Accuracy of echocardiography measurements in the fetal lamb.

Echocardiography is becoming an important noninvasive method to evaluate the heart of the human fetus. Validation of this technique, however, is lacking. To establish the correlation of M-mode and two-dimensional echocardiography with direct invasive methods, the size and volume of the heart of 10 fetal lambs were determined. Both M-mode echocardiography as well as the two-dimensional method were found to correlate well with direct measurements. As determined by all three modalities, the right ventricular cavity was found to be larger than the left ventricular cavity. Intraventricular septum thickness was best measured by the two-dimensional technique, whereas posterior wall dimensions were difficult to assess by this technique. This is the first study that attempts to validate echocardiography as it pertains to the fetus. It shows that a good correlation between invasive and noninvasive methodology can be obtained. Encouraging findings may lead other investigators to use such techniques in the human fetus to quantify ventricular size and output under normal and abnormal conditions.