Aortic aneurysms develop after weakening of the arterial walls causes a bulging of the artery. Weakening of the arterial walls can be caused by birth defects, or can develop over time, either from injury or illness. Atherosclerosis, the collection of plaque along the arterial walls, is the most common cause of aneurysms. As plaque collects, it reduces the available space for blood to travel, which increases the pressure and causes strain on the arterial walls. The exact cause of atherosclerosis is unknown, but it appears to develop in all humans over time. However, conditions such as high blood pressure and diabetes, or diets rich in LDL cholesterol can increase the rate of plaque formation.
In addition to increasing the rate of atherosclerosis, high blood pressure causes more strain on the arterial walls, increasing the risk of aneurysms' formation. Over time, the arterial walls will begin to weaken in response to constant stress, and form bulging. Aneurysms of the thoracic aorta are most common in individuals with high blood pressure.
Aneurysms can also be caused by cystic medial necrosis, a condition where the medial layer of the artery degrades and the vessel wall is weakened by an abnormal fibrous layer. This condition typically occurs with Marfan’s syndrome, Ehlers-Danlos syndrome, heart valve disease, and during pregnancies. Another condition, mycotic aneurysms, can develop as the result of bacterial infection in the arterial system. Typically, the sites of damage have been weakened since birth, and infection will cause further weakening of the arterial tissue. Injury to the chest or abdomen can damage the aorta, which can cause weakening, leading to the development of aneurysms.
Treatment of aortic aneurysms depends on the location, size, and progression of the aneurysms. For aneurysms with a low risk of rupture, the site of the aneurysms is typically monitored over a five year period. The aneurysms are monitored using Ultrasound/ CT every six to twelve months. Aneurysms which exceed 5.5 cm are typically treated through surgical procedures. The risk of surgical procedure is high, and varies depending on the severity of the aneurysm.