An aneurysm is the abnormal swelling of a portion of a blood vessel. The aorta carries oxygen-rich blood away from the heart and is the largest artery in the body. The aorta's walls are made of three layers: a thin, inner layer; a muscular middle layer; and a fiber-like outer layer that gives the vessel strength to avoid bursting when the heart pumps blood to the body. Aortic aneurysms occur when a weakness develops in the wall of the aorta. Aneurysms can develop anywhere along the aorta, but most occur in the abdomen and are called abdominal aortic aneurysms. Aneurysms that occur in the part of the aorta that's higher up in the chest are called thoracic aortic aneurysms.
Aortic aneurysms can be difficult to detect because they can grow slowly and often without symptoms. Some aneurysms will never rupture. Many start small and stay small. Other aortic aneurysms enlarge slowly, increasing less than half an inch a year. Others expand at a faster rate, increasing the risk of rupture. As an aortic aneurysm grows, some symptoms may include:
- A pulsating feeling near the navel, if the aneurysm occurs in the abdomen
- Tenderness or pain in the abdomen or chest
- Back pain
Abdominal Aortic Aneurysms
Although the exact cause of abdominal aortic aneurysms is unknown, there are a number of risk factors, including:
- Age - Aortic aneurysms occur most often in people age 60 and older.
- Cigarette smoking and other forms of tobacco use - Smoking also contributes to atherosclerosis and high blood pressure.
- High blood pressure
- Atherosclerosis - The buildup of fat and other substances can damage the lining of a blood vessel.
- Infection in the aorta (vasculitis) - In rare cases, aortic aneurysms may be caused by an infection or inflammation (vasculitis) that weakens a section of the aortic wall.
- Family history - Individuals with a family history of aneurysms may develop aneurysms at a younger age and are at higher risk of rupture.
Thoracic Aortic Aneurysms
In addition to the risk factors above, the following can put patients at higher risk for thoracic aortic aneurysms:
- Marfan syndrome - a genetic condition that affects the connective tissue in the body. Marfan Syndrome can cause weakness in the aortic wall, increasing the risk for aneurysm.
- Previous injury to the aorta
- Traumatic injury
Anyone age 60 and older who has risk factors for developing an aortic aneurysm should consider regular screening for the condition. Medicare offers a one-time screening for anyone with a family history of aortic aneurysms, and for men who smoke, as part of the Welcome to Medicare Program . If you have a family history of aortic aneurysm, your doctor may also recommend regular ultrasound exams.
Aortic aneurysms are often found during routine medical tests, such as a chest X-ray, ultrasound of the heart or abdomen, or CAT scan. Specialized tests can confirm an aneurysm. They include:
- Abdominal ultrasound - A small amount of warm gel is applied to the abdomen. The technician presses an wand-like instrument called a transducer against the skin over the abdomen, moving from one area to another. The transducer sends images to a computer screen that the technician monitors to check for a potential aneurysm.
- Computerized tomography (CT) scan - During a CT scan, the patient lies on a table inside a doughnut-shaped machine called a gantry. Numerous x-ray beams and a set of electronic x-ray detectors rotate around you, measuring the amount of radiation being absorbed throughout your body. A computer gathers these signals and assigns them a color ranging from black to white, depending on the signal intensity. The computer then assembles the images and displays them on a computer monitor. This test can provide the doctor with clear images of the aorta.
- Magnetic resonance imaging (MRI) - Most MRI machines contain a large magnet shaped like a doughnut or tunnel. The patient lies on a movable table that slides into the tunnel. The magnetic field aligns atomic particles in some of the cells. When radio waves are broadcast toward these aligned particles, they produce signals that vary according to tissue types. These signals then create computer images that can also provide clear images of the aorta.
The best approach to prevent an aortic aneurysm is to keep the blood vessels healthy by taking the following steps:
- Control blood pressure
- Don't smoke
- Get regular exercise
Tears in the wall of the aorta (dissection) and rupture of the aorta are the main complications of an abdominal aortic aneurysm. A ruptured aortic aneurysm can lead to life-threatening internal bleeding. Signs and symptoms of an aortic tear include:
- Sudden, intense and persistent abdominal, chest or back pain
- Severe back pain
- Severe abdominal pain
- Low blood pressure
- Fast pulse
- Loss of consciousness
- Small aneurysm - A small aneurysm is less than 1.6 inches (4.5 centimeters) in diameter. If no symptoms are evident, a doctor may choose to monitor the aneurysm with periodic ultrasounds, usually every six to 12 months.
- Medium aneurysm - A medium aneurysm typically measures from 1.6 and 2.2 inches (4.5 and 5.5 cm). At this stage, a physician will discuss with a patient the risks of surgery versus waiting.
- Large or fast-growing aneurysm - If an aneurysm that is larger than 2.2 inches, or 5.5 cm, or growing rapidly (more than 0.5 cm over six months), is leaking, tender or painful, surgery is likely to repair the aortic aneurysm. This is open-heart surgery that involves removing the damaged section of the aorta and replacing it with a synthetic blood vessel (graft), which is sewn into place. Another less-invasive option may be placement of an endovascular stent graft. Learn more...