Exercise induced irregular wide QRS tachycardia with right bundle branch block morphology and extreme QRS axis deviation

Abstract

A 29-year-old active woman was referred for evaluation following the development of an irregular wide complex tachycardia with right bundle branch morphology and extreme QRS axis during exercise stress testing. Two main alternative diagnoses are discussed: a) atrial fibrillation with either aberrancy or pre-excitation; b) left ventricular tachycardia originating from the Purkinje system including left posterior fascicle versus posteromedial papillary muscle.