It forms where the wall has weakened, often due to the build-up of plaque .
Ruptures are very painful events that cause massive internal bleeding.
The patient must be treated within minutes in order to have a chance of survival. If an aneurysm bursts in the chest, there is only a 20 percent chance of survival. Therefore, early diagnosis and treatment are critical. The aorta is the main artery carrying oxygen-rich blood from the heart to the rest of the body. Typically, the widened part of the aorta is considered to be an aneurysm when it is more than 1.5 times its normal size.