Aortic dissection

Question 1

Define 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

Type A: ASCENDING aorta (MOST COMMON)
Type B: DESCENDING aorta (distal to the left subclavian artery

Question 2

Explain the aetiology/risk factors of aortic dissection

Answer 2

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

Question 3

Summarise the epidemiology of aortic dissection

Answer 3

Most common in males aged 40-60 yr

Question 4

Recognise the presenting symptoms of aortic dissection

Answer 4

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 5

Recognise the signs of aortic dissection on physical examination

Answer 5

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

Unequal arm pulses

There may be a palpable abdominal mass

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

Question 6

Identify appropriate investigations for aortic dissection

Answer 6

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

CXR - Widened mediastinum

ECG - Often NORMAL
If the ostia of the right coronary artery is compromised you may get signs of: Left ventricular hypertrophy, Inferior MI

CT Thorax - Shows false lumen

Echocardiography - Transoesophageal allows visualisation

Cardiac catheterisation and aortography