What is an abdominal aortic aneurysm?

The aorta is the largest blood vessel in the body. It delivers oxygenated blood from the heart to the rest of the body. An aortic aneurysm is a bulging, weakened area in the wall of the aorta. Over time, the blood vessel balloons and is at risk for bursting (rupture) or separating (dissection). This can cause life threatening bleeding and potentially death.

Aneurysms occur most often in the portion of the aorta that runs through the abdomen (abdominal aortic aneurysm). An abdominal aortic aneurysm is also called AAA or triple A. A thoracic aortic aneurysm refers to the part of the aorta that runs through the chest.

Once formed, an aneurysm will gradually increase in size and get progressively weaker. Treatment for an abdominal aneurysm may include surgical repair or removal of the aneurysm, or inserting a metal mesh coil (stent) to support the blood vessel and prevent rupture.

What causes an abdominal aortic aneurysm to form?

Many things can cause the breakdown of the aortic wall tissues and lead to an abdominal aortic aneurysm. The exact cause isn't fully known. But, atherosclerosis is thought to play an important role. Atherosclerosis is a buildup of plaque, which is a deposit of fatty substances, cholesterol, cellular waste products, calcium and fibrin in the inner lining of an artery. Risk factors for  atherosclerosis include:

• Age (older than age 60)

• Male (occurrence in males is 4 to 5 times greater than that of females)

• Family history (first degree relatives such as father or brother)

• Genetic factors

• High cholesterol

• High blood pressure

• Smoking

• Diabetes

• Obesity

Other diseases that may cause an abdominal aneurysm include:

• Connective tissue disorders such as Marfan syndrome, Ehlers-Danlos syndrome, Turner's syndrome and polycystic kidney disease

• Congenital (present at birth) defects such as bicuspid aortic valve or coarctation of the aorta

• Inflammation of the temporal arteries and other arteries in the head and neck

• Trauma

• Infection such as syphilis, salmonella, or staphylococcus (rare)

What are the symptoms of abdominal aortic aneurysms?

About 3 out of 4 abdominal aortic aneurysms don't cause symptoms. An aneurysm may be found by X-ray, computed tomography (CT or CAT) scan, or magnetic resonance imaging (MRI) that was done for other reasons. Since abdominal aneurysm may not have symptoms, it's called the "silent killer" because it may rupture before being diagnosed.

Pain is the most common symptom of an abdominal aortic aneurysm. The pain associated with an abdominal aortic aneurysm may be located in the abdomen, chest, lower back, or groin area. The pain may be severe or dull. Sudden, severe pain in the back or abdomen may mean the aneurysm is about to rupture. This is a life-threatening medical emergency.

Abdominal aortic aneurysms may also cause a pulsing sensation, similar to a heartbeat, in the abdomen.

The symptoms of an abdominal aortic aneurysm may look like other medical conditions or problems. Always see your doctor for a diagnosis.

How are aneurysms diagnosed?

Your doctor will do a complete medical history and physical exam. Other possible tests include:

• Computed tomography scan (also called a CT or CAT scan). This test uses X-rays and computer technology to make horizontal, or axial, images (often called slices) of the body. A CT scan shows detailed images of any part of the body, including the bones, muscles, fat, and organs. CT scans are more detailed than standard X-rays.

• Magnetic resonance imaging (MRI). This test uses a combination of large magnets, radiofrequencies and a computer to produce detailed images of organs and structures within the body.

• Echocardiogram (also called echo). This test evaluates the structure and function of the heart by using sound waves recorded on an electronic sensor that make a moving picture of the heart and heart valves, as well as the structures within the chest, such as the lungs and the area around the lungs and the chest organs.

• Transesophageal echocardiogram (TEE). This test uses echocardiography to check for aneurysm, the condition of heart valves or presence of a tear of the lining of the aorta. TEE is done by inserting a probe with a transducer on the end down the throat.

• Chest X-ray. This test uses invisible electromagnetic energy beams to make images of internal tissues, bones and organs onto film.

• Arteriogram (angiogram). This is an X-ray image of the blood vessels that is used to assess conditions such as aneurysm, narrowing of the blood vessel, or blockages. A dye (contrast) will be injected through a thin, flexible tube placed in an artery. The dye makes the blood vessels visible on an X-ray.