Chapter 30

### INTRODUCTION

The abdominal aorta is frequently affected by both degenerative and occlusive disease. Since these diseases of the aorta frequently afflict the elderly, and with an aging U.S. population, surgical and endovascular treatment of aortic disease is common in a vascular specialist's practice. Approximately 42 000 operations for the treatment of abdominal aortic aneurysms (AAA) were performed in the United States in 2003.1,2 Though in the past open surgical therapy for aortic diseases was the primary therapy, endovascular therapy of aortic diseases has emerged as an acceptable alternative to open aortic reconstruction and expanded the treatment options for those who treat aortic lesions. Advances in graft materials, surgical technique, and perioperative care have led to a marked reduction in perioperative morbidity and mortality with improvements in long-term results. With proper patient selection and appropriate procedure choice, the management of aortic diseases is one of the most rewarding areas of a modern vascular specialist's practice.

### ANATOMY

The abdominal aorta is the final segment of the aorta and the continuation of the thoracic aorta beginning at the median aortic hiatus and terminating at the level of fourth lumbar vertebra by dividing into two common iliac arteries. The average diameter of the abdominal aorta is 2 cm (range of 1.4–3 cm). The abdominal aorta is frequently classified as suprarenal or infrarenal segments (Figure 30.1). The branches of the abdominal aorta are subdivided as either ventral, lateral, or dorsal. The ventral branches are unpaired visceral branches consisting of the celiac artery, the superior mesenteric artery, and the inferior mesenteric artery. The lateral branches are primarily paired visceral branches including the suprarenal artery, renal artery, and ovarian or testicular arteries. The inferior phrenic artery is also a lateral branch but is a paired parietal branch. The lumbar and sacral arteries are the dorsal branches of the abdominal aorta.

###### FIGURE 30-1.

Abdominal aorta and its relation to its surrounding structures.

### ABDOMINAL AORTIC ANEURYSMS

Though obstructive, atherosclerotic changes of the abdominal aorta are a frequent finding in the aging population, AAA is the most common disease of the abdominal aorta that requires treatment. First described by Vesalius, a 16th century anatomist, AAAs are defined by a diameter 50% greater than the expected diameter. This is frequently accepted to be a size of 3 cm or greater. When less than 50% diameter enlargement is encountered, it is defined as arteriomegaly or ectasia.

#### Pathogenesis

More than 90% of all AAAs are caused by degenerative changes of the aortic wall. However, atherosclerosis cannot be the sole factor leading to AAA development. Since the atherosclerosis theory does not completely explain the development of either occlusive or aneurysmal changes in the aorta of similar patients, aneurysmal changes of the abdominal aorta must be ...

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