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Aortic dissection

Medicine > Cardiovascular

Background knowledge 🧠

Definition

  • Aortic dissection is a tear in the intima of the aorta, leading to blood entering the aortic wall.
  • The tear creates a false lumen, which may extend along the aorta.
  • Life-threatening condition requiring urgent diagnosis and management.

Epidemiology

  • Incidence: 3-4 per 100,000 annually.
  • More common in men (2:1 ratio).
  • Peak age: 60-70 years.
  • Associated with hypertension in 70% of cases.

Aetiology and Pathophysiology

  • Hypertension: primary risk factor.
  • Connective tissue disorders (e.g., Marfan syndrome, Ehlers-Danlos syndrome).
  • Atherosclerosis.
  • Trauma or iatrogenic causes (e.g., surgery, catheterisation).
  • Cystic medial necrosis: degeneration of the aortic wall.

Types

  • Stanford classification:
    • Type A: involves the ascending aorta (more common and more severe).
    • Type B: confined to the descending aorta.
  • DeBakey classification: types I, II (ascending), and III (descending).

Clinical Features 🌡️

Symptoms

  • Severe, sudden chest pain radiating to the back (“tearing” or “ripping” in nature).
  • Syncope.
  • Shortness of breath.
  • Neurological symptoms (e.g., stroke, paraplegia).
  • Abdominal pain (in Type B dissections).

Signs

  • Blood pressure differential between arms (more than 20 mmHg).
  • Weak or absent peripheral pulses.
  • Diastolic murmur (aortic regurgitation).
  • Signs of shock (hypotension, tachycardia).
  • Neurological deficits.

Investigations 🧪

Tests

  • ECG: may show non-specific changes (rule out myocardial infarction).
  • CXR: widened mediastinum.
  • CT angiography: gold standard for diagnosis.
  • Transoesophageal echocardiography (TOE): for unstable patients.
  • MRI angiography: provides detailed information but less accessible.

Management 🥼

Management

  • Immediate resuscitation: oxygen, IV fluids, analgesia.
  • Blood pressure control: IV beta-blockers (e.g., labetalol).
  • Type A dissection: emergency surgical repair.
  • Type B dissection: medical management initially, endovascular stenting if complications.

Complications

  • Cardiac tamponade.
  • Aortic rupture.
  • End-organ ischaemia (e.g., renal failure, stroke).
  • Aortic regurgitation.
  • Paraplegia (due to spinal cord ischaemia).

Prognosis

  • Mortality: up to 20% within 24 hours for untreated Type A dissections.
  • Surgical outcomes better for Type A with early intervention.
  • Type B has lower mortality but significant risk if complications arise.

Key Points

  • Aortic dissection is a life-threatening condition requiring urgent diagnosis.
  • Type A dissections require emergency surgery.
  • CT angiography is the investigation of choice.
  • Early intervention improves survival.

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Cardiovascular