Development of 3D Printed Mitral Valve Constructs for Transcatheter Device Modeling of Tissue and Device Deformation

Marija Vukicevic,Shail Maharshi Mehta,Stephen H Little,K Jane Grande-Allen

doi:10.1007/s10439-022-02927-y

Marija Vukicevic, Shail Maharshi Mehta + Show 2 more

Open Access

https://doi.org/10.1007/s10439-022-02927-y

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Abstract

Transcatheter mitral valve repair (TMVR) therapies offer a minimally invasive alternative to surgical mitral valve (MV) repair for patients with prohibitive surgical risks. Pre-procedural planning and associated medical device modeling is primarily performed in silico, which does not account for the physical interactions between the implanted TMVR device and surrounding tissue and may result in poor outcomes. We developed 3D printed tissue mimics for modeling TMVR therapies. Structural properties of the mitral annuli, leaflets, and chordae were replicated from multi-material blends. Uniaxial tensile testing was performed on the resulting composites and their mechanical properties were compared to those of their target native components. Mimics of the MV annulus printed in homogeneous strips approximated the tangent moduli of the native mitral annulus at 2% and 6% strain. Mimics of the valve leaflets printed in layers of different stiffnesses approximated the force–strain and stress–strain behavior of native MV leaflets. Finally, mimics of the chordae printed as reinforced cylinders approximated the force–strain and stress–strain behavior of native chordae. We demonstrated that multi-material 3D printing is a viable approach to the development of tissue phantoms, and that printed patient-specific geometries can approximate the local deformation force which may act upon devices used for TMVR therapies.

Highlights

Mitral valve diseases are among the most prevalent heart diseases, and their prevalence increases with age.[16]
When a nitinol transcatheter mitral valve repair (TMVR) device is deployed within a native mitral valve there are several deformation events that are expected: (i) the native mitral annulus is forced into a more circular configuration by the device; and the fully expanded device is compressed by the native annulus
The use of 3D printed materials capable of replicating patient-specific geometries while demonstrating biologically relevant mechanical properties could significantly improve the design and testing pipeline for medical devices, the medical devices that are deployed in vivo

Summary

Introduction

Mitral valve diseases are among the most prevalent heart diseases, and their prevalence increases with age.[16]. Pre-procedural planning of procedures such as transcatheter mitral valve repair (TMVR) is primarily based on digital anatomic models created from clinical imaging data. When a nitinol TMVR (see Fig. 1a) device is deployed within a native mitral valve there are several deformation events that are expected: (i) the native mitral annulus is forced into a more circular configuration by the device; and the fully expanded device is compressed by the native annulus This is an important aspect of device sizing since anchoring of the device often requires a 10–15% oversizing against the native annulus, creating consistent radial tension by the nitinol frame.

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