Page 64 - Critical Care Notes

4223_Tab02_045-106 29/08/14 10:00 AM Page 58

CV

Abdominal Aortic Aneurysm (AAA)
AAA is a localized, chronic abnormal dilation of an artery located between the
renal and iliac arteries with a diameter at least 1.5 times that of the expected
diameter and a natural history toward enlargement and rupture.
Pathophysiology
Atherosclerosis and destruction of elastin and collagen fibers in the vessel walls
contribute to its development.
Pathophysiology for Atherosclerosis
Fatty streaks deposited in arterial intima → stimulates inflammatory response
that causes proliferation → proliferation causes blood vessel to form fibrous
capillaries → deposits build up as atheromas or plaques → plaques pile up,
obstructing the blood flow → outpouching of abdominal aneurysm.
Pathophysiology Involvement with Elastin and Collagen
Media thins → decrease in elastin fibers in vessel walls → collagen weakens →
leads to aneurysm growth → outpouching of abdominal aorta.
Clinical Presentation

AAA may manifest as asymptomatic or symptomatic. When asymptomatic,
look for a pulsatile, periumbilical mass with or without a bruit. When sympto-
matic, symptoms include:
■ Sudden, severe constant pain in the abdomen, flank, groin, or back
■ Early satiety, gastric or abdominal fullness, nausea and vomiting, GI bleeding
■ Syncope
■ Unequal carotid pulses and different BP in right and left arms
■ ↓ peripheral circulation, venous thrombosis, lower extremity ischemia
■ Symptoms of shock with rupture
AAA can also mimic:
■ Urinary tract infection
■ Renal calculus or obstruction
■ Ruptured disc
■ Diverticulitis
■ Pancreatitis
■ Incarcerated hernia
■ Abdominal neoplasm
■ Peptic ulcer perforation
58