Multiple forms of atypical atrioventricular nodal reentrant tachycardia with different right- and left-sided retrograde slow pathways.

A 56-year-old man was admitted for the treatment of supraventricular tachycardia. After successful ablation of the left concealed accessory pathway, four fast-slow forms of atrioventricular nodal reentrant tachycardia associated with different right- and left-sided retrograde slow pathways were induced. The locations of retrograde slow pathway were observed at the left inferior paraseptum, left mid-septum, right inferior paraseptum, and coronary sinus ostium, respectively. These retrograde slow pathways formed the integral limb of each tachycardia because conduction block of each slow pathway by catheter ablation was associated with the termination of tachycardia or abrupt change in the atrial activation sequence.