What is an abdominal aortic aneurysm (AAA)
What causes AAA, who is at risk, and how common are they
How will I know if I have an AAA
What are the symptoms of AAA
How is AAA treated
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View a brief video regarding AAA
View a brief video regarding open repair of AAA
View a brief video regaring endovascular repair of AAA
What is an abdominal aortic aneurysm (AAA)?
Arteries are the tubes carrying blood from the heart to the rest of the body. An aneurysm is a weak area in the wall of an artery that can bulge like a balloon, and can cause problems related to either bleeding or blood clotting. Aneurysms can occur throughout the body, but the most common locations are in the aorta and in the blood vessels of the brain. These two types of aneurysms are very different, and the remainder of this discussion will focus on aneurysms of the aorta.
The aorta is the largest artery of the body, carrying blood directly from the heart through the chest and abdomen (belly) to the rest of the body. Aneurysms of the aorta can occur in the chest (thoracic aortic aneurysm), but are most commonly seen in the abdomen and are referred to as abdominal aortic aneurysms (AAA). The area of the aorta most often involved with aneurysms is below the kidney arteries and the area where the aorta divides into the iliac arteries which bring blood to the pelvis and legs.
Aneurysms of the aorta are worrisome because they can burst (or rupture) resulting in excessive bleeding and usually causing death. The risk of aneurysm rupture is related to the size or diameter of the aneurysm. The normal diameter of the aorta in this region is about 1 inch or less (2.0 – 2.5 cm). Aneurysms less than 5 centimeters (2 inches) rarely rupture and require only close monitoring. If the aneurysm enlarges however, the risk of rupture and life-threatening bleeding (hemorrhage) increases. In most cases, physicians recommend treating aneurysms that are 5.5 centimeters or greater in diameter.
What causes AAA, who is at risk, and how common are they?
The exact cause of an aortic aneurysm remains under investigation. Smoking appears to be the most tightly associated risk factor and results in breakdown of the structural components in the aortic wall similar to the changes which can occur in the lungs. Weakness of the structural components can also run in families, and therefore a family history of aortic aneurysm is an important risk factor. Other risk factors to be considered are similar to those for heart disease including hypercholesterolemia and high blood pressure.
The likelihood of having an AAA increases with age, and AAA occurs 4 to 5 times more commonly in men than in women. Nearly 10% of men over the age of 65 with a long history of smoking will have some dilatation of their aorta, although not all of these will be of a dangerous size. Unfortunately, many people do not know they have an aneurysm until the day it ruptures and kills them. The condition accounts for nearly 15,000 deaths each year making it the 13th leading cause of death in the United States. Approximately one in every 250 people over the age of 50 will die of a ruptured AAA.
Fortunately, when AAA is diagnosed early it can be successfully treated preventing rupture and death.
How will I know if I have an AAA?
If you are in a high-risk category for AAA, you should discuss with your care provider whether you should be tested for this condition. Any person over the age of 60 and with a 1st degree relative (parent or sibling) with a known AAA is at risk. Also, any male over the age of 60 with a long smoking history is at risk. A careful physical examination can detect some abdominal aneurysms, however many AAAs can not be felt on examination and can only be detected by some form of imaging study.
There are a number of imaging exams that can be used to detect and further evaluate the aorta. Abdominal ultrasound is the most common test to screen for AAA, and monitor aneurysms that are not large enough to require repair. This is a safe, painless procedure in which a transducer (a device about the size and shape of a computer mouse) is passed over the abdomen. The transducer detects sound waves that are used to create a computerized picture of the aorta.
Computed tomographic (CT) scans are nearly always obtained once an aneurysm large enough to warrant repair has been detected. This x-ray study is usually performed with intravenous contrast to enhance the pictures. Aside from the intravenous catheter, this is a painless study that provides high resolution pictures of the aorta, including details necessary to plan the aneurysm repair. The test is obtained by lying on a table that moves through a machine housing the x-ray unit. The test takes less than 1 hour and has only slight risks associated with the use of intravenous contrast and x-rays.
Other tests such as Magnetic resonance imaging (MRI) or Artergraphy may be ordered by your health care provider under special circumstances. These tests are used less commonly for AAA as CT scans have become highly accurate in providing the necessary information needed to plan aneurysm repair.
What are the symptoms of AAA?
AAA is usually a silent disease, and most patients do not experience any symptoms whatsoever. If there are symptoms, they may be vague and may go on for some time without being attributed to the aneurysm. The most common symptoms are:
- abdominal pain that may be constant or come and go
- pain in the lower back that may radiate to the buttocks, groin ,or legs
- the feeling of a "heart beat" or pulse in the abdomen
- fatigue and / or weight loss
Unfortunately, the first symptom of an AAA may be at the time of rupture. A ruptured aneurysm is life threatening and requires immediate emergency care. Aneurysm rupture is usually accompanied by intense abdominal and or back pain, low blood pressure, and an episode of loss of consciousness. Some of the other symptoms of rupture may include:
- severe pain that begins suddenly
- rapid pulse
- dry mouth/skin and excessive thirst
- nausea and vomiting
- lightheadedness or fainting
- excessive sweating or clammy skin
How is AAA treated?
A small aneurysm may require no immediate treatment other than "watchful waiting". The aneurysm should be monitored by a vascular specialist who will order periodic ultrasound exams or other tests to make sure that the aneurysm is not growing. Many times aneurysms remain small and pose no significant problems.
If an aneurysm reaches a certain size between 5 and 5.5 cm, your health care provider may refer you for aneurysm repair. Aneurysms can be repaired in two ways, depending on the actual dimensions of the aneurysm and relation to surrounding structures, age and health of the individual, willingness to return for regular follow-up, and other factors.
Open Surgical Repair: Direct surgical repair of the aneurysm has been the standard approach for over 50 years. An incision is made in the abdomen, the aneurysm is isolated and opened, and a synthetic graft is sewn to the aorta. The vascular graft is usually made of a polyester type material, and essentially replaces the diseased portion of the aorta. This is a major surgery performed under general anesthesia. Recovery from the operation typically requires 7 to 10 days in the hospital and another 6 to 8 weeks of convalescence at home. Although this is a significant undertaking, results of this operation are generally good, and the chances of further problems are remote.
Endovascular Repair: This procedure has been developed over the past 10 – 15 years to repair an aneurysm with surgery that is less invasive. Incisions are made in the groins, and a device is maneuvered through the arteries to the area of the aneurysm under X-ray control. The device is deployed within the aneurysm, excluding it from the bloodstream. Recovery following this type of procedure is shorter than with an open repair, typically requiring several days in the hospital and several weeks of convalescence. Only about one-half of aneurysms are of the appropriate size and shape to allow this type of repair. The long term results following endovascular repair are less favorable, and therefore these devices require long term monitoring with CT scanning. This procedure is ideally suited for people with other serious medical problems who may be at increased risk of complications following open repair.
Which treatment is right for me?
The best treatment for an abdominal aortic aneurysm depends on a number of factors, including the size and location of the aneurysm, whether or not it is causing symptoms, and the age and general health of the patient. Many aneurysms can only be repaired with the open operation. While this is a major operation, the outcomes are generally very good. Other aneurysms may be candidates for either open or endovascular repair. Both approaches have advantages and disadvantages in this circumstance, and you should understand the pros and cons of both approaches before deciding how to proceed. You should discuss all of these factors and any other questions you have with your primary care physician and vascular specialist.
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