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Causes and Incidence Most cases are caused by arteriosclerosis. Smoking and hypertension contribute to the formation of aneurysms. Trauma, syphilis, infection, connective tissue disorders, and arteritis are also causes. Aneurysms can develop anywhere along the aorta, but 75% occur in the abdominal aorta. About 25% develop in the thoracic aorta, and the remainder occur in peripheral aortic branches. White men over 40 years of age have the highest incidence of aortic aneurysms in the United States.

Disease Process With arteriosclerosis, fibrosis and intimal thickening develop as a result of long-term hypertrophy and atrophy of the smooth muscle coat, generally as a result of aging. The vessel becomes less elastic, and the vessel wall thins in spots. Pressure on these spots causes ballooning, which increases over time. Aneurysms caused by infection occur when the infection infiltrates and damages the aortic wall. Aneurysms caused by blunt chest trauma arise from damage to the aorta and subsequent leakage and hematoma formation.

Symptoms Many people are asymptomatic, even with huge aneurysms. Signs and symptoms, when present, are dictated by location and compression or erosion of adjacent tissues.

Abdominal

Deep, boring, steady visceral pain in lumbosacral area, often relieved by positioning; feeling of abdominal pulsation or pain; tenderness on palpation; wide aortic pulsation on palpation

Thoracic

Pain in spine or rib cage; cough; wheezing; hemoptysis; dysphagia; hoarseness; tracheal deviation; abnormal chest wall pulsations

Potential Complications The most serious threat posed by an aneurysm is rupture. Depending on the severity of bleeding, hypovolemic shock and death usually follow quickly. The success rate for surgery for a ruptured abdominal aortic aneurysm is only 50%.

Diagnostic Tests

Abdominal/chest x-ray

Calcification of aneurysm wall

Ultrasound/computed tomography/ magnetic resonance imaging

To determine extent and size of aneurysm

Contrast aortography

To determine origin of major vessels arising from aortic site; useful for resection

Treatments

Surgery

Resection and replacement with a synthetic conduit is recommended for all aneurysms .6 cm and for most 4-6 cm

Drugs

Intensive antibiotic therapy for mycotic aneurysms before resection

General

Monitoring if surgery is not done