ANEURYSM, ABDOMINAL AORTA

An abdominal aortic aneurysm is an abnormal localized dilation of the aorta. The aorta is the largest artery in the body and is divided into the ascending aorta, aortic arch, and the descending aorta. The aorta usually measures about 3 cm, or just over 1 inch, wide. The ascending aorta is located in the chest and is attached to the heart; it measures approximately 2 to 2½ inches in length. The aortic arch, as its name states, arches around the chest from right to left behind the upper part of the sternum (chest bone). The descending aorta travels down from the chest into the abdomen before it divides into the arteries that lead to the lower legs.

Abdominal aortic aneurysms commonly occur in people over the age of 60 years and affect men more often than women at a ratio of 4:1. Aneurysms of the aorta occur in about 35 people per 100,000 population, with rupture being the major complication. Ruptured abdominal aortic aneurysms are the tenth leading cause of death in men over 55 years old, resulting in 15,000 deaths per year in the United States.

High blood pressure and atherosclerosis are the major risk factors increasing the chances of the development of abdominal aneurysms. Other diseases commonly associated with abdominal aortic aneurysms are trauma, infection (syphilis), and connective tissue disorders (Marfan's syndrome and Ehlers-Danlos syndrome).

Abdominal aortic aneurysms are curable if detected early and before rupture occurs.

Abdominal aortic aneurysms often do not present with symptoms. Sometimes the diagnosis can be suspected on physical examination when a pulsatile mass is found over the mid abdomen. Usually when symptoms occur, it is due to the aneurysm compressing other structures such as the lower spine, leading to back pain. Abdominal discomfort, bright blood in the stools, or black tarry stools are other presenting symptoms that can occur with abdominal aneurysms.

An abdominal ultrasound is nearly 100% accurate in identifying an aneurysm and can estimate the size to within 0.3 to 0.4 cm. Computed tomography (CT) scan can estimate the size of the aneurysm to within 0.3 mm and can rule out rupture of the aneurysm if this is suspected.

Treatment of abdominal aortic aneurysms depends on the size of the aneurysm and the risk of rupture. The risk of rupture of an abdominal aortic aneurysm less than 4 cm is 2% in 5 years. The risk increases to 25% to 40% if the aneurysm is greater than 5 cm. Therefore, surgery to correct the aneurysm is generally recommended for patients having an aneurysm greater than 5 cm. For patients with aneurysms less than 4 cm, most physicians recommend follow-up examinations with ultrasound every 6 months to 1 year. For patients with aneurysms between 4 to 5 cm, this remains controversial. Some surgeons recommend surgery and others recommend follow-up examinations every 6 months with ultrasound to look for expansion. If there is a greater than 0.5-cm expansion in this group, most physicians recommend proceeding with surgery.

• Remember that the major complication of abdominal aortic aneurysm is rupture. It is estimated that 90% of the people whose aortas rupture do not survive. Of those patients who reach the hospital with a ruptured aneurysm, it is estimated that 50% will survive.
• Remember that if elective surgery is being planned to correct the abdominal aneurysm, you should see a cardiologist first to evaluate your cardiac status before having surgery. A detailed workup of the heart is indicated, since most complications of surgery result from underlying heart disease (e.g., heart attack, heart failure, and rhythm disturbances).

• Don't forget the numbers 4 cm and 5 cm. Most authorities recommend prophylactic surgery on patients with aneurysms greater than 5 cm. Most authorities recommend observation for patients with aneurysms less than 4 cm. The controversy lies in patients with aneurysms between 4 and 5 cm.

• If you know you have an abdominal aneurysm and develop new back pain or abdominal pain.
• If you need a referral to a cardiologist, a vascular surgeon, or both.
• If you have pain, fever, or drainage from the incision sites after surgery.
• If you have blood in the stool or black stools.

_______________________________________________________________________________________________________________________________
Copyright © 2000 Mosby, Inc.
All rights reserved.  No part of this publication may be reproduced or transmitted in any form or for any means, electronic or mechanical, including photocopy, recording, or any information storage and retrieval system, without permission in writing from the publisher.
_______________________________________________________________________________________________
For Comments/Suggestion send email to: webmaster@apma-nc.com