Aortic Dissection

Question 1

Definition

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

Classification

Answer 2

o Type A: ASCENDING aorta (MOST COMMON)

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

Question 3

Aetiology/risk factors

Answer 3

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

Question 4

Before

Answer 4

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

Question 5

After

Answer 5

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 6

Epidemiology

Answer 6

Most common in males aged 40-60 yrs

Question 7

Presenting symptoms (main symptom)

Answer 7

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

Question 8

Presenting symptoms (other symptoms)

Answer 8

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 9

Signs on physical examination

Answer 9

· 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 10

Investigations (bloods)

Answer 10

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

Question 11

Investigations (other)

Answer 11

· CXR
o Widened mediastinum

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

· CT Thorax
o Shows false lumen

· Echocardiography
o Transoesophageal allows visualisation

· Cardiac catheterisation and aortography