Aortic Dissection

Question 1

Definition of Aortic Dissection

Answer 1

• Separation in the aortic wall intima causing blood flow into a new false channel composed of the inner and outer layers of the media.

Question 2

Aetiology of Aortic Dissection

Answer 2

• Intimal tear that extends into the media of the aortic wall.
• Cystic medial degeneration predisposes to intimal disruption and is characterised by elastin, collagen and smooth muscle breakdown in the lamina media.

Question 3

Signs and Symptoms of Aortic Dissection

Answer 3

• Signs/symptoms include features of Marfan’s syndrome, features of Ehlers-Danlos syndrome, chest pain, interscapular and lower pain, left/right BP differential, pulse deficit and a diastolic murmur.
• Risk factors include HTN, atherosclerotic aneurysmal disease, Marfan’s syndrome, Ehlers-Danlos syndrome, bicuspid aortic valve, smoking, coarctation, annulo-aortic ectasia and FHx of aortic aneurysm or dissection.

Question 4

Pathophysiology of Aortic Dissection

Answer 4

• An intimal tear followed by subsequent degeneration of the medial layer of the aortic wall.
• Blood then passes into the media, propagating distally and proximally and creating a false lumen.
• The false lumen can occlude flow through branches of the aorta including coronary, brachiocephalic, intercostal, visceral and renal, or iliac vessels.

Question 5

Investigation of Aortic Dissection

Answer 5

• ECG
  
  • ST segment depression or elevation
• CXR
  
  • Widened mediastinum
• Cardiac enzymes
  
  • Negative
• CT angiography
  
  • Intimal flap
• Renal function
  
  • Elevated creatinine and urea
• LFTs
  
  • Elevated AST and ALT
• Lactate
  
  • Elevated
• FBC
  
  • Usually normal

Question 6

DeBakey Classification of Aortic Dissection

Answer 6

• Type I – originates in the ascending aorta and propagates at least to the aortic arch. They are typically seen in patients under 65yrs and carry the highest mortality.
• Type II – confined to the ascending aorta. Classically in elderly patients with atherosclerotic disease and hypertension
• Type III – originates distal to the subclavian artery in the descending aorta. Further subdivided into IIIa which extends distally to the diaphragm and IIIb which extends beyond the diaphragm into the abdominal aorta.

Question 7

Stanford Classification of Aortic Dissection

Answer 7

• Group A – includes DeBakey Types I and II and involves the ascending aorta and can propagate to the aortic arch and descending aorta; the tear can originate anywhere along this path
• Group B – dissections do not involve the ascending aorta and include DeBakey Type III

Question 8

Management of Aortic Dissection

Answer 8

• Resuscitation
• Confirmation by immediate imaging (US, CT or MRI angiogram)
• Urgent vascular input and surgical repair
• Manage HTN with BBs
• Urgent surgical stenting or repair (time critical)