Recurrent preexcited reciprocating tachycardia, concealed ventricular preexcitation and conduction disturbances in the normal atrioventricular pathway in a newborn.

We describe a newborn infant with concealed ventricular preexcitation in sinus rhythm on the early ECGs, and who developed recurrent episodes of preexcited reciprocating tachycardia. Manifestation of the ventricular preexcitation and initiation of the tachycardias were dependent on the presence of severe conduction disturbances in the normal atrioventricular pathway, probably in the atrioventricular node.