Echocardiographic evaluation of the valves and roots of the pulmonary artery and aorta in the developing fetus.

Because of the fluid-filled lungs in the fetus, the ultrasound beam can penetrate to the root of the pulmonary artery perpendicularly. Using M-mode echocardiography, the following dimensions were measured: the pulmonary and aortic valve excursion in 19 fetuses, and the pulmonary and aortic root internal diameter in 70 fetuses, between 18 and 42 weeks, menstrual age. The measured dimensions were then correlated with the biparietal diameter. The correlation coefficients for the measurements ranged from 0.873 to 0.892. Regression analysis showed that the best fit of the data was a linear model from which the 5% and 95% confidence limits were derived for individual predictions of the arterial dimensions. The ratios of the pulmonary/aortic valve excursion and the pulmonary/aortic internal diameter were approximately 1:1. These results are of potential value in the prenatal detection of great arterial valve or root diseases.