[Right retroauricular hematoma of late manifestation. Contribution of cardiac imaging]

Right intrapericardial retroatrial haematomas are usually discovered in an acute context of tamponade, following cardiac surgery. The original feature of this case was the asymptomatic nature of a right retroatrial haematoma, after surgical closure of an ostium secundum atrial septal defect, with a free interval of more than 20 years between the surgical procedure and the first relatively minor symptoms, consisting of supraventricular arrhythmias. It can be difficult to determine the intra- or extra-atrial topography of a right-sided mass by transthoracic echocardiography. On the other hand, transoesophageal echocardiography and ultrafast CT can provide a precise topographic diagnosis and appear to be complementary to assess the nature of pericardial masses.