Retrograde (ventriculoatrial) conduction in congenital complete heart block.

Retrograde ventriculoatrial (VA) conduction is documented at the time of dual chamber pacemaker implantation in a 36-year-old patient with congenital complete atrioventricular (AV) block. Programmed ventricular stimulation with stimuli of increasing prematurity demonstrated a lack of decremental conduction via a unidirectional retrograde pathway. Because retrograde VA conduction has been associated with pacemaker mediated endless loop tachycardia, the status of retrograde conduction should be assessed in all patients undergoing dual chamber pacemaker implantation, including those with congenital complete AV block who have previously been considered to have no conductive tissue between atria and ventricles.