Interesting Response with the Delivery of Right Ventricular Extrastimulus of Increasing Prematurity

A 45-year-old man with no structural heart disease underwent an electrophysiology study for recurrent episodes of palpitation. There was no evidence of pre-excitation on the baseline electrocardiogram. Baseline intervals, including the A–H and H–V intervals, were within the normal limits and remained so during the electrophysiology study. An interesting response was observed with the delivery of ventricular extrastimuli with increasing prematurity from the right ventricular apex, triggering consideration of the possible mechanism.