Aortic aneurysm & dissection

Question 1

Define an aneurysm

Define dissection

Answer 1

>150% dilatation of original diameter of artery.

True aneurysm: All layers dilate

False aneurysm: Collections of blood around a vessel wall (eg after trauma) communicating with the lumen [blood contained by surrounding tissue]

Dissection is a tear within the wall of a vessel (ie splitting the media)

Question 2

What is the pathophysiology of thoracic aortic dissection (TAD)?

Answer 2

• Blood splits the aortic media
• Dissection can unfold which can subsequently occlude branches of the aorta

Question 3

How does an TAD present? Why?

Answer 3

• Sudden tearing chest pain (+/- radiation to back) due to tearing of media
• Distally occlusions can cause;
  
  • Hemiplegia (carotid artery occlusion)
  • Unequal arm pulses/ BP
  • Acute limb ischaemia
  • Paraplegia (anterior spinal artery)
  • Anuria (renal artery)
• Proximal occlusions can cause;
  
  • Aortic incompetence (aortic regurg & hence symptoms of aortic regurg)
  • Inferior MI

Question 4

What are the types of TAD?

Answer 4

Type A - involving ascending aorta (irrespective of site of tear)

Type B - not involving ascending aorta

Question 5

What is the investigations for TAD?

Answer 5

• CXR: PA may show mediastinal widening (may not)
• ECG: normal, inferior MI
• Contrast CT chest/abdo
• CT/MR angiography
• Echo

Question 6

How would you manage TAD?

Answer 6

• Pain & BP [<100 using Labetalol]
• Type A - urgent cardiothoracic surgery
• Type B
  
  • Medical therapy
  • If occlusions - vascular surgery