Aneurysms can affect the thoracic aorta in isolation (thoracic aortic aneursysm [TAA]) or can extend into the abdominal aorta (thoracoabdominal aortic aneurysms [TAAA]).

Thoracic Aortic Aneursym

The most common location for TAAs is the descending thoracic aorta. Where the ascending aorta or aortic arch is involved, this is the domain of the cardiothoracic surgeon. TAAs in the descending aorta are classified into:

• Type A: Upper half (above sixth intercostal space)
  
• Type B: Lower half (below sixth intercostal space)
  
• Type C: Entire descending TAA.

Aetiology

Risk factors of smoking, hypertension and hypercholesterolaemia, but also particularly related to:

• connective tissue disorders (e.g. Marfan’s, Ehlers-Danlos).
  
• syphilis (rare now).
  
• chronic dissections.
  
• infection.