Numerical assessment of the anatomy of the annulus fibrosus of the mitral valve in health and disease as per three-dimensional echocardiography

Aim. We analysed the geometry and dynamics of the annulus fibrosus of the mitral valve in normal conditions, with mitral regurgitation of degenerative and ischaemic aetiology based on three-dimensional echocardiography with subsequent mathematical processing. Methods. We included the data of transesophageal three-dimensional echocardiography of 50 patients in the following three groups: 10 patients with degenerative regurgitation, 10 patients with ischaemic mitral regurgitation and 30 patients in the 'normal' group without mitral valve pathology. Transesophageal echocardiography was performed using an iE33 expert level equipment (Philips, USA), to quantitatively analyse the anterior-posterior diameter, anterolateral-posterior median diameter, intercommissural diameter, three-dimensional circumference of mitral valve, two-dimensional height of the coaptation zone, leaf height, maximum height, front and back angles of the valves, nonplanar angle, planarity coefficient and ellipticity coefficient. The measurements were performed for both the phases of the cardiac cycle, the period of expulsion of systole and the period of diastole filling, corresponding to the closed and open states of the valve. In addition, the treated data sets were processed in the QLAB programme (Philips, USA) where sets of points describing the geometry of the mitral valve were obtained. Thereafter, we used the in-house algorithm in the MATLAB R2015a environment (MathWorks, Massachusetts, USA). Mathematical models of the anatomy of the annulus rings were obtained for all the three studied groups. Results. A functional study of the mitral valve showed a similar nature of changes in the geometric features of the annulus fibrosus for both the pathologies. The dynamic performance of the fibrous rings during systole-diastole cycle significantly differed among the studied groups. We present the equations for the averaged models of the annulus fibrosus of the groups analysed in the study that can be used in design, verification and computer modelling problems. Conclusion. Pathological changes in the geometry of the mitral valve during ischaemic and degenerative regurgitation work on a similar principle, although there are aetiological differences. However, these pathologies differ when the changes in the geometry of the dynamics of'systole-diastole' are analysed that warrant the use of different approaches and devices for their correction.