Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.
An aortic aneurysm develops from a weakness in the wall of the aorta. This weakness can be present at birth or can develop as the result of disease or injury.
Atherosclerosis: A clogged or damaged artery from a condition called atherosclerosis is the most common cause of aneurysm. Atherosclerosis is often called hardening of the arteries because it calcifies later in life. In atherosclerosis, a fatty substance (cholesterol) called plaque sticks to the lining of the blood vessel wall, weakening the wall. Atherosclerosis is also the most common cause of heart disease and heart attack.
High blood pressure: High blood pressure puts stress on the wall of the aorta. Over many years, this stress can lead to bulging of the blood vessel wall. This is the leading factor in development of aneurysms of the thoracic aorta.
Diabetes: Uncontrolled diabetes damages blood vessels by premature, accelerated atherosclerosis, leaving them vulnerable to a number of conditions including aneurysm formation.
Cystic medial necrosis: In this condition, the medial layer of the blood vessel wall degenerates, and an abnormal fibrous layer weakens the supporting structure of the blood vessel wall itself. This commonly occurs with certain rare inherited conditions such as Marfan syndrome and Ehlers-Danlos syndrome. It also occurs with heart valve disease and pregnancy.
Mycotic aneurysm occurs when bacteria spread into the arterial system, invade the blood vessel wall, and weaken the vessel. Often the bacteria enter areas of previous damage or areas weakened since birth. Although rare today, the advanced form of the sexually transmitted disease syphilis was a common cause of this condition in the early part of the 20th century.
Inflammatory aneurysm: Inflammatory conditions or vasculitis, such as psoriasis and rheumatoid arthritis, may produce inflammation in the blood vessel wall itself. If the inflammation is not reversed, it eventually weakens the wall of the aorta. Vasculitis generally affects the smaller to medium-sized vessels and rarely the aorta.
Injury: Injury to the chest or abdomen, as in a car wreck or bad fall, can damage an area of the aorta. This leaves the aorta vulnerable to bulging.
In many cases, the cause of an aortic aneurysm is never known.
Risk factors for aortic aneurysm include the following:
Abdominal aortic aneurysms (AAAs) represent a degenerative process of the abdominal aorta that is often attributed to atherosclerosis; however, the exact cause is not known. A familiar clustering of AAAs has been noted in 15-25% of patients undergoing repair of the problem.