[Provocation of the attack of supraventricular reciprocal paroxysmal tachycardia by frequent stimulation of the left atrium through the esophagus to determine its approximate range of reciprocal excitement].

The study involved 24 patients with supraventricular paroxysmal reciprocal tachycardia (SPRT) showing no ECG evidence of ventricular pre-excitation between the attacks. SPRT attacks could be provoked by frequent esophageal left-atrial stimulation in all patients, particularly with impulse frequencies in the 160 to 200 imp/min range, associated with first-degree atrioventricular block featuring Wenckebach's phenomenon. In most cases, induced SPRT was similar to a spontaneous attack. During an induced attack, the duration of Q--P interval was less than 70 ms in 15 (62.5%) suggesting that the scope of reciprocal excitation was limited to the atrioventricular node, and more than 70 ms in 9 (37.5%), indicating the involvement of complementary ventriculo-atrial pathways.