce the frame without interfering with the self-expanding mechanism.
2Ease of repair
If balloon re-expansion is used to reshape the nickel-titanium frame, then the frame can be re-expanded, but the frame easily deforms again after implantation
Solution Approach 1:
The assist stent is pre-positioned within the frame before final deployment. This preliminary placement of the cobalt-chromium assist stent provides continuous structural support that prevents the nickel-titanium frame from deforming again after initial expansion, ensuring long-term shape stability while maintaining the ability to perform re-expansion if needed.
3Stability of the object's composition
If the frame radial force is increased to prevent deformation, then the frame stability improves, but the flexibility and self-expanding capability are reduced
Solution Approach 1:
The patent uses a composite structure where the nickel-titanium frame maintains its self-expanding flexibility while the cobalt-chromium assist stent provides the necessary radial force and stability. The two materials work together, with the nickel-titanium enabling expansion and the cobalt-chromium preventing deformation, thus resolving the contradiction between stability and adaptability.
Solution Approach 2:
The nested configuration allows the assist stent to be contained within the frame structure during deployment. The nickel-titanium frame expands around the cobalt-chromium assist stent, enabling the frame to maintain its self-expanding capability while the inner assist stent provides the reinforcing support needed for stability.
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 cobalt-chromium assist stent effectively re-shapes and supports the deformed skirt section, ensuring optimal valve leaflet function with no leaks, prolapse, or regurgitation, thereby avoiding the need for valve replacement.
Implementation Method 1
The frame on this type of heart valve is self-expanding, but because the radial force of a nickel-titanium frame is low and because nickel-titanium is a flexible material, the frame can easily migrate from its implanted position, or can be easily deformed
Implementation Method 2
the radial force of a nickel-titanium frame is not strong enough (i.e., it is usually between 15 newton/bls and 25 newton/bls) to ensure a uniform cylindrical expansion
Data Source
AI summary
A method is provided for repairing an implanted heart valve prosthesis, wherein the heart valve prosthesis has a deformed skirt section that is positioned at a native valve annulus, and a valve section which has a plurality of leaflets. An assist stent device is provided having an annular frame surrounded by an annular tissue assembly, wherein the annular frame has a generally cylindrical body made of cobalt-chromium having a plurality of rows of cells. The assist stent device is delivered to the native valve annulus, and aligned inside the skirt section. The assist stent device is then expanded until the assist stent device engages the skirt section and secures the skirt section against the native valve annulus.