Aortic Dissection

Life-threatening vascular emergency due to tear of the aortic intima, allowing entry of blood between the intima and media leading to creation of a false lumen that extends under pressure, leading to organ ischaemia due to occlusion of the true lumen.

The Standford Classification divides aortic dissections on their anatomical origin, and determines the management:

• Type A
  Originate in the ascending aorta.
  • Mortality of 1-2% per hour after onset
• Type B
  Originate in the descending aorta, but may propagate proximally.
  • May be medically managed
    Control of HR and BP.

The DeBakey Classification divides based on anatomical origin and extent, but is less helpful than the Stanford classification for the non-interventionalist as it is more verbose and doesn’t further influence management:

• Type I
  • Begins in the ascending aorta
  • Extends past the aortic arch
    May extend to the iliacs.
• Type II
  • Begins in the ascending aorta
  • Ends in the ascending aorta
• Type III
  Subdivided into:
  • IIIa
    • Begin distal to the L SCA
    • Does not extend past the diaphgram
  • IIIb
    • Begin distal to the L SCA
    • Extend past the diaphragm

Epidemiology and Risk Factors

Key risk factors:

• Age
• CVS disease
  • Hypertension
    Poorly controlled or situational.
  • Hyperlipidaemia
  • Smoking
• Cocaine use
• Genetics
• Pregnancy
  Generally 3^rd trimester or post-partum.

Pathophysiology

Aetiology

May be:

• Degenerative
• Genetic disease
  Diseases of connective tissue:
  • Marfans Syndrome
  • Ehlers-Danlos Syndrome
  • Familial Aortic Dissection
  • Annuloaortic ectasia
• Iatrogenic
  • Cardiac surgery
  • Cardiac catheterisation
  • IABP insertion

Clinical Manifestations

Presentations include:

• Chest and back pain
  Rapid onset, severe.
• May be painless in 6%
  Generally:
  • Diabetic
  • History of AAA
  • History of cardiac surgery
• Cardiac failure
• CVA
• Syncope

Diagnostic Approach and DDx

Investigations

Include:

• CT
• TOE

Management

Resuscitation:

• C
  • Haemodynamic control
    Vital to reduce progression of dissection, though urgency is ↑ in type A. Targets:
    • SBP 100-120mmHg
      • Labetalol
      • Magnesium
      • GTN
    • HR ⩽60bpm
      • Labetalol
      • Metoprolol
  • Arterial access to guide resuscitation
• D
  • Analgesia
    For control of haemodynamics.
    • Fentanyl

Specific therapy:

• Pharmacological
• Procedural
• Physical

Supportive care:

Disposition:

• OR
  Urgent theatre for Type A dissections.
• ICU/
  Often required for BP control.

Anaesthetic Considerations

Marginal and Ineffective Therapies

Complications

Prognosis

Key Studies

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References