An aneurysm is a weak point in a blood vessel wall, most commonly in an artery. Blood pressure tends to push the weakened section of an arterial wall outward, forming a balloon-like projection. This condition by itself isn't especially harmful if it remains relatively small, but the artery is prone to rupture. A ruptured aneurysm breaks the artery and allows uncontrolled bleeding to occur, which can be fatal.
Aneurysms can form in different places. The most common type of aneurysm is an abdominal aortic aneurysm (AAA). The aorta is the body's largest artery, carrying blood from the heart to every organ except the lungs. It leaves the heart flowing upwards in the chest, makes a U-bend, and flows down the spine from the chest to the abdomen. Several branches leave the aorta in the abdomen, going to the kidneys, liver, and intestines. These branch points are prime sites for aneurysms.
Other locations for aneurysms are:
- the blood vessels within the brain – the most common type of cerebral (brain) aneurysm is called a berry aneurysm
- thoracic aortic aneurysm (the thorax is in the chest) – of the thoracic aneurysms, the most common subtype is the aneurysm of the ascending aorta (between the heart and the U-bend)
Aneurysms tend to occur in older Caucasian men; women are less at risk. By age 80, over 5% of Caucasian men have developed an aneurysm. People of African descent rarely develop aneurysms.
Abdominal aortic aneurysms occur in 4% to 8% of men 65 and older, and in 0.5% to 1.5% of women 65 and older. They rarely occur in people under the age of 55. Unfortunately, 80% to 90% of people who experience a ruptured abdominal aortic aneurysm die from it.
A person's risk of developing an aneurysm may be inherited. Ascending aortic aneurysms and berry aneurysms are especially likely to run in families. The men of an affected family are more likely to develop aneurysms than are the women. Scientists haven't yet identified the responsible genes in humans, though they have identified some in mice.
Most ascending aortic aneurysms are a result of aging associated with heart disease risk factors. Some aneurysms are a result of genetic diseases such as Marfan's syndrome. People with Marfan's syndrome are unusually tall with long extremities. Abraham Lincoln is thought to have had this syndrome. They also have a weakness in the aortic wall, just where the aorta leaves the top of the heart.
Two other types of aneurysms are mycotic and atherosclerotic aneurysms. Mycotic aneurysms are caused by a bacterial or fungal infection. Almost any such organism can damage the arteries, but the infection must be very deep and severe. The bacteria salmonella and syphilis both seem to have a special liking for arterial walls.
Atherosclerotic aneurysms are linked to the process that causes coronary artery disease, which is the buildup of fatty deposits on the inner wall of the arteries. This can result in weakening of the vessel wall. However, the correlation is still not fully understood, since someone with severe atherosclerosis may not develop an aneurysm if they are not already genetically predisposed.
Risk factors for heart disease, such as high blood pressure, high cholesterol, inactivity, smoking, and obesity, are also risk factors for aneurysms. Severe aneurysms are probably due to a combination of genes and poor cardiovascular health. Occasionally, aneurysms develop where stab or gunshot wounds have perforated an artery.
Symptoms and Complications
Aneurysms often cause no pain. They're sometimes detected accidentally in body scans. The most likely way you will notice a cerebral, thoracic, or abdominal aneurysm is if it grows big enough to press against nerve-bearing tissue or has ruptured resulting in significant bleeding. Unfortunately, this means the aneurysm has grown recently, so the warning comes late. Fast-growing aneurysms are the ones most likely to rupture. Even large aneurysms often cause no symptoms.
Cerebral (brain) aneurysms occasionally cause some of these symptoms as they start to swell:
- double vision
- facial pain
- loss of vision
- severe headaches from minor bleeding
- tremors or uncontrollable movement of an eye or eyelid
With thoracic aneurysms, symptoms are rare but may include:
- chest pain, upper back pain, or both
- coughing up of blood
- difficulty swallowing
- Horner's syndrome – drooping eyelid, absence of sweating on one side of the face
Abdominal aneurysms are more likely to cause symptoms that:
- give a pulsing sensation in the abdomen
- cause upper abdominal pain, severe lower back pain, or both
The symptom of a ruptured abdominal aneurysm is intense pain and tenderness in the stomach or lower back area. Ruptured thoracic aneurysms cause excruciating pain in the upper chest that spreads to the back and sometimes down the trunk. Blood loss and failure of vital organs such as the kidneys can lead to fatal consequences in cases of thoracic and abdominal aneurysms. Ruptured cerebral aneurysms cause a hemorrhagic stroke, with all of its symptoms.
Making the Diagnosis
Sometimes, you'll feel symptoms that will alert your doctor to a possible aneurysm, or your doctor may feel the pulsations of the larger abdominal aneurysms with their hands when they examine the upper abdomen. They may also hear a murmur in the area as a result of turbulent blood flow. In either case, your doctor will order a scan. Ultrasound, magnetic resonance imaging (MRI), and computed tomography (CT) scans can all locate aneurysms.
Treatment and Prevention
If the aneurysm is discovered while it is still small and there are no symptoms, your doctor will generally recommend a watch-and-wait approach. This includes repeat exams and scans every 6 to 12 months. Depending on the location of the aneurysm, medications such as beta-blockers can be used to reduce the progression of an aneurysm, especially those in the aorta. The treatment for a ruptured aneurysm is emergency surgery. The aneurysm is usually replaced with a synthetic graft or closed off with a clip. Sometimes a stent can be placed within the vessel to stabilize and close off the aneurysm. Treatment of a mycotic aneurysm involves taking antibiotics for a certain period of time, followed by removal of the aneurysm. Surgery is a lot safer if the aneurysm hasn't ruptured yet. If you're a man over 65 years of age and your family has a history of aneurysms or hemorrhagic stroke, you should ask for a screening scan.
Aneurysms under a certain size (their size depends on their location) rarely rupture. Abdominal aneurysms over 5.5 cm and thoracic aneurysms over 6 cm in diameter pose a real risk of rupture and are best treated surgically. Surgery to repair an aneurysm is major surgery and involves an incision. In some cases, surgeons have developed new techniques to close off the aneurysm without a large incision, by approaching them from the inside the artery (endovascular approach).
Screening for abdominal aortic aneurysm can be an effective way to help detect aneurysms early, especially for people who may be at risk (e.g., people with a history of smoking). If necessary, elective surgery can be performed to help prevent rupture of the aneurysm. Screening in men aged 65 to 74 years old can be effective to reduce the number of ruptures.
Whatever your genetic profile, you can reduce your risk of aneurysm and rupture by:
- eating a healthy diet rich in fruits and vegetables
- eating less salt
- losing weight
- quitting smoking
- keeping your blood pressure under control
The blood pressure-lowering medication propranolol* and other types of beta-blockers may reduce the risk of enlargement and rupture of detected aneurysms.
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