Approach to the diagnosis and initial management of the stable adult patient with a wide complex tachycardia.

The initial electrocardiographic evaluation of every tachyarrhythmia should begin by addressing the question of whether the QRS complex is wide or narrow. The most important cause of wide complex tachycardia (WCT) is ventricular tachycardia. However, supraventricular tachycardia can also manifest with a wide QRS complex. The ability to differentiate between supraventricular tachycardia with a wide QRS due to aberrancy or preexcitation and ventricular tachycardia often presents a diagnostic challenge. The identification of whether WCT has a ventricular or supraventricular origin is critical because the treatment for each is different, and improper therapy may have potentially lethal consequences. In conclusion, although the diagnosis and treatment of sustained WCT often arise in emergency situations, this report focuses on a stepwise approach to the management of WCT in relatively stable adult patients, particularly the diagnosis and differentiation of ventricular tachycardia from supraventricular tachycardia with a wide QRS complex on standard 12-lead electrocardiography.