Abdominal Aortic Aneurysm

What is an abdominal aortic aneurysm?

Location of the aorta in the body

The aorta is the largest blood vessel in the body. It sends 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 possibly 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.

Different types of aortic anerysms

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 may be part of the cause. Atherosclerosis is a buildup of plaque. Plaque is a deposit of fatty substances, cholesterol, cellular waste products, calcium, and fibrin. It collects 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

  • Injury

  • 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, CT scan, or MRI that was done for other reasons. Since abdominal aneurysm may not have symptoms, it's called the "silent killer." This is because it may rupture before being diagnosed.

Pain is the most common symptom of an abdominal aortic aneurysm. The pain may be 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 feeling in the abdomen. It can feel like a heartbeat in the abdomen.

The symptoms of an abdominal aortic aneurysm may look like other health problems. See your healthcare provider for a diagnosis.

How are aneurysms diagnosed?

Your healthcare provider will ask about your medical history. He or she will give you a physical exam. You may have tests such as:

  • CT scan. This test uses X-rays and computer technology to make detailed images of any part of the body, including the bones, muscles, fat, and organs. CT scans are more detailed than standard X-rays.

  • MRI. This test uses large magnets, radio waves, and a computer to make detailed images of tissues in the body.

  • Echocardiogram (echo). This test looks at the structure and function of the heart. It uses sound waves recorded on an electronic sensor. It makes a moving picture of the heart and heart valves. It also shows the structures in 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 an aneurysm, see the heart valves, or look for a tear of the lining of the aorta. TEE is done by putting a probe with a transducer on the end down your throat.

  • Chest X-ray. This test uses a small amount of radiation beams to make images of tissues, bones, and organs onto film.

  • Arteriogram (angiogram). This is an X-ray image of the blood vessels. It 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?

Graft repair of abdominal aneurysm

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. Some things may help control the aneurysm. These include quitting smoking, and controlling blood sugar if you have diabetes. They also include losing excess weight, and eating a healthy diet.

  • Medicine. This is 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 aneurysm. A mesh, metal coil-like tube called a stent or graft may be used. This graft is sewn to the aorta, connecting 1 end of the aorta at the site of the aneurysm to the other end. The open repair is the standard method of surgery for AAA.

    • Endovascular aneurysm repair (EVAR). EVAR needs only small incisions in the groin. It's done with X-ray guidance and special tools. With these, 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.

Stent graft repair of abdominal aneurysm

A small aneurysm or 1 that doesn't cause symptoms may not need surgery until it reaches a certain size or is quickly getting bigger over a short time. Your doctor may advise "watchful waiting." This may include an ultrasound, duplex scan, or CT scan every 6 months to closely monitor the aneurysm. You may also take blood pressure medicine to control high blood pressure.

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

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 that separates the layers of tissues. This causes a weakening in the aortic wall that can rupture. Aortic dissection can be a life-threatening emergency. The most common symptom of an aortic dissection is sudden, severe, constant chest or upper back pain. It's sometimes described as "ripping" or "tearing." The pain may move from 1 place to another.

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

Illustration of aortic dissection

What causes aortic dissection?

The cause of aortic dissection is unclear. But several risk factors linked 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)

  • Injury

  • Coarctation of the aorta (narrowing of the aorta)

  • Excess fluid or volume in the circulation (hypervolemia)

  • Polycystic kidney disease (a genetic disorder that causes by the growth of many cysts filled with fluid in the kidneys)