Aortic Dissection

Question 1

What is the definition of an aortic dissection?

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

Question 2

How are aortic dissections classified?

Answer 2

Type A: ASCENDING aorta (MOST COMMON)

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

Question 3

What is the aetiology of aortic dissections?

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 (e.g. carotid artery –> collapse)

Question 4

What is the epidemiology of aortic dissection?

Answer 4

Most common in males aged 40-60 yrs

Question 5

What are 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

What are the signs of aortic dissection upon 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

Signs of Aortic Regurgitation

• > High volume collapsing pulse
• > Early diastolic murmur over aortic area

Unequal arm pulses

There may be a palpable abdominal mass

Question 7

What are the appropriate investigations for aortic dissection?

Answer 7

Bloods

• FBC
• X-match 10 units of blood
• U&E - check renal function
• Clotting screen

CXR = widened mediastinum

ECG:

• Often normal
• If ostia of the right coronary artery is compromised you may get signs of: Left ventricular hypertrophy or Inferior MI

CT Thorax = Shows false lumen

Echocardiogram = Transoesophageal allows visualisation

Cardiac catheterisation and aortography