A 55-year-old woman with non-ischemic cardiomyo- pathy presents with this wide complex tachycardia. ECG shows?

Ans. (a) Ventricular tachycardia.* This tracing reveals a wide complex tachycardia at a rate of approximately 150 beats/ min.* Most of the ventricular beats have identical morphologies; hence, this is a monomorphic wide complex tachycardia (in contrast to a polymorphic ventricular tachycardia where the majority of the QRS complexes have a varying morphology).* The differential diagnosis of a monomorphic wide complex tachycardia includes ventricular tachycardia or supraven -tricular tachycardia conducted with aberrancy. Several clues in this tracing suggest the diagnosis of ventricular tachycardia.* When ventricular tachycardia occurs, ventricular depolarization does not conduct through the normal His-Purkinje system but rather conducts slowly directly through ventricular myocardium. During some ventricular tachycardias, sinus node depolarization continues unabated, and most of the sinus impulses meet a refractory ventricle due to the dominant ectopic ventricular activity preventing conduction.