Aortic dissection

Question 1

Define aortic dissection

Answer 1

DEFINITION: a condition where a tear in the aortic intima allows blood to surge into the aortic wall, causing a split between the inner and outer tunica media, creating a false lumen

Question 2

Classify aortic dissection

Answer 2

Type A: ASCENDING aorta (MOST COMMON)

Type B: DESCENDING aorta (distal to the left subclavian artery)

Question 3

Explain the aetiology/risk factors of aortic dissection.

Answer 3

Aortic dissection is usually preceded by degenerative changes in the smooth muscle of the aortic media

Common causes and risk factors:
HYPERTENSION
Aortic atherosclerosis
Connective tissue disease (e.g. Marfan’s, Ehlers-Danlos, SLE)
Congenital cardiac abnormalities (e.g. coarctation of the aorta)
Aortitis
Iatrogenic (e.g. during angioplasty/angiography)
Trauma
Crack cocaine

NOTE: expansion of the false lumen can lead to obstruction of the subclavian, carotid, coeliac and renal arteries

Hypoperfusion of the target organs of these major arteries can give rise to other symptoms

Question 4

Summarise the epidemiology of aortic dissection

Answer 4

mainly men age 40-60

Question 5

Recognise the presenting symptoms of aortic dissection

Answer 5

MAIN SYMPTOM: sudden central ‘tearing’ pain, it may radiate to the back in between the shoulder blades (it can mimic MI)

Other symptoms caused by obstruction of branches of the aorta:

Carotid artery –> hemiparesis, dysphasia, blackout

Coronary artery –> chest pain (angina or MI)

Subclavian artery –> ataxia, loss of consciousness

Anterior spinal artery –> paraplegia

Coeliac axis –> severe abdominal pain (due to ischaemic bowel)

Renal artery –> anuria, renal failure

Question 6

Recognise the signs of aortic dissection on physical examination

Answer 6

Murmur on the back (below the left scapula), descending to the abdomen

Hypertension

Blood pressure difference between the two arms > 20 mm Hg

Wide pulse pressure

Hypotension may suggest tamponade

Check for pulsus paradoxus = abnormally large decrease in systolic blood pressure and pulse wave amplitude during inspiration

This may indicate: 
Tamponade 
Pericarditis 
Chronic sleep apnoea 
Obstructive lung disease

Question 7

Identify 6 appropriate investigations for aortic dissection?

What would they show?

Answer 7

1. Bloods;
FBC 
X-match 10 units of blood  
U&E - check renal function  
Clotting screen 

2. CXR; Widened mediastinum
3. ECG; Often NORMAL
   If the ostia of the right coronary artery is compromised you may get signs of:
   Left ventricular hypertrophy
   Inferior MI
4. CT Thorax; Shows false lumen
5. Echocardiography
   Transoesophageal allows visualisation
6. Cardiac catheterisation and aortography