Aortic Dissection, Thoracic



  • Aortic dissection begins when there is an intimal tear
  • Blood then dissects through the media under aortic systolic pressure
  • It is thought that hypertension is a major factor in the dissection process
  • Dissections can start proximally at the root and dissect distally to involve any or all branches of the aorta, such as the carotid and subclavian arteries
  • The dissection process can also proceed proximally to involve the aortic root, the coronary ostia, and the pericardium
  • Dissection that progresses proximally may lead to occlusion of the coronary ostia, aortic valve incompetence, or cardiac tamponade
  • Classification related to portion of aorta involved:
    • Stanford classification:
      • Type A: Ascending aorta
      • Type B: Distal to ascending aorta
    • DeBakey classification:
      • DeBakey I: Intimal tear in aortic arch or root
      • DeBakey II: Ascending aorta
      • DeBakey III: Distal to takeoff of left subclavian artery
  • Peak age for occurrence:
    • Proximal dissection: 50–55 yr
    • Distal dissection: 60–70 yr

Pregnancy Considerations
Risk of dissection increases in the presence of pregnancy:
  • In women <40 yr of age, 50% of dissections occur during pregnancy


Any process that affects the mechanical properties of the aortic wall can lead to dissection:
  • Hypertension (72% of patients in the Registry of Acute Aortic Dissection)
  • Congenital heart disease (bicuspid aortic valve, coarctation)
  • Aortic wall connective tissue abnormalities (cystic medial necrosis)
  • Connective tissue disease (Marfan disease, Ehlers–Danlos syndrome)
  • Pregnancy
  • Infectious/inflammatory conditions that can cause vasculitis (lupus, syphilis, endocarditis, giant cell arteritis, rheumatoid arthritis, Takayasu arteritis)
  • Previous cardiac surgery including CABG, aortic valve repair
  • Tobacco use

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