What is a large Thoracic Aortic Aneurysm

A thoracic aortic aneurysm is an abnormal widening to 4.5 centimeters or more of a portion of the aorta that resides within the chest cavity. Even 5.0 centimeters in the section of the aorta just after it leaves the heart would be considered large. The greater the diameter of the aneurysm, the higher the risk of rupture.