Fetal echocardiography--applications and limitations.

Fetal echocardiography has been a useful technique for demonstrating the anatomy of the developing human heart. M-mode echocardiography may be used to provide rhythm diagnosis in the absence of high-fidelity transabdominal fetal electrocardiograms. The information so generated may be applied to plan the management of pregnancy and delivery in a population at "high risk" for structural or functional heart disease and may provide the impetus for developing in utero treatment programs. For this reason, a high degree of sensitivity and specificity must be asked of the technique and of the personnel performing the examination. "Major" malformations which impart marked hemodynamic and structural alterations on the fetal heart may be reliably diagnosed. Diseases which must be identified on the basis of direct recognition of subtle abnormalities of structure, with little impact on fetal flow patterns (e.g. mild semilunar valve stenosis of perimembranous ventricular septal defect) have been more problematic. Before effective screening and treatment programs for the fetal heart can be developed, a cooperative effort between cardiologists and perinatologists is essential in order to gain facility with imaging as well as familiarity with the natural history of these conditions.