Aortic dissection

Aortic dissection, abbreviated AoD, is an uncommon condition with a relatively high mortality.

General

Risk factors:

• Hypertension.
• Atherosclerosis.
  • Smoking.
• Cardiac surgery - rare, well-known complication.
  • In one large registry, approximately 15% of acute dissections are associated with prior cardiac surgery.

Note:

• Diabetes uncommon in thoracic aortic dissection.

May be separated into two groups:

1. Hypertension + atherosclerosis, typically 40-60 years old.
2. Connective tissue disorders - "young".

Associations

Heritable:

• Marfan's syndrome.
• Loeys-Dietz syndrome - a Marfan-like syndrome
• Ehlers-Danlos syndrome.
• Bicuspid aortic valve.

Others:

• Tertiary syphilis.
• Turner syndrome.

Classification

Two classification exist:

• DeBakey.
• Stanford.

Stanford dissection classification:

• Type A - aortic root to the left subclavian artery.
  • Considered a surgical emergency.
• Type B - distal to (left) subclavian artery.
  • Generally, treated conservatively.

Gross

• Entry intimal tear +/- exit intimal tear.
  • Blood between layers of the vessel wall.

Images

• 

  Aortic dissection. (WC)

www:

• Aortic dissection (utah.edu).
• Aortic dissection (brown.edu).

Microscopic

Features:

• Defect in the tunica media (muscle layer).
• "Abundant" fresh blood in the adventitia.
• +/-Changes of cystic medial degeneration - a specific histopathologic cause of aortic dissection.

DDx:

• Cystic medial degeneration.

Images

• 

  Aortic dissection. Victoria blue-H&E. (WC/KGH)

www:

• Aortic dissection - autopsy (upmc.edu).
• Aortic dissection (utah.edu).

Stains

• Alcian blue-PAS - no ground substance - see cystic medial degeneration.
• Elastin stain - no extensive fragmentation of the elastin fibres.

Sign out

PORTION OF AORTA, EXCISION/REPAIR:
- AORTIC WALL WITH EVIDENCE OF DISSECTION.
- NO SIGNIFICANT INFLAMMATION.
- NO MICROORGANISMS IDENTIFIED WITH ROUTINE STAINS.
- NO EVIDENCE OF CYSTIC MEDIAL DEGENERATION, SEE COMMENT.

COMMENT:
An elastic staining does not demonstrate fragmentation of the elastin fibres. No
degenerative changes of the media are apparent with Alcian blue-PAS staining.

See also

• Vascular disease.