Overview of Aortic Dissection
Arteries are blood vessels that carry blood from the heart to the rest of the body. Aortic dissection occurs when the inner lining of the body's main artery (the aorta) tears or splits open, creating two channels of blood flow within the aorta.
In aortic dissection, one channel (called the true lumen) continues to follow the normal course and delivers blood and oxygen to other parts of the body. Increased blood flow through the second channel (called the false lumen) can cause the aortic wall to tear even further or rupture (break apart).
In other cases, blood in the false lumen does not flow (i.e., remains stagnant). When this occurs, increased pressure within the aorta can cause the blood vessel to enlarge (widen), affecting other branches of the aorta and eventually penetrating the aortic wall.
Aortic dissection is a rare condition that requires immediate medical treatment. Ruptures in the aortic wall usually are fatal. Approximately 33 percent of patients with untreated aortic dissection die in the first 24 hours; 50 percent die within 48 hours.
Types of Aortic Dissection
Two methods are used to classify aortic dissections. These methods include the Stanford classification method (more common) and the DeBakey classification.
Each type is grouped according to the location of the dissection. Three locations are considered: the aortic arch, the ascending aorta, and the descending aorta. The path of the aorta begins in the heart and moves upward (ascends) to the arch, where it curves and then heads downward (descends), carrying blood to the lower parts of the body. The descending aorta branches into the thoracic aorta (above the diaphragm) and the abdominal aorta (below the diaphragm).
The Stanford classification system has two types—Type A, which includes only the ascending aorta, and Type B, which includes all locations except the ascending aorta. Most aortic dissections occur at the beginning of the ascending aorta. Type A dissections are more common—and more serious—than Type B. Type A dissections often advance within the chest and Type B dissections often move down into the abdomen.
The DeBakey classification method uses three descriptive types. Type I includes the ascending aorta, the aortic arch, and the descending aorta. Type II involves only the ascending aorta and Type III involves only the descending aorta.
Incidence & Prevalence of Aortic Dissection
Aortic dissections can occur in anyone, but the condition is most common in men between the ages of 40 and 70. In fact, men are three times more likely to experience an aortic dissection than women.
According to the Vascular Disease Foundation, aortic dissection affects 2 out of every 10,000 people in the United States. African Americans are at higher risk for aortic dissection than Caucasians and Asian Americans are less likely.