Fig. 1

Computed tomography image showing the right atrial appendage aneurysm and an intraluminal filling defect. Axial computed tomography image (2.5 mm slice thickness) obtained after administration of intravenous iodinated contrast in soft tissue window centered at the level of the heart. There is aneurysmal dilatation of the right atrial appendage causing marked mass effect on the right ventricle, deforming its free wall (arrow). Note the 7.6 × 3 cm area of hypoenhancement/filling defect (asterisk) at the tip of the right atrial appendage, which could be the result of either slow flow with poor mixing of contrast or thrombus formation. Notice the layering of the iodinated contrast in the dependant portion of the right atrial appendage, more consistent with slow flow and poor mixing of contrast (arrowhead). The right coronary artery and acute marginal branch with surrounding epicardial fat are seen in the atrioventricular groove. A, RAA aneurysm; O, ostium of RAA; LV, left ventricle; RV, right ventricle; RCA, right coronary artery; AMB, acute marginal branch