Abstract. The aim of the present study was to explore the clinical value of prenatal echocardiographic examination in the diagnosis of fetal cardiac tumors. In total, the cases of 8 fetuses with fetal cardiac tumors, which were identified by prenatal ultrasound examination in The First Affiliated Hospital of Nanchang University between January 2012 and January 2014, were retrospectively analyzed. The size, shape, location, activity and hemodynamic changes of the lesions were described in detail, and the patients were followed up. Out of the 8 identified cases of fetal cardiac tumors, 2 fetuses contained tumors only in the left ventricular cavity and 6 fetuses contained tumors of the left and right ventricular cavities, interventricular septum and apex of the heart. Overall, 5 of the 8 female patients requested termination of the pregnancy and labor was induced. The fetuses were pathologically confirmed to possess rhabdomyoma. In addition, 1 patient was followed-up for 5 weeks, and the tumor in the fetal heart cavity was found to have enlarged and developed in multiple regions when follow-up was performed. The patient then requested termination of the pregnancy and labor was induced. The fetus was pathologically confirmed to possess rhabdomyoma. The remaining 2 patients insisted on continuation of the pregnancy and the fetuses were followed up during gestation and subsequent to birth by echocardiographic examination. Prenatal echocardiography may precisely position and diagnose occupying lesions of the fetal heart, which is of considerable value in clinical decision making and instruction for treatment.

Although rarely discussed, material modeling of the myxomatous leaflet is considered as the cornerstone of mitral valve finite element analysis. The present study presents an incompressible, hyperelastic constitutive model to characterize myxoid mitral leaflet tissue mechanics. The model incorporates the transversely isotropic response and the layered structure of the tissue. First, an analytical constitutive model for the tissue is developed based on continuum mechanics and layered composites theory. Second, the material constants of the constitutive equation are determined by fitting the model to the experimental data. The analytical material model is then implemented using solid finite element methods by simulating a biaxial tensile test. A numerical simulation of the out-of-plane pressure loading is also conducted. Both the analytical outcomes and the simulated results agree well with experimental data and show good mutual agreement. The calculated strain distribution of the out-of-plane pressure loading simulation indicates myxoid leaflets exhibit enhanced extensibility and decreased stiffness compared to normal valves; the radial direction is more extensible than the circumferential direction. The presented material approximation is able to capture the myxomatous mitral leaflet mechanics. The results of the numerical simulation conform to those of the experimental tests.

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Objectives: To investigate the influences caused by special morphologies and dynamics of the substructures of mitral valve by the explicit finite element program LS-DYNA. Methods: A new finite element model for the mitral apparatus characterized by layered structure of leaflets tissue, saddle shape and contraction of annulus, an approximately accurate morphology of chordae tendineae was developed. The coaptation length, leaflets stress and strain of the present model were compared with those of two auxiliary models, one with planar annulus and the other with fixed annulus. The tensile function and force distribution of chordae tendineae were analyzed in the models with and without chordae tendineae. Results: The stretch ratios computed by the present model were most closely to the experimental data. The leaflets instantly turned over to the atrial side and larger load was observed in the model without chordae tendineae. Besides, tensile force was highly correlated with average diameter of chordae tendineae (r = 0.965). Conclusion: The saddle shape of annulus benefits valve coaptation and the contraction of annulus could help decrease loads on leaflets and prevent stress concentrating excessively. Chordae tendineae could bear partial loads on the leaflets, and prevent the leaflets to turn over to the side of the atrium and help the valve close successfully.