Bronchogenic cyst causing atrial fibrillation by impinging the right inferior pulmonary vein.

Atrial fibrillation is the most common sustained cardiac arrhythmia and is usually associated with underlying structural heart disease, but may also occur in isolation--the entity of "lone" atrial fibrillation. Recently, attention has been directed to the pulmonary veins as a source of the arrhythmia through identification of rapidly firing ectopic foci within the covering myocardial sleeves. We describe a 38-year-old man who presented with treatment-resistant atrial fibrillation and a posterior mediastinal mass. Electrophysiological studies demonstrated abnormal foci of electrical activity at the entrance of the right inferior pulmonary vein into the left atrium. Surgical exploration revealed a bronchogenic cyst that distorted and stretched the right inferior pulmonary vein as it traversed the posterior mediastinum towards the left atrium. Restoration of sinus rhythm without recurrence of atrial fibrillation characterized the clinical course after surgical resection of the mass. This case demonstrates that a retro-cardiac bronchogenic cyst can cause atrial fibrillation by impinging on a pulmonary vein.