Classification

Classification of aortic dissection is based on the anatomic involvement of the condition. There are two classification systems in use (1).

De Bakey (1965) - an older system primarily used for auditing the results of treatment, categorizes dissections based on the origin of the intimal tear and the extent of the dissection:

• type I:
  • tear originates in the ascending aorta
  • extends at least to the aortic arch and often beyond it distally
• type II:
  • tear originates in the ascending aorta
  • dissection is confined to the ascending aorta
• type III:
  • tear originates in the descending aorta
  • dissection confined to descending aorta either stopping above the diaphragm (IIIa) or extending below the diaphragm (IIIb)

Stanford system - a simpler and newer system which has therapeutic significance and divides dissections into 2 categories, those that involve the ascending aorta and those that do not:

• type A:
  • dissection involves the ascending aorta with or without extension into the descending aorta i.e. De Bakey types I and II
  • accounts for 66% of cases
• type B:
  • dissection confined to the descending aorta, beginning distal to the subclavian artery i.e. De Bakey type III
  • accounts for 34% of cases

Reference:

• (1) Thrumurthy SG et al. The diagnosis and management of aortic dissection. BMJ. 2011;344:d8290.
• (2) Hiratzka LF et al. 2010 ACCF/AHA/AATS/ACR/ASA/SCA/SCAI/SIR/STS/SVM guidelines for the diagnosis and management of patients with Thoracic Aortic Disease: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines, American Association for Thoracic Surgery, American College of Radiology, American Stroke Association, Society of Cardiovascular Anesthesiologists, Society for Cardiovascular Angiography and Interventions, Society of Interventional Radiology, Society of Thoracic Surgeons, and Society for Vascular Medicine. Circulation. 2010;121(13):e266-369