Aortic dissection

Question 1

What is aortic dissection?

Answer 1

Condition where a tear in the aortic tunica 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 is an aortic dissection classified?

Answer 2

1. Stanford Classification
   - Stanford Type A (2/3 of cases) → any dissection involving the ascending aorta
   - Stanford Type B (1/3 of cases) → any dissection involving the descending aorta only (distal to left subclavian artery)
2. DeBakey Classification
   - Type I → dissection involves ascending and descending aorta
   - Type II → dissection involves only ascending aorta (up to the brachiocephalic artery)
   -Type III → involves only descending aorta (distal to left subclavian artery)

Question 3

What are the causes/ risk factors of aortic dissection?

Answer 3

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

Risk factors:
- Hypertension (most important RF)
- Trauma
- Marfan Syndrome (tall + high-arched palate, Autosomal Dominant)
- Ehlers-Danlos Syndrome
- Bicuspid Aortic Valve
- Smoking

Question 4

Summarise the epidemiology of aortic dissection

Answer 4

● Most common in males aged 40-60 yrs

Question 5

What are the presenting symptoms of an aortic dissection?

Answer 5

1. Sudden & Severe tearing chest pain
2. Interscapular (radiates to back) pain
3. Asymmetrical BP & Pulse between limbs (mainly arms)
   - May also have weak or absent carotid, brachial, or femoral pulse.
   - Radio-radial delay and radio-femoral delay
4. Early Diastolic Murmur (Aortic Regurgitation)
   - Austin Flint Murmur ⇒ mid-diastolic murmur best heard at the apex. Sign of severe aortic regurgitation.
5. Focal Neurological Deficits (eg. Horner’s Syndrome in carotid dissection)
6. Hypertension
7. Features of Marfan Syndrome or Ehlers-Danlos Syndrome

Question 6

What signs of an aortic dissection can be found on physical examination?

Answer 6

1. Murmur on the back (below the left scapula), descending to the abdomen 
2. Hypertension 
3. Blood pressure difference between the two arms> 20 mm Hg 
4. Wide pulse pressure 
5. Perfusion deficit:
   - Pulse deficit (reduced or absent pulse)
   - Focal neurological deficit including: paraesthesia, weakness, paraplegia.
6. Hypotension may suggest tamponade (build up of fluid in pericardial sac) 
7. Pulsus paradoxus= abnormally large decrease in systolic blood pressure and pulse wave amplitude during inspiration

Question 7

What investigations are used to diagnose/ monitor aortic dissection?

Answer 7

1. CT Angiogram (Chest, Abdomen, Pelvis) → first-line imaging for definitive diagnosis. Can see false lumen.
   - Transoesophageal Echocardiography → can be done for unstable patients who are unable to be taken to CT scanner.
2. Contrast-enhanced computed tomography- gold-standard investigation for the diagnosis of aortic dissection
3. CXR → widened mediastinum
4. ECG → always perform in patients with acute chest pain to rule out STEMI
5. Transthoracic Echocardiography → can see intimal flap & two lumens
6. Troponin → exclude MI

Question 8

How is aortic dissection managed?

Answer 8

1. Type A → surgical management. May be open surgery or endovascular repair.
2. Type B → conservative management, bed rest, IV Beta Blockers (Labetalol) to reduce BP.
3. Hypotensive Patients → IV Fluids, Vasopressors

Question 9

What complications may arise from aortic dissection?

Answer 9

• Death due to internal haemorrhage
• Rupture
• End organ damage (renal or cardiac failure)
• Cardiac tamponade- (hypotension, raised JVP, muffled heart sounds)
• Stroke
• Limb ischaemia
• Mesenteric ischaemia
• coronary dissection - ECG shows ST elevation in the inferior leads