An aneurysm is a weak section of an artery wall. Pressure from inside the artery causes the weakened area to bulge out beyond the normal width of the blood vessel. An abdominal aortic aneurysm is an aneurysm in the lower part of the aorta, the large artery that runs through the torso.

Abdominal Aortic Aneurysm: What You Need to Know

• Abdominal aortic aneurysm is sometimes known as AAA, or triple A.

• Older, long-term smokers are at especially high risk for abdominal aortic aneurysm.

• Many people have no symptoms and don’t know they have an aortic aneurysm until it ruptures, which is often quickly fatal.

• Symptoms, when they do occur, include pain in the back or near the naval. An extremely sharp and severe pain may indicate rupture, requiring emergency medical treatment.

• Smaller, slow-growing aortic aneurysms may be treated with watchful waiting, lifestyle changes and medication. Large or fast-growing aortic aneurysms may require surgery.

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.

Abdominal Aortic Aneurysm Shapes

The more common shape is fusiform, which balloons out on all sides of the aorta. A bulging artery isn’t classified as a true aneurysm until it increases the artery’s width by 50 percent.

A saccular shape is a bulge in just one spot on the aorta. Sometimes this is called a pseudoaneurysm. It usually means the inner layer of the artery wall is torn, which can be caused by an injury or ulcer in the artery.

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.

What is the treatment for abdominal aortic aneurysms?

Treatment may include:

• Monitoring with MRI or CT. These tests are done to check the size and rate of growth of the aneurysm.

• Managing risk factors. Steps, such as quitting smoking, controlling blood sugar if you have diabetes, losing weight if overweight, and eating a healthy diet may help control the progression of the aneurysm.

• Medicine. Used to control factors such as high cholesterol or high blood pressure.

• Surgery:

  • Abdominal aortic aneurysm open repair. A large incision is made in the abdomen to let the surgeon see and repair the abdominal aorta aneurysm. A mesh, metal coil-like tube called a stent or graft may be used. This graft is sewn to the aorta, connecting one end of the aorta at the site of the aneurysm to the other end. The open repair is the surgical standard for an abdominal aortic aneurysm.

  • Endovascular aneurysm repair (EVAR). EVAR requires only small incisions in the groin. Using X-ray guidance and specially-designed instruments, the surgeon can repair the aneurysm by inserting the stent or graft inside the aorta. The graft material may cover the stent. The stent helps hold the graft open and in place.

A small aneurysm or one that doesn't cause symptoms may not require surgery until it reaches a certain size or is rapidly increasing in size over a short period of time. Your doctor may recommend "watchful waiting." This may include an ultrasound, duplex scan, or CT scan every 6 months to closely monitor the aneurysm, and blood pressure medicine may be used to control high blood pressure.

If the aneurysm is causing symptoms or is large, your doctor may recommend surgery.

Surgery

Surgery may be necessary if the aneurysm is large or fast growing, increasing chances of rupture. Women with large aneurysms are more likely than men to suffer a rupture.

For suprarenal (above the kidneys) AAA, only open surgery is available in the U.S. right now, though Johns Hopkins vascular surgeons are involved in endovascular device trials that may be a suitable option. However, AAA at or below the kidneys may be treated by open or endovascular surgery. Endovascular means “within the blood vessel” and is considered minimally invasive.

Not all patients can tolerate the risk of open surgery, so endovascular repair is a great option. Unfortunately, not all patients have the anatomy to qualify for endovascular repair. Consult your vascular surgeon about which technique is best for you.

• Open aneurysm repair: A large incision is made in the abdomen to repair the aneurysm. Another incision is made in the aorta for the length of the aneurysm. A cylinder called a graft is used for the repair. Grafts are made of polyester fabric or polytetrafluoroethylene (PTFE, nontextile synthetic graft). This graft is sewn to the aorta, from just above the aneurysm site to just below it. The artery walls are then sewn over the graft.

• Endovascular aneurysm repair (EVAR): A small incision is made in the groin. Using X-ray guidance, a stent graft is inserted into the femoral artery and sent to the site of the aneurysm. A stent is a thin metal mesh framework shaped into a long tube, while the graft, a fabric covering the mesh, is made of a polyester fabric called PTFE. The stent holds the graft open and in place.  EVAR is used only for an infrarenal (below the kidneys) AAA. It may be more easily tolerated by high-risk patients. However, the graft can sometimes slip out of place and may later need to be fixed.

• Fenestrated stent graft: When the aneurysm is juxtarenal (at the kidneys) or involves the arteries of the kidneys, the prior standard treatment has been open surgery. That’s because a traditional stent graft has no openings to accommodate the branching of the aorta to the kidneys. In 2012, the FDA approved a fenestrated stent graft, now available in a few vascular surgery programs, including Johns Hopkins. The fenestrated stent graft is made to the precise size of each patient’s aorta so the openings for the renal (kidney) arteries are in just the right place to maintain kidney circulation.

What is aortic dissection?

An aortic dissection starts with a tear in the inner layer of the aortic wall of the thoracic aorta. The aortic wall is made up of 3 layers of tissue. When a tear occurs in the innermost layer of the aortic wall, blood is then channeled into the wall of the aorta separating the layers of tissues. This generates a weakening in the aortic wall with a potential for rupture. Aortic dissection can be a life-threatening emergency. The most commonly reported symptom of an aortic dissection is sudden, severe, constant chest or upper back pain, sometimes described as "ripping" or "tearing." The pain may move from one place to another.

When a diagnosis of aortic dissection is confirmed, immediate surgery or stenting is usually done.

What causes aortic dissection?

The cause of aortic dissection is unclear. However, several risk factors associated with aortic dissection include:

• High blood pressure

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

• Cystic medial disease (a degenerative disease of the aortic wall)

• Aortitis (inflammation of the aorta)

• Atherosclerosis

• Bicuspid aortic valve (presence of only 2 cusps, or leaflets, in the aortic valve, rather than the normal 3 cusps)

• Trauma

• Coarctation of the aorta (narrowing of the aorta)

• Excess fluid or volume in the circulation (hypervolemia)

• Polycystic kidney disease (a genetic disorder characterized by the growth of numerous cysts filled with fluid in the kidneys)