A unique and complex pattern of intraventricular trifascicular block was documented electrocardiographically, for the first time, in a newborn infant with a history of transient intrauterine bradycardia. The clinical course was progressive, leading to a high-degree atrioventricular block, accompanied by severe Adams-Stokes attacks and congestive heart failure. Pacemaker therapy had to be instituted at the age of 3 months. Congenital intraventricular trifascicular block differs from the usual form of congenital heart block. It deserves close observation and early therapeutic intervention.
Chan T, Potter RT, Liu L. Congenital Intraventricular Trifascicular Block. Am J Dis Child. 1973;125(1):82-87. doi:10.1001/archpedi.1973.04160010052012