15 Aneurysms
Overview/pathophysiology
An aneurysm is a pathologic enlargement of a section of an arterial wall. The most common cause is atherosclerosis, which alters the vessel pathology, weakening the vessel wall and allowing it to expand. Other causes include hereditary, age, lack of elastin, vessel wall trauma, congenital connective tissue disorders (e.g., Marfan’s syndrome), and infection, particularly syphilis or acquired immunodeficiency syndrome (AIDS). Undiagnosed and untreated aneurysms are at risk for rupture and embolization, thus early diagnosis is imperative. Although aneurysms can develop in any artery, the abdominal aorta is the most common site. Abdominal aortic aneurysms (AAAs) occur more often in men and represent approximately 80% of all aneurysms. As the aneurysm enlarges, the risk of rupture increases, especially if the aneurysm is larger than 5.5 cm.
Aneurysms in the thoracic aorta are most often caused by the risk factors of hypertension and cigarette smoking and are more susceptible to dissection. The atherosclerotic lesions present in dissecting aneurysms develop intimal tears, which allow bleeding into the layers of the vessel, causing false lumens to form that obstruct or limit blood flow in the true lumen of the vessel. This pathology is distinctly different from that of AAAs.
Early identification and periodic assessment of aneurysms are essential to prevent life-threatening rupture. Detection of aneurysms is most often found on physical examination and screening of patients at risk with ultrasound and computerized axial tomography (CT) scans.
Health care setting
Chronic aneurysms are often followed in primary care, with periodic radiographic or ultrasound testing. Elective surgical repair or emergent surgical care requires hospitalization and acute or intensive care during the perioperative period. Rehabilitation and home care services may be necessary during recovery.
Assessment
Abdominal aortic aneurysm:
A pulsatile, nontender mass may be palpated on both sides of the abdominal midline, although this is more difficult to assess in obese patients. Severe acute abdominal pain, of sudden onset with radiation to the back, may be indicative of aneurysm rupture and is a surgical emergency. Rupture carries a high mortality of up to 75% (Radvany et al., 2008).
Thoracic aneurysm:
Patients may be asymptomatic for years; however, pressure from the aneurysm on adjacent structures can result in dull pain in the upper back, dyspnea, cough, dysphasia, hemoptysis, tracheal deviation, and hoarseness. If there is pain associated with these aneurysms, it is more likely to be nonradiating central chest pain.
Femoral aneurysm:
Signs of decreased distal arterial blood flow may occur. These aneurysms can rupture or thrombose. See indicators discussed under “Atherosclerotic Arterial Occlusive Disease,” p. 138.
Acute indicators (rupture or dissection):
Sudden onset of severe pain often described as “tearing” or “ripping,” pallor, diaphoresis, and sudden loss of consciousness.
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