Population-Averaged Geometric Model of Mitral Valve From Patient-Specific Imaging Data

The mitral valve (MV) is one of the atrioventricular heart valves and regulates the blood flow between the left atrium and ventricle during the cardiac cycle. Its anatomical structure is comprised of anterior and posterior leaflets, chordae tendineae, and papillary muscles. The main function of the MV is to prevent blood flow regurgitation back into the left atrium during systole. Abnormalities in geometry of MV can lead to mitral insufficiency disorder, which requires either valve replacement or surgical repair to restore proper MV coaptation. Annually, over 40,000 patients in the U.S. alone are treated for MV disorders [1]. In the past two decades, the emphasis in MV treatment has been shifting from replacement toward repair due to lower morbidity and mortality of the latter approach [2]. However, the natural anatomical variability of human MV geometry precludes the use of single or simplified geometries for the simulation of surgical repair. One of the ways to address this issue is by using patient-specific diagnosis and modeling [3], or population-averaged geometric models of MV. The existing approaches for characterization and reconstruction of the cardiovascular organ-level geometry include fitting of predefined sets of nonuniform rational B-splines (NURBS) to the imaging data [4], and using spheroidal harmonics representations [5]. Even though it is possible to construct average geometric models this way, the analysis of anatomical shape variations becomes difficult in this setting because of the confounding of dimensional and shape descriptors. At the same time, none of the existing methods allow integration of the high-fidelity in vitro data with lower-resolution in vivo imaging in a consistent manner. In this work, we formulate the framework for building the population-averaged geometric model of MV, which lends to straightforward analysis of dimensional and anatomical variations. In the sections to follow, we discuss the procedure and advantages of this method for the development of robust medical devices and treatment procedures.