[Two-dimensional and Doppler echocardiographic evaluation of intrauterine blood flow dynamics in the fetuses with a ventricular septal defect].

In nine fetuses with ventricular septal defect (VSD), intracardiac blood flow was observed with color Doppler ultrasound. Interventricular shunt velocity, maximum systolic velocity in the ascending aorta and pulmonary artery, trans-atrioventricular blood flow velocity, and the flow pattern in the inferior vena cava were also measured with pulsed Doppler ultrasound. The cardio-thoracic ratio and ejection fraction were measured by B- and M-mood ultrasound. In all four fetuses with isolated VSD a bidirectional shunt was demonstrated. In the three normal developed fetuses time analysis showed a right (RT)-to-left (LT) shunt during systole and a LT-to-RT during diastole with maximum systolic velocities of 61cm/s, 42cm/s and 68cm/s. In the five fetuses with complexed cardiac malformation, two fetuses had a unidirectional shunt and three fetuses had a bidirectional shunt, which was a LT-to-RT during systole and a RT-to-LT during diastole. These studies indicate that although the systolic pressure in the right ventricle is slightly higher than that in the left, the pressure is almost the same in both ventricles. The presence of unidirectional shunting or a different time relationship from that of normal fetuses in bidirectional shunting would necessitate a careful check for other cardiac malformations.