An electrophysiologic study of swallowing-induced tachycardia.

Electrophysiologic studies were performed on a 73-year-old man with swallowing-induced supraventricular tachycardia, in order to define the characteristics of this unique dysrhythmia in this patient. Swallowing reliably provoked an automatic atrial focus type of atrial tachycardia, which usually changed into an atrioventricular nodal reentrant tachycardia when a critical delay in atrioventricular nodal conduction (atrio-His interval greater than or equal to 340 msec) was achieved. The atrioventricular nodal reentrant form of tachycardia did not occur spontaneously. The ease of induction and the duration of the episodes of supraventricular tachycardia were facilitated with the intravenous administration of atropine and ouabain and were decreased with administration of procainamide hydrochloride.