Aortic Dissection

Question 1

Define Aortic Dissection

Answer 1

An aortic dissection is a tear in the intimal layer of the aorta that extends into the media which causes blood to flow into a new false channel composed of the inner and outer layers of the media. This results in a progressively growing hematoma in the intima-media space.

Question 2

Aetiology/Risk Factors for Aortic Dissection

Answer 2

• Hypertension (most common risk factor)
• Syphilitic aortitis
• Smoking
• Marfan syndrome/Ehlers-Danlos syndrome
• Bicuspid aortic valve
• Coarctation of the aorta
• Use of amphetamines and cocaine

Question 3

Epidemiology

Answer 3

• Men
• Over 50 years

Question 4

Presenting symptoms of Aortic Dissection

Answer 4

• Sudden and severe tearing/ripping pain
  
  • Anterior chest (ascending - most common dissection site - 65%) or back (descending)
  • Anterior chest pain radiates to the back/interscapular region as the dissection spreads
• Syncope, diaphoresis

Question 5

Signs on Physical Examination

Answer 5

• Hypertension
• Asymmetrical blood pressure and pulse readings between limbs
• A diastolic decrescendo heart murmur (an aortic regurgitation in a proximal dissection)
• Marfanoid body habitus:
  
  • Tall stature
  • Arachnodactyly (long fingers and toes)
  • Long arm span
  • High arched palate
  • Pectus axcavatum/carinatum
  • Hypermobile joints
• Ehler-Danlos
  
  • Translucent skin
  • Very stretchy
  • Hypermobile joints

Question 6

Investigations

Answer 6

• 1st: ECG & Cardiac Enzymes to exclude MI
• Chest X-Ray: Shows widened mediastinum and loss of aortic knucle
• Group & Save, Cross-match
• contrast CT Angiography: This is a gold-standard, diagnostic test
  
  • Should be ordered as soon as diagnosis suspected. Should include chest, abdomen, and pelvis to visualise extent of the dissection
  • If patient is shocked/unresponsive consider a TO Echocardiogram
  • TOE has an advantage in being portable and able to be performed at the bedside for the unstable patient, no contrast used and better resolution than TTE

Question 7

Classifications of Aortic DIssections

Answer 7

STANFORD

Stanford type A aortic dissection: any dissection involving the _A_scending aorta with or without involvement of descending aorta

• defined as proximal to the brachiocephalic artery
• Can extend proximally to the aortic arch and distally to the descending aorta
• requires SURGICAL AND Medical management
• IV Labetalol and TEVAR (thoracic endovascular aortic repair) OR open repair
• Complications include aortic regurgitation, coronary artery involvement and cardiac tamponade.

Stanford type B aortic dissection: any dissection not involving the ascending aorta

• Descending aorta; originating distal to the left subclavian artery
• Requires Medical management e.g. beta blockers (Labetalol for BP control), vasodilators
• Only requires surgery if affects aortic branches (e.e. renal arteries causing renal ischaemia)

DeBAKEY

• Type I
  
  • Dissections originate in the ascending aorta and continue to at least the aortic arch but typically as far as the descending aorta.
• Type II
  
  • Dissections originate in, and are restricted to, the ascending aorta.
• Type III
  
  • Dissections originate in the descending aorta and most often extend distally.