An aneurysm is a bulge (dilation) in the wall of an artery.
(See also Aortic Branch Aneurysms.)
Aneurysms may occur in any artery. Aneurysms are most common in the aorta, which is the main artery that carries blood from the heart to the body. The aorta is located in the torso. Aneurysms may also occur in arteries outside the torso, including those in the
- Legs (femoral arteries in the thighs, popliteal arteries behind the knees)
- Heart (coronary arteries)
- Neck (carotid arteries)
- Brain (cerebral arteries)
Aneurysms of the carotid arteries are rare. Older people are more likely to have aneurysms than are younger people.
Many aneurysms result from a weakness in the artery wall that is present at birth (congenital) or from atherosclerosis (buildup of plaque or fatty material in the wall of blood vessels). Others result from injuries caused by stab or gunshot wounds or from bacterial or fungal infections in the wall of the artery that develop after recreational use of intravenous drugs such as heroin. Such infections usually start elsewhere in the body, typically in a heart valve, before spreading to the wall of the artery.
Most popliteal and femoral aneurysms do not cause symptoms. However, blood clots can form within the aneurysm. If these blood clots break loose, they are called emboli. Emboli can move with the blood flow until they block an artery in the lower leg or foot, causing sudden onset of severe pain, numbness, and coolness of the foot, which may also appear pale.
Emboli from carotid aneurysms can block an artery in the brain and cause a stroke.
Emboli from aneurysms in the arteries of the heart (coronary arteries) can result in symptoms of a heart attack (such as chest pain and shortness of breath).
Unlike aneurysms in the aorta or cerebral arteries, aneurysms in the popliteal, femoral, coronary, and carotid arteries rarely rupture.
Doctors may diagnose aneurysms in the legs or arms by feeling a pulsating mass in the affected artery. Ultrasonography or computed tomography (CT) can confirm the diagnosis. Aneurysms of arteries in the heart or brain require other imaging studies, such as conventional angiography, CT angiography, or magnetic resonance angiography.
- Surgery or stent-graft repair
Doctors repair aneurysms in the lower part of the body when the aneurysm is twice the size of the normal blood vessel or when the person develops symptoms. Aneurysms in the arms are usually repaired right away even if the person has no symptoms because there is a higher chance that a blood clot will form in these blood vessels.
For popliteal aneurysms larger than 1 inch (2.5 centimeters) in diameter, open surgery or placement of a stent-graft within the aneurysm is usually done. A stent-graft is a hollow tube of synthetic material with a springy mesh in its wall. The mesh wall, like a collapsible straw, allows the stent to be compressed small enough to be inserted into an artery over a long thin wire. Doctors pass the stent through the artery to the aneurysm. Then the stent-graft is opened, forming a stable channel for blood flow. Stent-grafts can also be used for coronary aneurysms, although these sometimes require coronary artery bypass surgery. Usually, femoral and carotid aneurysms are surgically repaired.
Infected aneurysms typically require treatment with antibiotics or antifungal drugs and may require surgery, depending on where the aneurysm is located, how big it is, and how much it has been damaged by the infection.
Aneurysms may also occur in the arteries of the brain (cerebral arteries).
Rupture of a cerebral aneurysm may cause bleeding into the brain tissue (intracerebral hemorrhage), resulting in a stroke. Because cerebral aneurysms are near the brain and are usually small, their diagnosis and treatment differ from those of other aneurysms. Larger unruptured cerebral aneurysms can push on brain tissue and nerves and cause headache, dilated pupils, and symptoms of a stroke, such as weakness or paralysis on one side of the body.
The diagnosis of a cerebral aneurysm is made by specialized computed tomography (CT) or magnetic resonance imaging (MRI) scans. These specialized scans are called CT angiography or magnetic resonance angiography.
Infected aneurysms of the cerebral arteries are particularly dangerous, making early treatment important. Diagnosis is made by CT angiography, blood tests that indicate increased levels of inflammation (such as an elevated C-reactive protein level or an elevated erythrocyte sedimentation rate), and blood cultures (samples of blood that are grown in a laboratory) that show the growth of microorganisms (such as bacteria or fungi).
Treatment of cerebral aneurysms often involves surgical repair of the aneurysm. Surgical repair involves placing a clip to close off the aneurysm. The clip is placed where the aneurysm pouches out from the main artery. Sometimes a less invasive treatment (endovascular coiling) can be done. Endovascular coiling involves inserting a small but long flexible plastic tube (catheter) into an artery in the thigh. The catheter is then pushed through the arteries of the body to the aneurysm in the brain artery. Small metal coils are injected through the catheter into the opening of the aneurysm to block blood flow into it, thereby allowing the aneurysm to shrink. When the aneurysm is infected, antibiotics or antifungal drugs are given.
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