Introduction to Abdominal Aortic Aneurysm

Types of Abdominal Aortic Aneurysm

There are various shapes which an abdominal aortic aneurysm (AAA) can assume including:

• Saccular aneurysm - appears as an outpouching arising from one part of the aorta, has a neck, and does not involve the entire circumference of the aorta.

• Fusiform aneurysm - this is tubular shaped, involves the entire circumference of the localized aorta, and has no neck.

• Mycotic aneurysm - a rare aneurysm caused by a fungal infection which may be associated with immunodeficiency, IV drug abuse, heart valve surgery.

• Pseudoaneurysm - only the outside layer of the aorta (tunica adventitia) is dilated

Many aneurysms begin as fusiform shaped with the proximal (closer to the heart) end just below the renal arteries and the distal end (away from the heart) towards the point where the aorta bifurcates (divides) into the iliac arteries. Aneurysms may become more spherical as they grow and they may become angulated or tortuous (e.g., they do not lay straight or they twist away from the midline).