Congenital complete heart block and maternal connective tissue disease.

Congenital complete heart block can be isolated or can occur in association with other structural heart diseases. Isolated congenital complete heart block (CCHB) is due to transplacental transfer of autoantibodies from mothers with connective tissue disease. Congenital heart block is usually complete, but incomplete blocks, sinus bradycardia and QTc prolongation are also reported. Anti SS A and Anti SS B antibodies transferred from mothers have inflammatory and arrhythmogenic effects in the fetal conduction system. Cardiac manifestations reported include dilated cardiomyopathy, endocardial fibroelastosis and mitral insufficiency. Low ventricular rate, QT prolongation and arrhythmias on monitoring are high risk features. CCHB has a mortality of 30%, and 60% of infants require pacemaker therapy. Fetal echocardiography is useful in early diagnosis. Prophylactic steroid therapy is controversial. Beta adrenergic agonists were tried in mothers with fetuses having congenital heart block to increase fetal heart rate. Early pacemaker therapy is indicated in patients with symptomatic bradycardia and ventricular dysfunction. The indications for pacing in congenital heart block continue to evolve with advances in techniques and most of these children will ultimately require permanent pacemakers by adulthood.