When it leaves the heart, the aorta first moves up through the chest toward the head (the ascending aorta). It then bends or arches, and finally moves down through the chest and abdomen (the descending aorta).
Aortic dissection most often happens because of a tear or damage to the inner wall of the aorta. This usually occurs in the chest (thoracic) part of the artery, but it may also occur in the abdominal part.
When a tear occurs, it creates two channels:
- One in which blood continues to travel
- Another where blood stays still
If the channel with nontraveling blood gets bigger, it can push on other branches of the aorta. This can narrow the other branches and reduce blood flow through them.
An aortic dissection may also cause abnormal widening or ballooning of the aorta (aneurysm).
The exact cause is unknown, but more common risks include:
- Blunt trauma to the chest, such as hitting the steering wheel of a car during an accident
- High blood pressure
Other risk factors and conditions associated with the development of aortic dissection include:
- Bicuspid aortic valve
- Coarctation (narrowing) of the aorta
- Connective tissue disorders
- Heart surgery or procedures
- Marfan syndrome and rare genetic disorders
- Swelling of the blood vessels due to conditions such as arteritis and syphilis
Aortic dissection occurs in about 2 out of every 10,000 people. It can affect anyone, but is most often seen in men ages 40 to 70.