1:1 atrioventricular conduction in congenital complete heart block.

A female neonate with congenital complete heart block developed atrioventricular conduction through an accessory pathway. Despite sinus rhythm and an adequate heart rate she developed severe dilated cardiomyopathy and died at age 14 months. This case illustrates that underlying heart block can be present in individuals with asymptomatic Wolff-Parkinson-White syndrome and that the dilated cardiomyopathy that occasionally accompanies autoimmune congenital heart block is not primarily caused by bradycardia.