Thoracic aortic aneurysms are bulges (dilations) in the wall of the aorta in the part that passes through the chest (thorax).
Thoracic aortic aneurysms may not cause symptoms, or they may cause pain, coughing, and wheezing.
When an aneurysm ruptures, it causes excruciating pain (beginning high in the back and spreading down the back and into the abdomen), low blood pressure, and death.
Aneurysms are often discovered by chance during an imaging procedure that is done for another purpose, but doctors do x-rays, computed tomography, or another imaging procedure to determine the size and precise location.
Doctors try to repair aneurysms surgically before the aneurysm ruptures.
The aorta is the largest artery of the body. It receives oxygen-rich blood from the heart and distributes it to the body through smaller arteries that branch off of it. The thoracic aorta is the part of the aorta that passes through the chest cavity.
Thoracic aortic aneurysms are being identified more often than in the past because computed tomography (CT) of the chest is used more widely for the diagnosis of other diseases.
In a common form of thoracic aortic aneurysm, the walls of the aorta degenerate (a condition called cystic medial necrosis), and the part of the aorta nearest the heart enlarges. This enlargement may cause a malfunction of the valve between the heart and the aorta (aortic valve), allowing blood to leak backward into the heart because the valve cannot close properly. This disorder is called aortic valve regurgitation.
About half of the people with an aneurysm plus cystic medial necrosis also have a connective tissue disorder called Marfan syndrome. In the other half, no cause is apparent, although many of these people have high blood pressure.
Rarely, syphilis causes an aneurysm to form in the part of the aorta nearest the heart. In other cases, bacteria can enter the bloodstream as a result of another infection (pneumonia or a urinary tract infection) and attach to a site in the aorta and multiply. This bacterial infection can weaken the aortic wall and result in an aneurysm at that site.
Thoracic aorta aneurysms that develop further away from the heart may result from a blunt injury to the chest, most often due to a motor vehicle crash.