Aortic Dissection

Question 1

Define aortic dissection

Answer 1

Separation of the aortic wall tunica intima, resulting in blood flow into a false lumen composed of the inner and outer layers of the tunica media

Question 2

How is aortic dissection classified

Answer 2

Stanford Classification:
- Type A: dissection involving the ascending aorta
- Type B: dissection involving the descending aorta (after left subclavian branch)

De Bakey classification:
- Type I – originates in ascending aorta, propagates to at least the aortic arch and possibly beyond it distally
- Type II – originates in and is confined to the ascending aorta
- Type III – originates in descending aorta, rarely extends proximally but will extend distally

Question 3

Aetiology of aortic dissection

Answer 3

• Chronic Hypertension
• Inherited conditions: Marfan’s, Ehlers-Danlos
• Bicuspid aortic valve
• Aortic atherosclerosis with dilation
• Inflammatory conditions
• Traumatic conditions
• Iatrogenic: aortic manipulation associated with cardiac surgery
• Loeys-Dietz syndrome (hypertelorism, bifid uvula, arterial tortuosity)

As dissection propagates → false lumen may occlude branches of aorta (coronary, brachiocephalic, intercostal, visceral, renal or iliac)
Haematoma may propagate into vessel wall → occlude side branches

Question 4

Symptoms of aortic dissection

Answer 4

Chest pain: sudden onset, tearing, radiates interscapularly
Syncope

Carotid → blackouts, hemiparesis (Cerebral ischaemia)
Coronary → MI, angina
Renal → AKI, renal failure
Coeliac trunk → abdominal pain (visceral ischaemia)

Poor perfusion → limb pain
Heart failure → dypsnoea

Question 5

Signs of aortic dissection

Answer 5

Obs: Hypotension (shock or tamponade) OR HTN

General
- Altered mental status (cerebral ischaemia)
- Pallor (poor perfusion)

Cardio
- BP >20mmHg discrepancy between arms
- Wide pulse pressure
- Collapsing pulse
- Early diastolic murmur (aortic regurgitation)
- Weak pulse

Resp
- Pleural effusion: L-sided reduced breath sounds, dullness on percussion

Neuro
- Focal neurological deficits
- Horner’s syndrome (classically ptosis, miosis and anhidrosis)

Question 6

Investigations for aortic dissection

Answer 6

Stable (most commonly) → CTA CAP
Unstable (cannot be taken to CT) → TOE/TTE

ECG: ?MI, ST depression

FBC
U&Es
Troponin
D-dimer
Cross match & G&S
Smooth muscle myosin heavy chain protein: elevated
Renal screen: ?perfusion
LFTs: ?perfusion
VBG/ABG: ?perfusion

CXR: widened mediastinum and aortic notch
CT chest: false lumen, intimal flap
Transthoracic/oesophagela echo: intimal flap
MRI
Intravascular US

Question 7

Management for aortic dissection

Answer 7

A-E

Unstable: haemodynamic support + O2

1. Blood pressure control - IV beta blocker
2. Analgesia
3. Vasodilators
4. Surgery (open or endosvascular stent-graft repair)

Type A: Usually requires surgical management (e.g. aortic graft)
Type B: Normally managed conservatively with blood pressure control. If there is evidence of end organ damage then endovascular/open repair may be performed.

Question 8

Complications of aortic dissection

Answer 8

Pericardial tamponade
Aortic incompetence
MI
Aneurysmal rupture
Regional ischaemia

Question 9

Prognosis of aortic dissection

Answer 9

If untreated, false channel rupture with fatal exsanguination in 50-60% within 24hr