CRISTAL TACHYCARDIAS - ORIGIN OF RIGHT ATRIAL TACHYCARDIAS FROM THE CRISTA TERMINALIS IDENTIFIED BY INTRACARDIAC ECHOCARDIOGRAPHY

Objectives. We sought to use intracardiac echocardiography (ICE) to id entify the anatomic origin of focal right atrial tachycardias and to d efine their relation with the crista terminalis (CT). Background. Prev ious studies using ICE during mapping of atrial flutter and inappropri ate sinus tachycardia have demonstrated an important relation between endocardial anatomy and electrophysiologic events. Recent studies have suggested that right atrial tachycardias may also have a characterist ic anatomic distribution. Methods. Twenty-three consecutive patients w ith 27 right atrial tachycardias were included in the study. ICE was u sed to facilitate activation mapping in relation to endocardial struct ures. A 20-pole catheter was positioned along the CT under ICE guidanc e, ICE was also used to assist in guiding detailed mapping with the ab lation catheter in the right atrium. Results. Of 27 focal right atrial tachycardias, 18 (67%, 95% confidence interval [CI] 46% to 83%) were on the CT (2 high medial, 8 high lateral, 6 mid and 2 low). ICE identi fied the location of the tip of the ablation catheter in immediate rel ation to the CT in all 18 cases. The 20-pole mapping catheter together with echocardiographic visualization of the CT provided a guide to th e site of tachycardia origin along this structure. Radiofrequency abla tion was successful in 26 (96%) of 27 (95% CI 81% to 100%) right atria l tachycardias. Conclusions. This study demonstrates that approximatel y two thirds of focal right atrial tachycardias occurring in the absen ce of structural heart disease will arise along the CT, Recognition of this common distribution may potentially facilitate mapping and ablat ion of these tachycardias. (C) 1998 by the American College of Cardiol ogy.