A novel left heart simulator for the multi-modality characterization of native mitral valve geometry and fluid mechanics

Numerical models of the mitral valve have been used to elucidate mitral valve function and mechanics. These models have evolved from simple two-dimensional approximations to complex three-dimensional fully coupled fluid structure interaction models. However, to date these models lack direct one-to-one experimental validation. As computational solvers vary considerably, experimental benchmark data are critically important to ensure model accuracy. In this study, a novel left heart simulator was designed specifically for the validation of numerical mitral valve models. Several distinct experimental techniques were collectively performed to resolve mitral valve geometry and hemodynamics. In particular, micro-computed tomography was used to obtain accurate and high-resolution (39 μm voxel) native valvular anatomy, which included the mitral leaflets, chordae tendinae, and papillary muscles. Three-dimensional echocardiography was used to obtain systolic leaflet geometry. Stereoscopic digital particle image velocimetry provided all three components of fluid velocity through the mitral valve, resolved every 25 ms in the cardiac cycle. A strong central filling jet (V ~ 0.6 m/s) was observed during peak systole with minimal out-of-plane velocities. In addition, physiologic hemodynamic boundary conditions were defined and all data were synchronously acquired through a central trigger. Finally, the simulator is a precisely controlled environment, in which flow conditions and geometry can be systematically prescribed and resultant valvular function and hemodynamics assessed. Thus, this work represents the first comprehensive database of high fidelity experimental data, critical for extensive validation of mitral valve fluid structure interaction simulations.

Cardiac axis-oriented full-volume data acquisition in real-time three-dimensional transesophageal echocardiography to facilitate on-cart analysis

We propose a useful method to acquire a full-volume dataset that allows for efficient assessment of cardiac structures by real-time 3-dimensional transesophageal echocardiography (3DTEE). In our method, bicommissural full-volume acquisition, the dataset is acquired with the X-Y-Z axes aligned along the lines connecting the mitral commissures, the mitral annular center to the left ventricular apex, and the mitral anterior-posterior ends, respectively. The image dataset obtained using this method not only allows for visualization of en face images of the cardiac structures, but box cropping of the dataset also provides useful sectional images that are the analogues of the standard 2DTEE views. Our method can potentially standardize 3D image orientation of the cardiac structures and facilitate intraoperative on-cart analysis in real-time 3DTEE.