Complicated atrial tachycardia due to atrial fibrillation originating from the superior vena cava

INTRODUCTION The superior vena cava (SVC) can act as an origin of atrial fibrillation (AF). The complex structure and special conductive properties of the SVC can result in complicated atrial tachycardia (AT), atrial flutter, or AF. SYMPTOMS AND CLINICAL FINDINGS We report a case of the clinical observation of various kinds of AT and AF in 1 patient. Electrophysiological (EP) studies confirmed the muscle sleeve in the SVC to be the primary trigger and the only site or origin of tachycardia in this patient. Furthermore, we describe the mechanism of AT observed in clinic, which was misdiagnosed as multiorigin AF. INTERVENTION AND OUTCOMES Circumferential pulmonary vein isolation and circumferential SVC isolation resulted in termination of tachycardia. CONCLUSION We present an atypical case of AF originating from the SVC with unusual intra-atrial conduction characteristics and arrhythmogenic pulmonary veins. Stepwise EP studies were conducive to clarify the mechanism of this rare AT.