Aortic dissection - vascular

Question 1

What is an aortic dissection?

Answer 1

Tear in intima

–> blood to surge into aortic wall

–> split between inner & outer tunica media

–> creating a false lumen

Question 2

What are the classifications of an aortic dissection?

Answer 2

• Type A involving the ascending (±descending) aorta;
• type B involving only the descending aorta

De Bakey classification

• Type I: proximal tear, with dissection involving the ascending and descending aorta
• Type II: ascending aorta only
• Type III: descending aorta only

Question 3

What is the process of aortic dissection?

Answer 3

Question 4

What are the causes of aortic dissection?

Answer 4

conditions that –> degeneration of SM of aortic media

cystic medial degeneration

• elastin, collagen, smooth muscle breakdown in lamina media.

ruptured vasa vasorum

• ​see image

Marfan’s syndrome & Ehler Danlos syndrome (connective tissue disease)

• –> weakening of media –> predisposed to dilation + dissection

Hypertension

Aortic Atherosclerosis

Congenital cardiac abnormalities

• coarctation

Aortitis

• Takayasu’s aortitis, tertiary syphilis

Iatrogenic

• during angioplasty, angiography

Trauma

Cocaine

Question 5

What are the risk factors for aortic dissection?

Answer 5

• hypertension
• Marfan syndrome, Ehlers-Danlos syndrome
• bicuspid aortic valve
• annulo-aortic ectasia
  
  • dilation of proximal ascending aorta + aortic annulus (=fibrous ring marking separtation of the aorta from right ventricle)
• coarctation
• smoking
• family history of aortic aneurysm / dissection

Question 6

Summarise the epidemiology of aortic dissection

Answer 6

• males > females
• 50+ yrs

Question 7

What are the presenting symptoms of aortic dissection?

Answer 7

• Sudden, central tearing chest pain
  
  • ± radiation to back
• ~ –> occlusion of aorta + its branches:
  
  • ​see image

Question 8

What are the signs of aortic dissection on physical examination?

Answer 8

• Murmur on back
  
  • ​below L scapula, descending to abdomen
• HTN
  
  • ​BP discrepancy between arms of >20mmHg
• Aortic insufficiency
  
  • ​collapsing pulse, early diastolic murmur over aortic area, unequal
• arm pulses
• ± palpable abdominal mass

Question 9

What are the primary investigations for a suspected aortic dissection?

Answer 9

• ECG
• Chest x ray
  
  • excludes pulmonary causes of chest pain
• CT angiography
  
  • diagnostic

bloods:

• FBC
• cardiac enzymes
  
  • excludes MI
• serum creatinine
  
  • high = renal function impaired
• serum urea
  
  • high = renal function impaired
• aspartate transaminase
  
  • high = liver functional impaired
• ​alanine transaminase
  
  • ​high = liver functional impaired
• Serum lactate
• type & cross

Question 10

What are the secondary investigations to consider for a suspected aortic dissection?

Answer 10

• D-dimer i.e. fibrin degradation product (FDP)
  
  • if +tive, little clinical meaning ; if -tive definitely not an aortic dissection
• trans-oesophagael ECG > trans-thoracic (sens + spec)
  
  • intimal flap seen
• MR angiography
  
  • rarely used in acute setting - hard to obtain
• Intravascular US
• Smooth muscle myosin heavy chain protein
  
  • ​released from damaged medial aortic SM