Differential diagnosis of regular, narrow-QRS tachycardias.

We present an update on clinical and electrophysiological criteria used for the differential diagnosis of regular supraventricular tachycardias. Although several electrocardiographic clues may assist in the differential diagnosis, this is usually accomplished at electrophysiology study, and most often, the differential diagnosis is between atrioventricular nodal reentrant tachycardia, atrioventricular reentrant tachycardia due to a concealed accessory pathway, and atrial tachycardia. Atrial and ventricular pacing maneuvers during sinus rhythm or tachycardia have been used with various success rates. In clinical practice, these techniques cannot be applied to all cases, and multiple criteria must be used for the differential diagnosis of narrow-complex tachycardias with atypical characteristics.