29: ENDOVASCULAR ANEURYSM REPAIR

PATIENT STORY

A 65-year-old man presented to the vascular clinic after his primary care physician felt a pulsatile abdominal mass in his left mid abdomen. The patient was not having any abdominal pain or back pain. His past medical history was significant for hypertension, hyperlipidemia, and tobacco use. An abdominal ultrasound and computed tomographic angiogram (CTA) of the abdomen and pelvis were performed, which showed a 5.7-cm dilation of the infrarenal aorta beginning about 2 cm below the origin of the renal arteries.

This patient had an infrarenal abdominal aortic aneurysm (AAA). Most patients are asymptomatic on presentation. The goal of aneurysm repair is to prevent death from rupture.

EPIDEMIOLOGY

• The 15th leading cause of death in the United States is ruptured AAA.¹ Abdominal aneurysms are more common in males than in females and generally affect people over age 50. Incidence in the United States is approximately 6.5 per 1000 person-years.²

• AAA is defined as a dilation of all three layers of the abdominal aorta greater than 1.5× its native diameter.³

ETIOLOGY AND PATHOPHYSIOLOGY

• There appears to be a familial component to the development of AAA. People with an affected first-degree relative have an 11.6-fold increase in AAA risk.⁴

• The risk factors that have the greatest impact on AAA development appear to be age, male gender, family history, and smoking.⁵

• Most aneurysms are caused by a complex degenerative process.

• Patients with AAAs appear to have increased levels of metalloproteinases.⁶

• Aneurysms may develop in autoimmune inflammatory conditions or as a result of infectious etiology.⁷

DIAGNOSIS AND CLINICAL FINDINGS

• Nonruptured AAAs are usually asymptomatic and discovered incidentally on imaging obtained for workup of conditions that are unrelated.

• Sometimes a pulsatile mass in the mid abdomen may be felt by an examining physician or the patients themselves.

• Occasionally very large aneurysms may cause early satiety, nausea, vomiting, urinary symptoms, or venous thrombosis secondary to local compression of adjacent structures by the aneurysm.³

LABORATORY

• No specific laboratory tests are diagnostic.

• Blood chemistry including serum creatinine, complete blood count, and coagulation studies should be obtained in preparation for the repair.

IMAGING

Ultrasound

• Less expensive, noninvasive

• May underestimate the size of the aneurysm by 2 to 4 mm⁸

CT

• More expensive, risks associated with contrast and radiation exposure

• More accurate measurement of diameter⁸

Angiography

• Invasive

• Associated with contrast and radiation exposure

• Can be performed at the time of the repair

MANAGEMENT

• In general, although somewhat controversial, it may be safe to observe asymptomatic aneurysms less than ...