Splitting: S1

The technique involves delivering two closely coupled premature stimuli (S1–S2 and S1–S2–S3) while observing changes in the His bundle electrogram (HBE) recorded from a His catheter. The primary goal of splitting S1 is to identify dual AV nodal physiology and to localize the site of conduction delay or block during programmed stimulation. It answers the clinical question: Is the delay in AV conduction due to the AV node or the His-Purkinje system?

Introduction In cardiac electrophysiology studies (EPS), S1 refers to a programmed electrical stimulus (a "drive train") delivered by a catheter positioned inside the heart, usually in the right atrium or right ventricle. Splitting S1 is a pacing maneuver used to assess the refractory periods of the atrioventricular conduction system—specifically, to differentiate between conduction delays occurring in the AV node versus the His-Purkinje system . splitting s1

This technique remains a valuable tool in the invasive cardiac electrophysiologist’s armamentarium for precisely localizing conduction abnormalities and guiding therapy. Introduction In cardiac electrophysiology studies (EPS)