Echocardiographic Assessment of Fetal Cardiac Function

Abstract

Advances in fetal cardiac echocardiographic imaging have enabled the evaluation of the fetal heart beyond its morphology and structure. Assessment of fetal cardiac function constitutes an important element of fetal echocardiography, given that intrinsic fetal myocardial abnormalities, structural congenital cardiac malformation, cardiac arrhythmias, and altered loading conditions in utero may lead to fetal myocardial dysfunction. Over the past two decades, non-invasive echocardiographic assessment of fetal cardiac function has continued to evolve for better definition of systolic and diastolic ventricular function in utero. These techniques include conventional two-dimensional echocardiography and Doppler interrogation of systemic venous and ductus venosus flow and estimation of cardiac output. New techniques include the use of three- and four- dimensional ultrasound for derivation of ventricular volumes and ejection fraction, tissue Doppler imaging, and strain and strain rate imaging. While postnatal echocardiographic parameters have been adopted for prenatal use, several intrinsic characteristics of the fetal heart and the available imaging modalities pose important challenges to their accurate derivation. These include the variable positioning of the fetus, smallness of the fetal heart, a fast heart rate, the lack of electrocardiographic monitoring, the need for standardization based on normal ranges in different phases of pregnancy, and the absence of validation for some of the indices. Despite these limitations, cardiac function can in the present era be more objectively assessed. Compilation of the different parameters into a cardiovascular profile has been used for serial assessment of the cardiac function to diagnose, monitor, and predict outcomes in selected fetal conditions. There was no doubt, however, that further validation studies are required for the new research echocardiographic modalities and that successful translation of these novel tools is eagerly awaited.