Repetitive monomorphic VT can arise from the outflow tract of either the right or left ventricle. The usual site of origin is the right ventricular outflow tract and the predominant morphology is a left bundle branch block with an inferior axis in the frontal plane. Rates of tachycardia are variable as are the effects from exercise, resulting in either suppression or enhancement of the arrhythmia. Isoproterenol, with or without programmed stimulation, facilitates the emergence of the arrhythmia in the electrophysiology lab. Presenting symptoms include palpitations, near-syncope, or occasionally complete syncope.
Sudden death is rare.
A differential diagnosis to be considered when evaluating patients with right ventricular outflow tract tachycardia is arrhythmogenic right ventricular dysplasia which occurs in the presence of a diseased right ventricle. The right ventricle is dilated and covered by fatty tissue and the musculature of the right ventricle is replaced with fatty infiltration and fibrous tissue. Most patients experience arrhythmias before the fourth decade of life. A history of exercise-related tachycardia is common in arrhythmogenic right ventricle dysplasia. Sudden cardiac death is associated with exertion in this syndrome.