Aortic dissection is a tear between the inner and outer layers of the aortic wall. The tear can cause the wall to separate and rupture, resulting in life-threatening bleeding and death.

The aorta, like all arteries, is made up of three layers, which are fused together. If the layers begin to separate, it causes bleeding into and around the tear. The bleeding widens the tear and causes the layers to separate. Typically, an aortic dissection occurs in the section of the aorta that leaves the heart and curves down through the chest.

Aortic dissection can be caused by atherosclerosis (hardening of the arteries) and high blood pressure; traumatic injury to the chest, such as hitting the car steering wheel during an accident; and conditions that are present at birth, such as Marfan's syndrome or Ehlers-Danlos syndrome.

Symptoms usually include sudden and severe chest or upper back pain, anxiety, pallor, sweating, and nausea. Aortic dissection usually requires emergency surgery to repair the tear.