Entrainment of a wide QRS complex tachycardia with progressive atrial delay: What is the mechanism?

A 47-year-old woman underwent electrophysiological testing of a wide QRS complex tachycardia (WCT). At baseline, atrio-Hisian and His-ventricular intervals were normal. Neither atrial extrastimulation nor atrial burst pacing revealed any evidence of dual atrioventricular (AV) nodal physiology and apparent ventricular pre-excitation, and ventriculoatrial (VA) conduction appeared to be absent. Atrial extrastimulation induced a WCT exhibiting an eccentric atrial activation sequence (Figure-1A). During the WCT, ventricular overdrive pacing (VOP) from the right ventricular apex (RVA) resulted in the progressive prolongation of the atrial cycle length (CL) (Figure-1B).

Source: Heart Rhythm - June 10, 2020 Category: Cardiology Authors: Taihei Itoh, Masaomi Kimura, Kimitaka Nishizaki, Hirofumi Tomita Source Type: research