Fetal cardiac asymmetry: A marker for congenital heart disease

Objective: To determine the sensitivity of prenatally detected fetal cardia c asymmetry as a sonographic marker for congenital heart disease. Methods: The normal ratios of pulmonary artery to aorta diameters and of ri ght ventricle to left ventricle diameters were derived from normal fetuses scanned at 17 weeks or more in a 65-month period. Cross-sectional diameters of cardiac ventricles and great arteries were measured at the level of the valves at the time of the scan. Fetuses with confirmed cardiac anomalies d etected prenatally during the study were examined to identify how many had cardiac asymmetry, determined by abnormal ratios. Results: Linear regression analysis of the group of 881 normal fetuses show ed the normal pulmonary artery to aorta diameter ratio remained constant th roughout pregnancy and the normal right ventricle to left ventricle ratio i ncreased slightly with progressing gestational age. The 90% confidence inte rvals were 0.79, 1.24 for the right ventricle to left ventricle ratio and 0 .84, 1.41 for the pulmonary artery to aorta ratio. Of the 73 fetuses with a bnormal hearts, 66% had either ventricular or great artery asymmetry (at le ast one of the two ratios was abnormal). However, if no asymmetry was prese nt, the cardiac defect was more likely to be a minor one. Conclusion: Cardiac asymmetry was present in two-thirds of fetuses with car diac anomalies diagnosed prenatally. If cardiac asymmetry is found, a more thorough examination of the fetal heart is indicated. (Obstet Gynecol 1999; 93:189-92. (C) 1999 by The American College of Obstetricians and Gynecologi sts.).