Contoured Bioprosthetic Valve Tissue for Pannus-Resistant Cell Migration
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Solution Overview
Problem
Bioprosthetic heart valves made from biological tissue face complications such as calcification and pannus formation, which can lead to obstructive valve failure due to the growth of granulation tissue, and there is no reliable way to predict or prevent pannus overgrowth, especially in minimally-invasive or percutaneously-deliverable valves where additional material bulk is undesirable.
Innovation Solution
A contoured biological tissue with a predetermined pattern of ridges or depressions is used for bioprosthetic heart valves, oriented to facilitate cellular migration in one direction and discourage it in another, with adjacent features spaced at least 10 microns apart to prevent fibroblast migration, and the tissue is treated with crosslinking and dehydration methods, including laser contouring and glycerin-based solutions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If longer housing cylinders are used to create an ingrowth barrier, then pannus formation is prevented, but the delivery profile increases and minimally-invasive delivery becomes impractical
Solution Approach 1:
The patent transitions from preventing pannus formation through axial extension (longer housing cylinders) to preventing it through surface topography modifications (ridges and grooves on the valve surface). This dimensional shift allows the same protective function to be achieved without increasing the overall valve volume or delivery profile.
Solution Approach 2:
Instead of uniformly increasing the housing cylinder length throughout the valve structure, the patent applies localized surface features (ridges and grooves) only at specific locations on the valve leaflets and housing where pannus formation is most problematic. This localized approach prevents pannus overgrowth without adding bulk to the entire valve.
2Reliability
If additional features or structures are added to prevent tissue ingrowth, then pannus formation is reduced, but the material bulk of the valve increases
Solution Approach 1:
The patent divides the valve surface into segmented patterns of ridges and grooves rather than using a continuous solid barrier. This segmentation approach creates multiple small obstacles to tissue ingrowth that collectively prevent pannus formation without requiring large amounts of additional material.
Solution Approach 2:
The ridge and groove pattern creates a micro-topography that functions similarly to porous structures by creating physical barriers to cell migration while maintaining overall valve integrity. The patterned surface allows controlled interaction with surrounding tissue while preventing unwanted ingrowth, without adding significant material bulk.
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 contoured pattern effectively reduces or eliminates pannus overgrowth that interferes with valve functioning, enhancing the durability and reducing the likelihood of obstructive heart valve failure by directing cellular migration and preventing tissue ingrowth into the valve orifice.
Implementation Method 1
The contouring can be performed with a laser, preferably a femtosecond laser
Implementation Method 2
The biological tissue can be at least partially crosslinked
Implementation Method 3
The biological tissue can be at least partially crosslinked, and/or at least partially dehydrated, such as with a glycerin-based treatment solution
Data Source
AI summary
A contoured biological tissue for a bioprostheses, such as a cardiac/vascular patch or a bioprosthetic heart valve, and methods of contouring the tissue, are described. A predetermined pattern is provided on the tissue, comprising a plurality of ridges or depressions that are configured to facilitate cellular migration in a first direction and discourage cellular migration in a second direction. The biological tissue can be used in connection with a bioprosthetic heart valve comprising a biological tissue leaflet structure coupled to a supporting frame.