Abdominal aortic aneurysm (AAA)
An abdominal aortic aneurysm (AAA) is a ballooning of a portion of the aorta, the largest artery in the body. Aneurysms are the result of weakening and thinning of the aortic wall. When a portion of it stretches and swells to more than 50 percent of the original diameter, it is called an aneurysm. Aneurysms in the abdominal portion of the aorta — below the diaphragm — are the most common.
Rupture is the biggest threat posed by an aneurysm. A ruptured aneurysm that requires emergency treatment can lead to severe pain, internal bleeding, a sudden drop in blood pressure and, if not treated quickly, death. In the United States, ruptured aneurysms are the 10th-leading cause of death of men over the age of 50. However, women are also at risk.
Aneurysms that have been discovered prior to rupture need to be measured, closely monitored and evaluated for treatment. Small aneurysms, those less than five centimeters in diameter, can often be left untreated, yet observed periodically to check for growth.
The aorta, which carries oxygenated blood to the body, is divided into four parts: 1) the thoracic aorta, which rises up from the left ventricle of the heart; 2) the aortic arch, which curves like the hook connecting to the; 3) descending thoracic aorta, which extends downward through the chest cavity to the; 4) abdominal aorta. The abdominal aorta splits and becomes the left and right common iliac arteries, carrying blood to the pelvis and legs.
The exact cause of an abdominal aortic aneurysm (AAA) is unknown. However, the most common risk factors for AAA include:
- Age over 60 years
- Gender: AAA is five times more likely in men than in women
- Smoking: Smokers are eight times more likely to be affected
- History of heart disease or peripheral arterial disease (PAD)
- Hyperlipidemia (elevated levels of fat in the blood)
- High blood pressure (hypertension)
- Family history of AAA
Most abdominal aortic aneurysms (AAAs) are diagnosed using an ultrasound scan or with a CT scan, though they can also be diagnosed during a physical exam. The scans are simple, non-invasive exams conducted on an outpatient basis. These exams measure the diameter of AAAs — a key element in determining the best treatment. Many times, AAAs are discovered during imaging tests, such as X-rays or MRIs, that are being performed for other reasons.
The UC Davis Health System’s Vascular Laboratory uses ultrasound diagnostic imaging and other non-invasive testing methods to provide objective and reliable assessments for many types of vascular problems, including AAAs. Click here to learn more.
The risk of rupture is increased if an abdominal aneurysm is greater than five centimeters in diameter, about the size of a lemon, or if the aneurysm is rapidly increasing in diameter (greater than one centimeter per year). Slowly growing aneurysms should be closely monitored. Cessation of smoking and medication to control blood pressure may help to slow the rate of enlargement of an intact aneurysm. Elective surgical repair of the aorta is the only definitive cure. However, risk of rupture must be weighed against the risks associated with surgery and to the patient’s pre-existing conditions. Surgical procedures for the repair of abdominal aortic aneurysms have a high success rate, with more than 95 percent of patients making a full recovery.
Open surgical repair
During a traditional surgical repair, the surgeon makes an incision in the abdominal wall, removes the distended portion of the aorta and replaces it with a fabric graft shaped like a pair of trousers. The “waist” of the “trousers” is sewn to the aorta above the level of the aneurysm, and the “cuffs of the trouser legs” are sewn to the common iliac arteries. A hospital stay of between five and 10 days is usually required. Recovery and return to a normal routine takes one to two months.
Endovascular aneurysm repair (EVAR)
Endovascular aneurysm repair is a less-invasive surgical treatment that involves a small incision in the groin and the insertion of a stent graft (also called an endograft or endovascular graft) through a catheter placed in the femoral artery. The stent graft is expanded inside the aorta and held in place by metallic hooks or struts rather than stitches. The blood now flows through the stent graft, excluding blood flow from the aneurysm.
The hospital stay is usually one to two days and most patients return to their normal activities within about a week. However, EVAR may not be for everyone. The patient’s arterial anatomy must be compatible with the dimensions of one of the available stent grafts. The Vascular Center’s specialists have extensive experience with EVAR, routinely receiving referrals from area physicians faced with the most challenging cases. The Vascular Center offers EVAR with all of the FDA approved endografts.
Once an endograft has been placed, there is a need for long-term surveillance to ensure that the graft remains in the correct position, that flow through the graft is normal and that the aneurysm is not expanding. The schedule for post-operative surveillance imaging may vary, but usually tests are ordered at three, six and 12 months after the endograft is placed, then annually thereafter. Click here to learn more.