Dressler's Beat

A Dressler beat (a.k.a. fusion beat) occurs during ventricular tachycardia and is also known as a fusion beat.

This occurs when sinus node activity (P wave) begins to conduct through the normal conduction pathway during an episode of ventricular tachycardia. The abnormal ventricular impulse then conducts retrograde across the AV node and the resulting QRS is a “fusion beat” of the normal QRS morphology and that of the ventricular morphology from the ventricular tachycardia.