Congenital heart block and cardiac anomalies in the absence of maternal connective tissue disease

The association of congenital heart block with maternal connective tissue disease and autoimmunity has been recently reported. Two cases of heart block were diagnosed in utero at 23 and 24 weeks' gestation. Both mothers had extensive workups for connective tissue disease that were negative. Two-dimensional and Doppler echocardiograpy were performed in utero and both infants had left atrial isomerism, atripventricular canal, defects, and severe hydrops in addition to heart block. Review of the recent literature identifies a 'subset of congenital heart block in which the mothers have no evidence for connective tissue disease, and the fetus or neonate has complex cardiac malformations and hydrops. The common features in these babies are atrioventricular canal defects and isomerism. No reports of congenital heart disease among the children of mothers with connective tissue disease fit this description. Our recent experience and literature review emphasize the previously known association between congenital heart block and congenital heart disease. This association is especially important in light of the poor prognosis for this group of fetuses and neonates.