The exact causes of thoracic aortic aneurysms are unknown, but factors that can contribute to an aneurysm's development include:

  • Hardening of the arteries (atherosclerosis). As plaque builds up on your artery walls, they become less flexible, and the additional pressure can cause them to weaken and bulge. High blood pressure and high cholesterol are risk factors for hardening of the arteries.
  • Connective tissue diseases. People who are born with Marfan syndrome, a genetic condition that affects the connective tissue in the body, are particularly at risk of a thoracic aortic aneurysm. Those with Marfan syndrome may have a weakness in the aortic wall that makes them more susceptible to aneurysm. People with Marfan syndrome often have distinct physical traits, including tall stature, very long arms, a deformed breastbone and eye problems.

    Besides Marfan syndrome, other connective tissue diseases, such as Ehlers-Danlos and Loeys-Dietz syndromes, can contribute to a thoracic aortic aneurysm. Ehlers-Danlos syndrome causes your skin, joints and connective tissue to be fragile and makes your skin stretch easily.

  • Other medical conditions. Inflammatory conditions, such as giant cell arteritis and Takayasu's arteritis, may cause thoracic aortic aneurysms.
  • Problems with your heart's valves. Sometimes people who have problems with the valve that blood flows through as it leaves your heart (aortic valve), have an increased risk of thoracic aortic aneurysm. This is especially true for people who have a bicuspid aortic valve, meaning their aortic valve has only two leaflets instead of three.
  • Untreated infections. Though not a common cause of thoracic aortic aneurysm, you're more likely to develop this condition if you've had an untreated infection, such as syphilis or salmonella.
  • Traumatic injury. Some people who are injured in falls or motor vehicle crashes develop thoracic aortic aneurysms.

An aortic aneurysm is different from an aortic dissection. Aortic dissection can occur in the same place many aneurysms occur. In aortic dissection, a tear occurs in the wall of the aorta. This causes bleeding into and along the aortic wall and, in some cases, completely outside the aorta (rupture). Aortic dissection is a life-threatening emergency.

Jul. 29, 2014

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