Electrical connection between the right atrium and the superior vena cava, and the extent of myocardial sleeve in a patient with atrial fibrillation originating from the superior vena cava.

We describe a case in which the superior vena cava (SVC) was electrically isolated by an application of radiofrequency energy to a point with electrical connection between the right atrium and the SVC in a patient with atrial fibrillation (AF) originating from the SVC. The connection was located in the posteroseptal region between the right atrium and the myocardial sleeve extending into the SVC. Local AF occurred after radiofrequency ablation and rapid activities were recorded all around the SVC, whereas the atrium was still in sinus rhythm. It is suggested that focal AF in the SVC contributes not only to the initiation but also to the maintenance of AF, and the myocardial sleeve extends into the SVC through a connection point to cover the entire internal lumen.