Cardiac ultrasound AAOD is a letter abbreviation describing the diameter of the ascending aorta, which can be used to express whether the ascending aorta is at a normal diameter size, widened or narrowed. Cardiac ultrasound AAOD refers to the internal diameter of the ascending aorta, and the width of the ascending aorta is 25 to 30 mm. If it is less than 25 mm, it represents stenosis of the ascending aorta, which can be seen in ascending aortic plaque formation, tumors, and so on. If it is greater than 35mm, it represents widening of the ascending aorta, which can be seen in physiologic changes. If the widening is greater than 40mm, it belongs to pathological changes, which can be seen in hypertension, obesity, coronary heart disease and so on. Cardiac ultrasound is used to check for congenital heart disease, heart valve disease, pericardial effusion, etc. It is a non-invasive examination. It is a non-invasive examination, and once abnormalities are found, it should be promptly consulted and standardized under the evaluation of professional doctors.