Acute right-sided heart failure due to hemorrhage into a pericardial cyst.

This is a description of a rare complication of a pericardial cyst with spontaneous internal hemorrhage and following tamponade. The noninvasive diagnosis was done by transesophageal echocardiography and computed thoracic tomography. The cyst was thoracoscopically removed and pathologically examined. This case demonstrates a rare but important and life-threatening complication of mostly asymptomatic pericardial cysts.