Reverse Wenckebach “pseudo-supernormal” conduction or paroxysmal atrioventricular block

Paroxysmal atrioventricular-block is a poorly-recognized cause of atrioventricular conduction abnormality leading to syncope and can be fatal. Here we report a case of paroxysmal atrioventricular-block presenting as syncope treated effectively with pacemaker implantation and review the current literature on prevalence, known mechanisms and treatment for it. Importantly we provide the diagnostically important differentiating points between vagally mediated block and paroxysmal atrioventricular-block as well as the highlight the vastly varying prognosis between the two.