An aneurysm is an abnormal bulging or widening of an artery. Arteries are the blood vessels that carry oxygen-rich blood from the heart to different parts of the body. Aneurysms can occur in any artery, but most frequently involve the aorta, the largest artery in the body. The aorta originates at the heart and then travels upward in the chest toward the head (the ascending aorta), giving rise to the arteries that supply blood to the arms and head. It then makes a U-turn (the aortic arch) and heads downward in the chest (the descending aorta) and then into the abdomen (abdominal aorta) giving rise, along the way, to many arterial branches that feed the rest of the body. Aortic aneurysms in the chest are called thoracic aortic aneurysms, and those that occur below the diaphragm are referred to as abdominal aortic aneurysms. Aneurysms can be caused by arteriosclerosis, high blood pressure, injury, inherited conditions (i.e., Marfan syndrome), connective tissue disorders or infection.
Aortic aneurysms are potentially dangerous because of the risk of rupture (sudden bursting resulting in fatal bleeding) or dissection (tearing or shearing within the layers of the aortic wall). The risk of complications is directly related to the diameter of the aorta. The normal aorta measures about an inch in diameter. Small aneurysms generally pose no threat, but as the diameter increases beyond a certain level, so too, does the risk of rupture. Aneurysms are also associated with arteriosclerosis (hardening of the arteries or cholesterol and calcium buildup) and clot formation, both of which can increase the risk of stroke (brain damage) or embolus (traveling clot/debris) to an abdominal organ or the legs.
Unfortunately, most aortic aneurysms produce no symptoms until rupture or dissection occurs. These catastrophic events are marked by the sudden onset of severe, searing or tearing pain. This pain is located in the chest and/or upper back for thoracic aneurysms, and in the abdomen or lumbar area for abdominal aortic aneurysms. If there is to be a chance for survival, immediate help must be sought as soon as the severe pain appears. Occasionally, patients may experience a persistent, aching pain caused by an expanding aneurysm that is pressing on other organs. Given that most aneurysms are asymptomatic, early detection is key to proper management. The goal is to remove an aneurysm before it progresses to the rupture stage. Risk factors for aneurysm include:
The presence of risk factors should be brought to the attention of your primary care physician, as periodic physical examinations and screening chest X-rays are often valuable in the early detection of aneurysms. Additional testing such as CT scan, MRI, echocardiogram/ultrasound and cardiac catheterization may also be used.
Large aneurysms or those that produce symptoms are removed and replaced with a tube graft, a synthetic replacement generally made of Dacron. The procedure involves making an incision in the chest (median sternotomy or left thoracotomy), using the heart-lung machine, and in certain situations, a period of circulatory arrest where all blood flow is stopped and the body is kept at a low temperature to protect vital organs. When an aortic aneurysm is located near the aortic valve (ascending aortic or aortic root aneurysm), the aortic valve may need to be replaced in addition to treating the aneurysm. For some patients, however, the aortic valve can be conserved.
Thoracic aortic stent grafting is one of many advanced, endovascular (meaning 'within the blood vessel') treatments available to patients with various conditions who would better tolerate, or simply prefer, a less invasive option over traditional, open surgery. Approved by the Food and Drug Administration (FDA) in 2005, this technology has revolutionized the treatment of older patients with thoracic aortic disease. The procedure involves attaching a self-expandable "stent graft" (a flexible tube reinforced inside with a self-expandable "scaffolding") to the end of a thin tube (catheter) and inserting it into the bloodstream, usually through an artery in the groin or leg. A small incision is typically all that is necessary. Using X-ray guidance, the surgeon threads the catheter through the aorta to the area of the aneurysm. Once expanded, the stent graft reinforces the weakened section of the aorta and bridges the blood supply away from the aneurysm, preventing further growth. Excluded from the blood supply, the aneurysm gradually shrinks.