Use of P Wave Configuration During Atrial Tachycardia to Predict Site of Origin

Objectives. This study sought to construct an algorithm to differentiate l ft atrial from right atrial tachycardia foci on the basis of surface electrocardiograms (ECGs). Background. Atrial tachycardia is an uncommon form of su-praventricular tachycardia, often resistant to drug therapy. Methods. A total of 31 consecutive patients with atrial tachy-cardia due to either abnormal automaticity or triggered rhythm underwent detailed atrial endocardial mapping and successful radiofreqnency atheter ablation of a single atrial focus. P wave configuration was analyzed from 12-lead ECGs during tachycar-dia during either spontaneous or pharmacologically induced atrioventricular block. P waves inscribed above the isoelectric line (TP interval) were classified as positive, below as negative, above and below (or conversely, below and above) as biphasic and flat P waves as isoelectric (0). In 17 patients the tachycardia was locate