In Vitro Mitral Valve Simulator Mimics Systolic Valvular Function of Chronic Ischemic Mitral Regurgitation Ovine Model

Abstract

Background This study was undertaken to evaluate an in vitro mitral valve simulator's ability to mimic the systolic leaflet coaptation, regurgitation, and leaflet mechanics of a healthy and chronic ischemic mitral regurgitation (IMR) ovine model. Methods Mitral valve size and geometry of both healthy and chronic IMR ovine animals was used to recreate systolic mitral valve function in vitro. A2-P2 coaptation length, coaptation depth, tenting area, anterior leaflet strain, and mitral regurgitation were compared between the animal groups and valves simulated in the bench-top model. Results For the control conditions, no differences were observed between the healthy animals and simulator in coaptation length (p=.681), coaptation depth (p=.559), tenting area (p=.199), and anterior leaflet strain in the radial (p=.230) and circumferential (p=.364) directions. For the chronic IMR conditions, no differences were observed between the models in coaptation length (p=.596), coaptation depth (p=.621), tenting area (p=.879), and anterior leaflet strain in the radial (p=.151) and circumferential (p=.586) directions. Mitral regurgitation was similar between IMR models with an asymmetric jet originating from the tethered A3-P3 leaflets. Conclusion This study is the first to demonstrate the effectiveness of an in vitro simulator to emulate the systolic valvular function and mechanics of a healthy and chronic IMR ovine model. The in vitro IMR model provides the capability to recreate intermediary and exacerbated levels of annular and subvalvular distortion at which IMR repairs can be simulated. This system provides a realistic and controllable test platform for the development and evaluation of current and future IMR repairs.

Bench Models for Assessing the Mechanics of Mitral Valve Repair and Percutaneous Surgery

“…To date, published studies have primarily focused on functional diseases that include ischemic and non-ischemic dilated cardiomyopathies. 8,28,29,34,35,37,46,47 In functional disease, left ventricular remodeling distends the MV geometry by dilating the MV annulus and displacing the PMs away from the mitral leaflets. These geometric distortions restrict systolic leaflet motion, generate gaps between the closed leaflets, and lead to MR.…”

“…While the majority of annuluses reported in literature provide only a single size, adjustable and flexible annuluses have been reported. 22,29,37,46,47 These designs are described and evaluated in subsequent sections evaluating methods of assessing MV annuloplasty.…”

“…1a). 5,8,12,[18][19][20]22,23,[26][27][28][29][30][31][32][34][35][36][37][38][39]44,[46][47][48] These components are supplemented by systemic resistances and compliances to control cardiac output, systemic pressures, and dampen undesired flow and pressure oscillations within the rigid chambers of the system.…”

“…These models have been used to evaluate multiple repairs on a single MV, changes in leaflet mobility and coaptation, improvements in transmitral hemodynamics, and provide direct quantitative measures of tissue loading. [3][4][5]8,9,[11][12][13][14][17][18][19][20][22][23][24][26][27][28][29][30][31][32][33][34][35][36][37][38][39]41,42,44,[46][47][48] Within the limitation of each setup, these models are more risk averse, controlled, reproducible, and less expensive than clinical studies or large animal models. Understanding the advantages and limits of these models will aid the interpretation of their resulting data, inform future experimental evaluations, and further the translation of results to procedure and device development.…”

Multi-modal Pipeline for Comprehensive Validation of Mitral Valve Geometry and Functional Computational Models

“…A novel closed-loop left heart simulator ( Fig. 1) was utilized to carry out controlled in-vitro MV experiments [7,8]. It allows for precise control of annular and subvalvular MV geometry at physiological left heart hemodynamics.…”