The aorta is the main blood vessel in the human body. As blood is pumped from the heart, it passes across the aortic valve, and then through the aorta, where it is then distributed through a system of smaller arteries. As the aorta travels through the body, each portion has a different name based on its location and each section supplies different organ systems or areas of the body. The aorta first leaves the heart and brings blood towards the head as the ascending aorta. As the aorta turns towards the left side of the body, it gives off branches to the upper body and the brain as the aortic arch. The aorta next travels down the chest, where it is called the descending aorta. The descending aorta continues through the abdomen as the abdominal aorta, where it supplies the abdominal organs before dividing to provide arteries for each leg (the iliac arteries).

The wall of the aorta is made up of three layers, the thin adventitia on the outside, the media, which is thicker and more elastic, and the delicate intima on the inside. The elastic nature of the vessel wall helps the aorta respond to the high pressures produced as blood is ejected from the heart.

Aortic Pathology
An aneurysm is a localized dilatation of a blood vessel. Aneurysms may occur in any artery in the body, and in the aorta they may occur in any segment, whether in the chest (the ascending aorta, the aortic arch, or the descending aorta) or in the abdomen (the abdominal aorta). In a true aneurysm, the dilation involves all the walls of the aorta, in contrast to a pseudoaneurysm, or “false” aneurysm. In a pseudoaneurysm, the dilation does not involve all the layers of the aortic wall, but instead is usually contained by only the thin layer of adventitia.



Diagnosis
There are many ways that doctors diagnose and follow aortic aneurysms. These different tests help to identify the presence of aneurysm as well as help determine treatment plans and follow up.

Chest x-ray: Often chest x-rays may suggest the presence of an aortic aneurysm. While they are not definitive studies, they may alert doctors of aortic pathology and suggest further tests.




CT scan: CT scan of the chest (often referred to as “CAT Scan”) is the preferred means of imaging aortic aneurysms, both at initial presentation and during follow-up. CT scans that focus on the aorta do require intravenous contrast, which may be contraindicated in some patients with allergies or kidney problems.




Echocardiography: Echocardiograms, whether transthoracic or transesophageal, may also help to provide further information about the aorta. Echocardiograms are of particular use when evaluating the ascending aorta, aortic valve and the heart.

MRI: Magnetic resonance imaging (MRI) is another useful tool for examining the aorta. The images obtained are similar to those provided by CT, but the intravenous contrast used is better tolerated by patients.