Ultrasonic assessment of cardiac function in the intact human fetus.

Echocardiography may provide information concerning the structural development of the fetal human heart. The information available from such studies, when interpreted in light of existing knowledge of developmental cardiac physiology, may give insight concerning in utero cardiac pump function. The quantitation of cardiac structural growth in utero has been used to provide growth curves for the chambers of the fetal heart. Disparity in the ratio of right ventricular/left ventricular size (normally 1.0 to 1.2) may suggest acute ventricular failure and dilation. Electromechanical analysis using M-mode techniques may be used to analyze and monitor the treatment of fetal cardiac arrhythmias and provide systolic time interval analysis. Doppler waveform analysis provides information concerning directional flow and vascular impedance and Doppler flowmetry has promise for the measurement of fetal aortic and umbilical venous blood flows. Such studies have increased our understanding of fetal circulatory function and have practical implications for the establishment of fetal cardiac diagnosis and treatment programs.