Abdominal Aortic Aneurysm

Snapshot

• A 61-year-old man presents to the emergency department for vague abdominal and back pain. He says that his symptoms progressively worsened over the course of months and cannot identify an initiating cause. Medical history is significant for hypertension. He has been smoking 1 pack of cigarettes per day for the past 30 years. On physical exam, the patient has an enlarged pulsatile mass of approximately 5 cm in diameter. 

Introduction

• Clinical definition
  • a segmental and full thickness dilation of the abdominal aorta 
• Epidemiology
  • risk factors for AAA
    • age
    • male gender
    • tobacco smoking 
    • family history
    • Caucasian race
    • atherosclerosis
• Pathogenesis
  • pathoanatomy
    • the abdominal aorta is a retroperitoneal structure that
      • begins in the hiatus of the diaphragm
      • bifurcates into the right and left iliac common arteries
        • these arteries can also become aneurysmal
    • an aneurysm typically develops below the renal arteries and above the common iliac arteries 
  • pathophysiology
    • elastin fibers become disrupted and collagen becomes degraded, resulting in a loss of elasticity in the aortic wall
• Prognosis
• risk of rupture depends primarily on size (AAA with diameter >5.5 cm are at highest risk) 

Presentation

• Symptoms/physical exam
  • asymptomatic (the majority of cases)
    • an enlarged abdominal mass and an abdominal bruit may be found 
  • in symptomatic but not ruptured cases
    • abdominal, back, or flank pain
  • in symptomatic and ruptured cases 
• severe pain, hypotension, and a pulsatile mass

Imaging

• Abdominal ultrasound
  •  to screen for asymptomatic AAA in high-risk patients
• Abdominal CT (contrast-enhanced) 
• for symptomatic patients who are hemodynamically stable 

Treatment

• Operative
  • abdominal aortic aneurysm (AAA) repair
    • indication
      • ruptured AAA
      • symptomatic, unruptured AAA
• asymptomatic large AAA (>5.5 cm diameter)

Complications

• Rupture