The Society of Cardiovascular Anesthesiologists and American Society of Echocardiography have defined six imaging planes to interrogate the thoracic aorta by transesophageal echocardiography (TEE):

In both long- and short-axis views, it is important to consider the aortic wall thickness and tissue characteristics, aortic dimensions, pathology, and blood flow patterns.

Epiaortic scanning may permit higher resolution imaging of TEE blind spots in the distal ascending aorta

The ascending aorta arises from the left ventricle posterior to the right ventricular infundibulum and the pulmonary valve. It courses superiorly and slightly rightward.

The aortic arch gives rise to the innominate (brachiocephalic artery), left common carotid artery, and left subclavian artery.

The descending thoracic aorta begins distal to the left subclavian artery at the level of the ligamentum arteriosum and courses caudally in the left thoracic cavity.

At the level of the distal portion, the descending thoracic aorta lies directly posterior to the esophagus.

Atherosclerosis of the ascending aorta and aortic arch is now recognized as one, if not the major, predictor of postoperative stroke after cardiac surgery. Echocardiography should be used to identify aortic atherosclerosis prior to anticipated instrumentation.

Epiaortic scanning should be performed in high risk patients to further delineate the sites of severe atherosclerosis so that surgical modifications can be made.

Identification of significant aortic atherosclerotic disease by echocardiography permits potential alterations in the surgical procedure, including femoral artery cannulation, change in the site for aortic cross-clamp, avoidance of aortic cross-clamp using fibrillatory or hypothermic arrest, alteration of the site of vein graft anastomoses, relocation of the cardioplegia needle, and avoidance of antegrade cardioplegia by using retrograde cardioplegia.

Echocardiography can be used to define the size, location, and extent of the aortic aneurysm as well as the presence of a hematoma or thrombus.

Echocardiography can also be useful to identify concurrent aortic valve disease and influence the decision regarding aortic valve repair versus replacement.

According to the DeBakey Aortic Dissection Classification system, a Type I dissection extends from the ascending aorta and arch to the descending aorta, while a Type II dissection is limited to the ascending aorta.

A Stanford Type A dissection involves the ascending aorta, regardless of the origin of the tear or the extent of dissection, and a Type B involves only the descending thoracic aorta. The therapeutic approach tends to be more conservative due to the generally lower mortality rate.

TEE permits an accurate diagnosis of the location and extent of the aortic aneurysm, aortic valve evaluation for aortic insufficiency, pericardial effusion, and evidence of left ventricular dysfunction.

Two-dimensional echocardiography and color flow Doppler can help to define the true and false lumens of the aortic dissection as well as any involvement of the coronary arteries.

Although MRI remains a more sensitive and specific test for diagnosing the presence of an aortic aneurysm, TEE is highly accurate, is noninvasive, permits real-time analysis, and can be performed efficiently at the bedside in critically ill patients.

Limitations of TEE include the potential for artifacts and difficulty in visualizing the distal ascending aorta due to the blind spot.