Shortening of retrograde conduction time over slow pathway after atrial stimulation.

Abstract

A 44-year-old woman presenting with a history of multiple episodes of paroxysmal supraventricular tachycardia underwent electrophysiological studies and a catheter ablation procedure. The 12-lead electrocardiogram during sinus rhythm was normal. At baseline, dual atrioventricular (AV) nodal conduction was elicited by atrial extrastimulation and, during ventricular stimulation, decremental ventriculoatrial (VA) conduction was observed, with the site of earliest retrograde atrial activation visible near the ostium of the coronary sinus (CS).