In Vitro Mitral Valve Model with Unrestricted Ventricular Access: Using Vacuum to Close the Valve and Enable Static Trans-Mitral Pressure

Figures

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  Fig. 1. Schematic representation of the left heart in vitro system, showing a side view (left) and isometric view (right) of the left heart model. Important components: (i) ventricular/atrial orifice, (ii) vacuum system input, (iii) vacuum gauge input, (iv) vacuum release valve, and (v) drain valve. Also shown is the testing system immediately before use of the vacuum system (b) and after valve closure (c). The white space inside the testing chamber represents the atrial-chamber airspace while the blue area represents water

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  Fig. 2. Valve mounting hardware and the scaffold shown in a exploded view and b and c with the scaffold mounted to the left heart model system. The scaffold positions the annulus clamp and PM orientation eyelets relative to each other and allows for attachment to the system. Green arrow denotes location of force transmission line tethering the papillary muscles through several orientation eyelets upwards to a pair of digital scales, fitted to measure PM force with 0.01N accuracy. APM and PPM: anterolateral and posteromedial papillary muscles, respectively

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  Fig. 3. Flowchart representation of vacuum system operation during testing procedure

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  Fig. 4. Atrial view of a mitral valve during a closure test. With the testing chamber elevated, still images were taken displaying the valve through the atrial chamber. The anterior leaflet (A) and regions of the posterior leaflet (P1, P2, and P3) are labeled and the coaptation line is marked with the dotted black line. a valve fully closed, the anterior leaflet can be seen covering most of the orifice; b after releasing the vacuum, the valve re-opened as the pressure difference was eliminated. The characteristic “D-shape” of the mitral valve annulus outline is denoted by the dotted red line of the closed valve

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  Fig. 5. Individual and total papillary muscle force as a function of trans-mitral pressure difference. Green line denotes physiological trans-mitral pressure of 120 mmHg

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  Fig. 6. Custom built full Wheatstone bridge based chordal force transducer on secondary strut chord