Abdominal Aortic Aneurysm (AAA)
The abdominal aorta runs from the heart down the center of the abdomen and is the main blood vessel that supplies blood to your body. The role of the abdominal aorta is to take blood from the heart and distribute it, via a network of branching blood vessels, to all of the body's organs. When an aneurysm occurs in the aorta below the heart, it is called an abdominal aortic aneurysm (AAA). An aneurysm is an enlargement or a ballooning of the aorta, and indicates that the walls of the aorta are weakening and thinning. The puts the aneurysm in danger of rupture and life-threatening bleeding into the abdomen. Only 20% of people with a ruptured abdominal aortic aneurysm will survive.1
What is an Aneurysm?
An aneurysm is a bulge in a blood vessel that is caused by a weakness in the wall. In some people, as they get older, the wall of the aorta in the abdomen can become weak. As the blood runs through the weakened blood vessel, the pressure of the blood causes the blood vessel to bulge outwards like a balloon. If you have an aneurysm, you will not generally notice any symptoms.
Because most abdominal aortic aneurysms do not produce clear symptoms, there is a high rate of sudden rupture with significantly high mortality rate (80%).1
A healthy abdominal aorta has a diameter of 2-3cm (one inch). If an aneurysm develops, the diameter of the aorta may increase. The increase in diameter weakens the walls of the aorta, increasing the risk of the aorta rupturing (splitting). AAAs vary in size. As a rule, once you develop an AAA, it tends to gradually get larger. The speed at which it gets larger varies from person to person. However, on average, an AAA tends to get larger by about 10% per year. A ruptured aortic aneurysm can cause massive internal bleeding and requires prompt emergency treatment to prevent death.
What Causes an Abdominal Aortic Aneurysm?
Most of the time, it is not clear why an abdominal aortic aneurysm develops. Aneurysms can affect people of any age or gender. However, they are more common in men than in women, adults with high blood pressure (hypertension) and people over the age of 65.
Genetic make-up also plays a part—people who have an immediate relative (parent, brother or sister) who has had an abdominal aortic aneurysm are much more likely to develop one themselves. Certain other risk factors increase the chance of getting an aneurysm; these include smoking, high blood pressure, high cholesterol, emphysema and obesity.
Diagnosis of an Abdominal Aortic Aneurysm
A painless ultrasound scan is the easiest way to detect an AAA. It is the same type of ultrasound that pregnant women have to look at the baby in the womb. The size of the aneurysm can also be measured during the ultrasound exam. Sometimes a doctor feels the bulge of an aneurysm during a routine examination of the abdomen. However, most AAAs are too small to feel. An X-ray of the abdomen (often done for other reasons) may show calcium deposits lining the wall of an abdominal aortic aneurysm in some, but not all, cases.
A more detailed scan such as a CT scan is sometimes done. This may be done if your doctor needs to know whether the aneurysm is affecting any of the arteries that come off the aorta. For instance, if the aneurysm involves the section of the aorta where the arteries to the kidneys branch off then surgeons need to know this information if they plan to operate.
Who is at Risk of an Abdominal Aortic Aneurysm?
Abdominal aortic aneurysms tend to be more common among people age 65 and over. Smoking has been found to be a major risk factor for AAA formation2. Each year, approximately 15,000 Americans die of a ruptured aortic aneurysm. When detected in time, an aortic aneurysm can usually be repaired with surgery. Only approximately 50% of patients with ruptured AAAs reach the hospital alive; of those who reach the hospital, up to 50% do not survive repair2.
Treatment of an Abdominal Aortic Aneurysm
Surgery to repair an aneurysm (before rupture) is recommended when it is thought that the risk of the aneurysm rupturing is high enough to outweigh the risks associated with having surgery. A physician's recommendation will be based on several factors, including these:
- The size of the abdominal aortic aneurysm—only aneurysms of a certain size will be recommended for surgery; smaller aneurysms will be monitored for change.
- How quickly the aneurysm is growing
- Gender – for reasons that are unclear, the risk of an aneurysm rupturing is four times higher in women
- Family history of ruptured aneurysm
When surgery is not recommended, physicians may prescribe beta blockers, antibiotics to reduce inflammation, and risk factor reduction, including:
- Maintaining a healthy weight, with a BMI of 25 or lower. Calculate your BMI here
- Eating a heart-healthy diet along the lines of the DASH diet, which is described here
- Complete cessation of smoking
- Management of high blood pressure
- Gentle exercise such as walking and cycling are recommended to help to improve fitness
- Management of diabetes
1 American Heart Association, https://www.heart.org/en/health-topics/aortic-aneurysm/types-of-aneurysms
2 Aggarwal S, Qamar A, Sharma V, Sharma A. Abdominal aortic aneurysm: A comprehensive review. Exp Clin Cardiol. 2011;16(1):11–15, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3076160/