Abstract

Three patients with repetitive supraventricular paroxysmal tachycardia are described, one of them with an atrial septal defect in addition. All three patients were asymptomatic; two, however, had a striking cardiomegaly (one of these is the patient with atrial septal defect). The electrocardiogram showed supraven-tricular tachycardia of medium frequency as the predominant rhythm, interrupted by phases of normal sinus rhythm of varying duration. The P waves were present during tachycardia and suggested a left atrial pace-maker. This was confirmed by comparison of right and left atrial (or pulmonary arterial wedge, respectively) pressure curves during both normal sinus rhythm and supraventricular tachycardia. Parkinson and Papp (I947) defined the clinical and electrocardiographic criteria of repetitive paroxys-mal tachycardia. The ectopic pacemaker in this form of tachycardia may be located in the atria, in the atrioventricular junction, and in the ventricles. Chronicity, relatively slow frequency, and easy identification of P waves allow discrimination of the repetitive from the more usual form of supra-ventricular tachycardia. Within the past few years, we have seen 7 patients with supraventricular repetitive paroxysmal tachy-cardia whose electrocardiograms fulfilled the cri-teria for left atrial origin of the ectopic focus. In 3 of these patients, diagnostic heart catheterization was performed and confirmed the site of the ectopic pacemaker in the left atrium. Methods The electrocardiograms were registered by means of a Siemens Cardiorex 6 T recorder. Right and left atrial or pulmonary arterial wedge pressures were measured consecutively using Cournand catheters (No. 6 or 7 F) or simultaneously (Case 2) using a Courmand double lumen catheter. They were recorded together with one or several standard electrocardiogra-phic leads on a photographic recorder (Electronics for Medicine). Statham transducers P 23 Db were used as pressure transducers. Subjects The 3 patients were referred for diagnostic evaluation because of an irregular heart.