Description

• Aortic dissection begins when there is an intimal tear
• Blood dissects through the media, creating a false lumen under aortic systolic pressure
• Hypertension is thought to be 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 past the takeoff of the innominate artery
  • DeBakey classification:
    • DeBakey I: Involves aortic root and arch, can extend further
    • DeBakey II: Ascending aorta only
    • DeBakey III: Distal to takeoff of left subclavian artery
• Peak age for occurrence:
  • Proximal dissection: 50–55 yr
  • Distal dissection: 60–70 yr

Etiology

Any process affecting 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, penetrating atherosclerotic ulcer)
• Connective tissue disease (Marfan disease, Ehlers–Danlos syndrome, Turner syndrome)
• Pregnancy
• Infectious/inflammatory conditions that can cause vasculitis (lupus, syphilis, endocarditis, giant cell arteritis, rheumatoid arthritis, Takayasu arteritis)
• Prior cardiac surgery (CABG, AVR)
• Tobacco use, cocaine use
• Iatrogenic: Cardiac catheterization, arterial cannulation, aortic cross clamping, IABP
• Trauma