Atrioventricular nodal reentrant tachycardia.

This entity represents the most common type of recurrent, regular, narrow QRS tachycardia in the absence of preexcitation syndrome. Electrophysiologic basis for the arrhythmia is reentry within the AV node resulting from dissociation between intranodal pathways. A better understanding of these intranodal pathways helps in the selection of a rational approach to management of these cases.