Abstract
A 64-year-old man with an atrial septal defect was referred for HotBalloon ablation of symptomatic drug-resistant paroxysmal atrial fibrillation. Pulmonary vein (PV) isolation was achieved using a SATAKE HotBalloon ablation system, which was inserted into the left atrium through the deflectable guiding sheath via the atrial septal defect. During ablation of the right superior pulmonary vein carina, the HotBalloon dropped to the left atrium. Hemoptysis and respiratory failure was then observed, and the patient was intubated and controlled under ventilator. The computed tomography identified a pseudoaneurysm developed on the right superior PV, with massive hemorrhagic alveolar flooding.