Aortic Dissection, Thoracic

Description

• 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

• In women <40 yr of age, 50% of dissections occur during pregnancy

Etiology

• 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