Aortic dissection (CV)

Question 1

Define aortic dissection.

Answer 1

• tear in aortic wall intima causing blood to flow into a new false lumen in the intima-media space
• this can cause a haematoma to form and rupture –> occlusion of vessels

Question 2

Which groups does aortic dissection usually affect? (3)

Answer 2

• M>F
• 60-80 years old
• patients with Marfan syndrome (or other CTDs) are 30-50y/o and predisposed to aortic dissection and aneurysms

Question 3

Which part of the aorta is usually affected in aortic dissection?

Answer 3

Most commonly the ascending aorta (Stanford type A)

Question 4

What is aortic dissection usually preceded by?

Answer 4

Degenerative changes in smooth muscle of aortic media

Question 5

What can expansion of the false lumen in aortic dissection lead to?

Answer 5

Obstruction of branches of aorta (subclavian, carotid, coeliac, renal arteries) –> hypoperfusion of the target organs of these major arteries –> other symptoms

Question 6

What are the two classification methods used for aortic dissection?

Answer 6

• Stanford classification
• DeBakey classification

Question 7

Describe the Stanford classification for aortic dissection.

Answer 7

• Stanford type A (2/3) - dissection involving the ascending aorta (with/without involvement of arch and descending aorta)
• Stanford type B (1/3) - dissection involving the descending aorta only (distal to left subclavian artery)

Question 8

Describe the DeBakey classification for aortic dissection.

Answer 8

• type I - involves ascending and descending aorta (originates ascending –> at least aortic arch and possibly beyond distally)
• type II - only ascending aorta up to brachiocephalic artery (originates in and confined to ascending)
• type III - only descending aorta distal to left subclavian artery (originates descending, rarely extends proximally but will extend distally)

Question 9

What are some clinical features of aortic dissection? (5)

Answer 9

• sudden and severe, sharp tearing chest pain
• intercapsular pain radiating to the back (back/abdominal pain may be type B)
• asymmetrical BP and pulse between limbs (mostly arms)
• early diastolic murmur (aortic regurgitation) in ascending aortic dissection (severe AR = Austin flint murmur which is mid-diastolic best heard at apex)
• focal neurological deficits (Horner’s syndrome in carotid dissection)

Question 10

What are some specific features of asymmetrical BP and pulse between limbs in aortic dissection? (3)

Answer 10

• weak or absent carotid, brachial or femoral pulse
• radio-radial delay
• radio-femoral delay

Question 11

What specific symptoms are caused by obstruction of aorta branches in aortic dissection? (6)

Answer 11

• carotid artery - hemiparesis, dysphasia, blackout
• coronary artery - chest pain (angina/MI)
• subclavian artery - ataxia, loss of consciousness
• anterior spinal injury - paraplegia
• coeliac axis - severe abdominal pain due to ischaemic bowel
• renal artery - anuria, renal failure

Question 12

What is an Austin flint murmur?

Answer 12

Mid-diastolic murmur best heard at apex, sign of severe aortic regurgitation

Question 13

What focal neurological deficit is seen in carotid dissection?

Answer 13

Horner’s syndrome - due to compression of the sympathetic trunk by expanding aortic dissection

Question 14

What might you see on examination of aortic dissection? (9)

Answer 14

• murmur on back (below left scapula) descending to abdomen
• Horner’s syndrome
• hypertension
• BP difference >20mmHg between two arms
• unequal arm pulses
• wide pulse pressure
• signs of aortic regurgitation - high volume collapsing pulse, early diastolic murmur over aortic area
• palpable abdominal mass
• pulsus paradoxus - abnormally large decrease in systolic BP and pulse wave amplitude during inspiration

Question 15

What might pulsus paradoxus indicate? (4)

Answer 15

• tamponade (hypotension)
• pericarditis
• chronic sleep apnoea
• obstructive lung disease

Question 16

What is the most important risk factor for aortic dissection?

Answer 16

Hypertension

Question 17

What are some risk factors for aortic dissection?

Answer 17

• hypertension
• trauma
• CTDs e.g. Marfan’s syndrome, Ehlers-Danlos, SLE
• smoking
• aortic atherosclerosis
• congenital cardiac abnormalities (e.g. coarctation of aorta)
• aortitis
• iatrogenic (e.g. during angioplasty/angiography)
• vasculitis
• pregnancy
• crack cocaine

Question 18

What are some features of Marfan syndrome (risk factor for aortic dissection)? (4)

Answer 18

• tall and high arched palate
• pectus excavatum
• joint hypermobility
• autosomal dominant condition

Question 19

What are the first-line investigations for aortic dissection? (4)

Answer 19

• CT angiogram (chest, abdomen and pelvis) - 1st line for definitive diagnosis
• transoesophageal echocardiography
• CXR
• ECG

Question 20

What is the 1st-line imaging for definitive diagnosis of aortic dissection?

Answer 20

CT angiogram of chest, abdomen and pelvis - can see false lumen

Question 21

What imaging can be done for patients with aortic dissection that are too haemodynamically unstable to be taken to CT?

Answer 21

Transoesophageal echocardiography

Question 22

What would a CXR show in aortic dissection?

Answer 22

• widened mediastinum (>8-8.8cm at the level of the aortic knob on portable anteroposterior chest films)
• double aortic contour
• irregular aortic contour
• inward displacement of atherosclerotic calcification (>1cm from aortic margin)

Question 23

What must you always perform in patients with suspected aortic dissection and why?

Answer 23

• ECG to rule out STEMI
• inferior STEMI if RCA occluded with LVH
• survivor bias for those with LCA affected as it is fatal

Question 24

What are some differential diagnoses for aortic dissection? (6)

Answer 24

• ACS
• pericarditis (pleuritic chest pain, diffuse STE)
• aortic aneurysm
• MSK pain
• pulmonary embolism
• mediastinal tumour

Question 25

What is a complicated aortic dissection?

Answer 25

Evidence of end-organ ischaemia

Question 26

What is the 1st line management for type A aortic dissection?

Answer 26

- BP control with beta-blocker or non-dihydropyridine CCB (IV labetalol) - endovascular repair (TEVAR) or open surgery - ASS (aortic root replacement and surgery) - opioid analgesia - vasodilator - (same management for complicated type B aortic dissection)

Question 27

What is the treatment of choice for most patients with type A aortic dissection?

Answer 27

Thoracic endovascular aortic repair (TEVAR)

Question 28

What is the 1st line management for type B aortic dissection?

Answer 28

- BP control with beta-blocker or non-dihydropyridine CCB (IV labetalol) - opioid analgesia - vasodilator - if hypotensive: IV fluids + vasopressors - malperfusion: consider endovascular repair (TEVAR) (or open surgery if complicated)

Question 29

What are some complications of aortic dissection? (4)

Answer 29

- rupture - aortic regurgitation - cardiac tamponade - occlusion of side branches

Question 30

Describe the prognosis of aortic dissection.

Answer 30

Left untreated, can be fatal in 50-60% of patients within 24h Type A - 50% mortality at 48h