Aortic dissection

Question 1

Define

Answer 1

• 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
• Medical emergency

Question 2

What are the two types?

Answer 2

o Type A: ASCENDING aorta (MOST COMMON)

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

Question 3

What’s the aetiology?

Answer 3

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

Question 4

What are the risk factors?

Answer 4

• Common causes and risk factors:
o HYPERTENSION
o Aortic atherosclerosis
o Connective tissue disease (e.g. Marfan’s, Ehlers-Danlos, SLE)
o Congenital cardiac abnormalities (e.g. coarctation of the aorta)
o Aortitis
o Iatrogenic (e.g. during angioplasty/angiography)
o Trauma
o Crack cocaine
• NOTE: expansion of the false lumen can lead to obstruction of the subclavian, carotid, coeliac and renal arteries
o Hypoperfusion of the target organs of these major arteries can give rise to other symptoms (e.g. carotid artery –> collapse)

Question 5

Epidemiology?

Answer 5

• Most common in males aged 40-60 yrs

Question 6

What are the presenting symptoms?

Answer 6

• 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:
o Carotid artery –> hemiparesis, dysphasia, blackout
o Coronary artery –> chest pain (angina or MI)
o Subclavian artery –> ataxia, loss of consciousness
o Anterior spinal artery –> paraplegia
o Coeliac axis –> severe abdominal pain (due to ischaemic bowel)
o Renal artery –> anuria, renal failure

Question 7

What are the signs?

Answer 7

•	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 
o	Check for pulsus paradoxus = abnormally large decrease in systolic blood pressure and pulse wave amplitude during inspiration
o	This may indicate:
•	Tamponade
•	Pericarditis
•	Chronic sleep apnoea
•	Obstructive lung disease 
•	Signs of Aortic Regurgitation
o	High volume collapsing pulse 
o	Early diastolic murmur over aortic area 
•	Unequal arm pulses 
•	There may be a palpable abdominal mass

Question 8

What are the appropriate investigations?

Answer 8

•	Bloods
o	FBC
o	X-match 10 units of blood (prep for surgery)
o	U&E - check renal function 
o	Creatinine – check renal function
o	Clotting screen
o	Cardiac enzymes
•	CXR

o Widened mediastinum
• ECG
o Often NORMAL
o ST depression may occur with acute dissection
o If the ostia of the right coronary artery is compromised you may get signs of:
• Left ventricular hypertrophy
• Inferior MI

• CT Thorax, abdomen and pelvis

o	Shows false lumen
o	show extent of aneurysm
•	Echocardiography
o	Transoesophageal allows visualisation 
•	Cardiac catheterisation and aortography