Ultrasonic identification and examination of fetal heart structures.

Ultrasonic studies were performed on normal fetuses ranging from 36 to 40 weeks gestational age in an attempt to visualize anatomical details of the fetal heart. We were able to visualize cardiac structures hitherto thought to be unidentifiable. Two-dimensional B-scan exposures of sections showed transverse and longitudinal sections of the fetal heart, including the cardiac septa and inlet and outlet sites of the large vessels. To attempt to elucidate the dynamics of the fetal heart, the motility patterns of the cardiac structures were examined by time-motion mode scanning and the patterns obtained were compared to those observed in the postnatal heart. The reliability of the theories advanced and the further prospects are discussed.