Aneurysm

Definition

An aneurysm is an abnormal enlargement, distention, dilation, bulging, or ballooning of the wall of an artery.

Description

Aneurysms affect arteries throughout the body, including the brain (cerebral aneurysm), the leg (popliteal artery aneurysm), the intestine (mesenteric artery aneurysm), and the aorta (abdominal or thoracic aortic aneurysm).

An aneurysm occurs when the pressure of blood passing through a section of weakened artery causes the vessel wall to bulge outward, forming a sort of balloon. Aneurysms are serious because they increase the risk of blood vessel rupture and subsequent bleeding into tissues. If the bulging stretches the arterial wall excessively, the artery may burst, causing a person to bleed to death. Rupture of a cerebral aneurysm results in stroke, the loss of blood supply to brain tissue resulting in the death of brain cells. As a rule, the larger the size of an aneurysm, regardless of location, the greater the chance it will ultimately bleed.

The aorta is the largest artery in the body. It arises from the left ventricle of the heart, ascending and bending over to descend through the chest and abdomen, and ends by dividing into two arteries called the common iliac arteries that go to the legs. Aortic aneurysms can be abdominal when they occur in the area below the stomach, or thoracic when they occur in the chest. Abdominal aortic aneurysms are the most common aneurysms. They increase in

frequency and size with age, and expand much more rapidly than thoracic aortic aneurysms.

Demographics

Aneurysms are relatively common in people over 65 years of age. Risk indicators for some groups such as Caucasian males begin to increase at age 55. Some studies indicate that up to 5% of the population over 65 suffer some form of aneurysm. The patient population for aortic aneurysm repair is typically male with an average age of 65. In the past 30 years, the occurrence of this type of aneurysm has increased threefold. About 15,000 Americans die each year from ruptured aortic aneurysms. According to the American Association of Neurological Surgeons, every year, an estimated 30,000 people in the United States experience a ruptured cerebral aneurysm, and up to 6% of the population may be living with an unruptured aneurysm. Cerebral aneurysms occur in all age groups, but increase steadily for individuals age 25 and older. They are most prevalent in people ages 50 to 60, and about three times more prevalent in women.

Causes and symptoms

Aneurysms are caused by any condition that can weaken the walls of arteries. These include:

• Atherosclerosis, the clogging, narrowing, and hardening of arteries.
• High blood pressure (hypertension).
• Traumatic injuries, or infections of the blood vessels.
• Congenital defect in the structure of the muscular wall of arteries.

Research appears to show that some individuals have a genetic susceptibility to aneurysms. The genetic inheritance patterns have characteristics linked to an autosomal dominant gene. Within some families, rates of aneurysms can run as high as five to 10 times those found in the general population.

Prior to rupture, the symptoms associated with an aneurysm depend upon its location, size, and rate of expansion. A static aneurysm that does not bleed or adversely affect cerebral circulation or neighboring tissue may be without symptoms. In contrast, larger aneurysms or aneurysms which expand rapidly may result in symptoms such as swelling, loss of sensation, blurred vision, etc.

Just before an aneurysm rupture, patients typically experience some symptoms commonly associated with stroke. Depending on the size and location of the aneurysm about to rupture, a patient may suffer a severe headache, deterioration or disturbances of hearing, double vision, severe nausea and vomiting, and fainting .

Diagnosis

Aneurysms can be diagnosed by physical examination, chest or stomach x ray, or by using ultrasound. The size and location can be determined using echocardiography or imaging techniques, such as arteriography, magnetic resonance imaging (MRI), and computed tomography (CT) scanning, and computerized tomographic angiography (CTA).

Treatment

Treatment depends on the size and location of the aneurysm and the overall health of the patient. The two main treatment options are surgery and medications. Medications such as beta blockers and calcium channel blockers are used to lower pressure, relax blood vessels, and decrease the risk of rupture.

Abdominal aortic aneurysms require surgical repair with the two main procedures being open chest repair and endovascular repair. The first involves a major incision in the abdomen or chest under general anesthesia to remove the aneurysm and repair the aorta. In endovascular repair, the aneurysm is not removed, but a graft is inserted into the aorta to strengthen it.

A small cerebral aneurysm that has not burst may not need treatment. Treatment for ruptured cerebral aneurysms aims to stabilize the patient by maintaining an adequate heart rate and respiration while simultaneously seeking to decrease intracranial pressure. Surgery is often performed as soon as the patient is stabilized, ideally within 72 hours of the onset of rupture to expose the aneurysm and allow the placement of a clip across a strong portion of the vessel to obstruct the flow of blood through the weakened aneurysm. Repeat surgical procedures to seal an aneurysm are not uncommon.

Nutrition/Dietetic concerns

Some research reports have suggested that supplementation with micronutrients with antioxidant properties could minimize the decreases in muscle strength and physical function associated with abdominal aortic aneurysms. A recent study, performed in 2002, supplemented patients with a combination of vitamins and trace elements that included beta-carotene, vitamin C, vitamin E , selenium, and zinc . Results showed that supplementation had limited, but noticeable beneficial effects on strength and physical function following surgery.

Therapy

Cerebral aneurysm patients may be require therapy after surgery. Rupture patients who have experienced bleeding may have some short or long term neurological deficits to varying degrees. In many cases, these deficits will decrease over time or disappear altogether. Physical, speech and occupational therapists can help patients regain neurological functions that may have been affected.

Prognosis

The overall prognosis for a cerebral aneurysm depends on several factors including the size, location, and stability of the aneurysm. Outcomes also depend on the patient's general health, neurological health, and age. With successful surgical repair, the outlook is often excellent. Although each aneurysm must be individually evaluated, in general, the prognosis for patients who have suffered a bleed is, however, guarded with mortality rates up 60% within a year of the initial bleeding incident. Approximately half of the survivors suffer some long-lasting disability. Patients with cerebral aneurysm can, however, fully recover with no long-lasting disorder.

Data regarding the prognosis for unruptured aneurysms is more tentative and not specific for cerebral aneurysms. Some long-term studies suggest that only 10% of patients might suffer leakage or bleeding from their aneurysm over a period of 10 years and only about a quarter of patients would experience bleeding from the aneurysm over a period of 25 years.

Prevention

Aneurysms cannot be prevented, but in 2005, the United States Preventive Services Task Force has recommended that men between the ages of 65 and 75 who are or have been smokers should have a one-time ultrasound to screen for abdominal aortic aneurysm. It is to be hoped that the same recommendation will be extended to women with a history of smoking . It has been suggested that control of high blood pressure may help prevent some aneurysms.

Caregiver concerns

Aging is recognized as a significant factor in the development of aneurysms. Aortic aneurysms rarely produce clear-cut symptoms and are usually found during examinations done for other reasons. When symptoms occur, they most commonly include general complaints of abdominal or chest pain or discomfort. Hence, caregivers should investigate such complaints thoroughly in the senior age group.

KEY TERMS

Aorta —The largest artery in the body, arising from the left ventricle of the heart, ascending and bending over to descend through the chest and abdomen to end by dividing into two arteries called the common iliac arteries that go to the legs.

Cerebral artery —Any of the arteries supplying blood to the cerebral cortex.

Computerized tomographic angiography (CTA) —Imaging method that combines the technology of a conventional CT scan with that of traditional angiography to create detailed images of the blood vessels in the body.

Distention —Swelling or enlargement of a tissue due to internal pressure.

Ultrasound —The use of ultrasonic waves to image an internal body structure.

QUESTIONS TO ASK YOUR DOCTOR

• What type of aneurysm do I have?
• What tests do I need?
• Am I at risk for complications?
• What happens during a CT angiography?
• What is aneurysm repair?
• What are the treatment options?

Resources

BOOKS

Hakaim, Albert G., editor. Current Endovascular Treatment of Abdominal Aortic Aneurysms. New York, NY: Wiley-Blackwell, 2005.

Khurana, Vini G., and Robert F. Spetzler. The Brain Aneurysm. Bloomington, IN: AuthorHouse, 2006.

Nussbaum, Eric S. Brain Aneurysms and Vascular Malformations. Philadelphia, PA: Xlibris Corporation, 2000.

Siles, Madonna, and Lawrence J. Beurel. Brain, Heal Thyself: A Caregiver's New Approach to Recovery from Stroke, Aneurysm, And Traumatic Brain Injuries. Charlottesville, VA: Hampton Roads Publishing Company, 2006.

PERIODICALS

de Donato, G., et al. “Abdominal aortic aneurysm repair in octogenarians: myth or reality?” Journal of Cardiovascular Surgery 48, no. 6 (December 2007): 697–703.

Geraghty, P. J. “Minimally invasive approaches to vascular procedures in the elderly.” Clinical Geriatric Medicine 22, no. 3 (August 2006): 575–584.

Goto, T., et al. “Gender differences in stroke risk among the elderly after coronary artery surgery.” Anesthesia and analgesia 104, no. 5 (May 2007): 1016–1022.

Rix, T. E., and T. Bates. “Pre-operative risk scores for the prediction of outcome in elderly people who require emergency surgery.” World Journal of Emergency Surgery 5 (June 2007): 2–16.

OTHER

Aneurysm. Medline Plus Fact Sheet. (February 20, 2008) http://www.nlm.nih.gov/medlineplus/ency/article/001122.htm

Aneurysm Repair. Texas heart Information Center. (January 30, 2008) http://www.texasheartinstitute.org/HIC/Topics/Proced/asurg.cfm

Aneurysms. Medline Plus Health Topic. (February 20, 2008) http://www.nlm.nih.gov/medlineplus/aneurysms.html

Minimally Invasive Surgery Fixes Aneurysms. Health Day. (January 30, 2008) http://www.nlm.nih.gov/medlineplus/news/fullstory_60612.html

ORGANIZATIONS

American Stroke Association: A Division of American Heart Association, 7272 Greenville Ave., Dallas, TX, 75231-4596, (414) 272-6071, (888) 4STROKE, (214) 706-5231, http://www.strokeassociation.org.

Brain Aneurysm Foundation, 612 East Broadway, South Boston, MA, 02117, (617) 269-3870, [email protected], http//www.bafound.org.

National Institute of Neurological Disorders and Stroke (NINDS), P.O. Box 5801, Bethesda, MD, 20824, (301) 496-5751, (800) 352-9424, http://www.ninds.nih.gov.

National Stroke Association, 9707 East Easter Lane, Englewood, CO, 80112-3747, (303) 649-9299, (800) STROKES, (303) 649-1328, [email protected], http//www.stroke.org.

Monique Laberge Ph.D.