Wide QRS complex tachycardia: ECG differential diagnosis

Wide QRS complex tachycardias (WCT) present significant diagnostic and ther apeutic challenges to the emergency physician, WCT may represent a supraven tricular tachycardia with aberrant ventricular conduction; alternatively, s uch a rhythm presentation may be caused by ventricular tachycardia, Other c linical syndromes may also demonstrate WCT, such as tricyclic antidepressan t toxicity and hyperkalemia, Patient age and history may assist in rhythm d iagnosis, especially when coupled with electrocardiographic (ECG) evidence. Numerous ECG features have been suggested as potential clues to origin of the WCT, including ventricular rate, frontal axis, QRS complex width, and Q RS morphology, as well as the presence of other characteristics such as atr ioventricular dissociation and fusion/capture beats. Differentiation betwee n ventricular tachycardia and supraventricular tachycardia with aberrant co nduction frequently is difficult despite this clinical and electrocardiogra phic information, particularly in the early stages of evaluation with an un stable patient. When the rhythm diagnosis is in question, resuscitative the rapy should be directed toward ventricular tachycardia. Copyright (C) 1999 by W.B. Saunders Company.