Coronary artery aneurysms are uncommon, but since the introduction of coronary angiography and more recently echocardiography, several cases have been reported in the In this report we describe the echocardiographic features of an unruptured giant aneurysm of the right coronary artery, which was proved and successfully excised at operation. REPORT ON PATIENTA 25-year-old woman had been well until three months before admission when she experienced palpitation, cough, shortness of breath, and at times dizziness. Peripheral edema was intermittently present. An echocardiographic study suggested a right ventricular mass. On physical examination, the patient appeared ill with purplish-red cheeks, slight icterus sclera, and mild engorgement of the jugular veins. Her blood pressure was 110/90 mmHg and her heart rate was regular at 105 beatdmin. On auscultation, S1 and S2 were normal, and a S4 was heard over the precardium. A grade II/VI systolic ejection murmur was present along the left sternal border. Mild cyanosis at the tip of the fingers without clubbing was noted. The liver was enlarged and there was mild edema of the lower extremities. The chest X-ray showed a slighly enlarged heart shadow with a cardiothoracic ratio of 0.55 and a slightly decreased pulmonary vascularity. The electrocardiogram showed sinus tachycardia, low QRS voltage, and a Q wave in V3-V6 in- 502dicating an old anteroseptal myocardial infarction. Parasternal long-axis two-dimensional echocardiography showed a large oval cystic mass measuring 8 x 12 cm. Cloud-like echoes moved turbulently in the cystic cavity while the cystic mass itself showed little motion. The left atrium and ventricle were very small. The motion of the mitral and aortic valves was difficult to visualize (Figure 1). In the apical four-chamber view, the right ventricle was very small and the cystic tumor was in front of it. In this view, the moving cloud-like echoes were also seen in the cystic cavity. The right atrium was markedly enlarged (Figure 2). At operation, a mass lesion suggestive of a coronary aneurysm was found in front of the right ventricle, almost obscuring the whole operative field. The inferior and superior vena cavae were engorged. The right atrium measured approximately 12 cm in diameter and the giant oval cystic lesion measured 13 cm X 15 cm. No blood vessels were found on its surface. Temporal occlusion of both the proximal and distal openings caused no EKG changes, which suggested there were adequate collaterals.Cardiopulmonary bypass was instituted and the cystic tumor decreased in size. It was founc! to be an aneurysm of the right coronary artery containing oxygenated blood arising from the proximal segment of the right coronary artery about 3 cm from its origin. The aneurysm measured 15 cm in diameter and its wall was about 4 mm in thickness. The aneurysmal wall was smooth and no mural thrombus was found. The proximal and distal openings of the aneurysm were about 0.5 cm and 0.2 cm in diameter, respectively. The aneurysm of the right coronary artery wa...