Patients with ascending aortic aneurysms are mostly young and middle-aged and often have an enlarged aortic sinus and annulus. In severe enlargement, the aortic valve leaflets fail to close together during cardiac diastole, presenting with incomplete aortic valve closure. However, the aortic valve leaflets themselves do not have significant pathology. Some patients may show signs of Marfan syndrome such as long head, high arched palate, elongated trunk, limbs, and fingers, hyperextended joints, pectus excavatum or funnel chest deformity, and congenital ocular crystal dislocation. Aneurysms of the ascending aorta that do not invade the aortic valve annulus may have no clinical symptoms in the early stages. If the aneurysm grows to compress the superior vena cava or the innominate vein, the veins in the neck and upper extremities may become angry and enlarge. In advanced cases, the aneurysm grows into the anterior chest wall and encroaches on the sternum, resulting in severe pain or even penetration of the chest wall and a pulsating mass. If the aneurysm leads to enlargement of the aortic valve annulus and incomplete closure of the aortic valve, clinical symptoms of congestive heart failure may occur. Physical examination may reveal diastolic murmurs, increased pulse pressure, and hydrophobic pulses associated with aortic valve insufficiency. Chest radiographs show enlargement of the ascending aorta and left ventricle. Electrocardiograms often show left ventricular hypertrophy and strain. Aortogram shows enlargement of the ascending aorta and aortic sinus. In ascending aortic aneurysms due to mesangial cystic degeneration, the lesion is mostly confined to the ascending aorta and the aortic external diameter is near normal from the origin of the innominate artery down. In cases with aortic valve insufficiency, the contrast agent regurgitates into the left ventricle during diastole, and the severity of aortic valve insufficiency can be determined by the amount of contrast agent regurgitation. 1. X-ray plain film examination: it can show the calcified aneurysm wall. 2. Arteriography: to clarify the site, scope and size of the aneurysm, which can help to make a clear diagnosis and formulate a surgical plan. 3. Ultrasonography: It can determine the size, pulsation and murmur of the aneurysm. 4. Reactive congestion test: to observe whether the lateral branch circulation of the affected limb has been adequately established. Thoracic aortic aneurysms can usually be seen on X-ray chest radiographs. CT and MRI are particularly helpful in confirming their extent and size. Transthoracic ultrasound can accurately measure the size of ascending aortic aneurysms but not descending aortas, and transesophageal ultrasound can accurately measure both. Aortic contrast angiography or magnetic resonance aortography is mostly indicated before thoracic aortic aneurysm preparation for resection. For syphilitic aneurysms, serum tests, especially the fluorescent dense spirochete antibody adsorption test and the pale dense spirochete (syphilis spirochete) immunoassay, are mostly positive. 5. Treatment: After the diagnosis is clear, surgical treatment should be performed as soon as possible. In cases without aortic valve insufficiency, surgical treatment should also be considered to prevent aneurysm rupture or complications of coarctation aneurysm. The majority of ascending aortic aneurysms are spindle aneurysms. The principle of treatment is to remove the diseased segment of the ascending aorta and replace it with an artificial vessel or homologous aorta. Since the procedure requires blocking the blood flow in the ascending aorta, care should be taken to protect the heart, brain, spinal cord and internal organs from ischemia and hypoxia, and the left ventricle from acute enlargement and failure due to blocked blood drainage. In cases of ascending aortic aneurysm with aortic valve insufficiency, aortic valve replacement, aneurysm resection and artificial vessel grafting are often required after removal of the aneurysm and aortic valve. 6. Prognosis: The surgical mortality rate for surgical treatment of ascending aortic aneurysms has been reduced to 5%-10%. Early mortality is higher in cases of aneurysms due to syphilitic aortitis and in cases complicated by coarctation aneurysms. Postoperatively, 90% of surviving cases have disappeared or significantly reduced symptoms, and cardiac function has returned to class I-II.