Cardiovascular System >
Aortic Dissection

“Tear in inner layer of aorta → leading to haematoma between intima and media layer of aorta”

Risk Factors
  • Male between 40-80 years old – peak at 60-80 years
  • Marfan syndrome
Aetiology
  • Hypertension (increases risk of rupture)
  • Trauma
    • Deceleration injury- motorcycle accident
    • Iatrogenic injury during valve replacement/ graft surgery
  • Vasculitis w aortic involvement ( syphilis)
  • Recreational drug-Amphetamines/cocaine
  • Atherosclerosis
  • 3rd-trimester pregnancy
  • Congenital
    • CT disease- Marfan, Ehlers- Danlos syndrome
    • Bicuspid aortic valve
    • Coarctation of aorta 
Pathophysiology
  1. Transverse tear in intima → blood entering  space in between intima and media forming a false lumen
  2. Causes the formation of haematoma, which can move and increase in size
  3. A rise in pressure can cause the aortic wall to rupture leading to occlusion of branching vessels → ischaemia in area
  4. Second intima tear can result in re-entry into the normal aortic lumen

Classifications of Aortic Dissection

  • Stanford ( more common) → by aorta involvement e.g.  ascending/ descending aorta
    • Type A–  Ascending Aorta  ( proximal to brachiocephalic artery- extends proximally to aortic arch & distally to descending aorta)
    • Type B – any dissection not involving ascending,
    • Tx: medically * BB, vasodilators
  • DeBakey → by origin and extent
    • Type I: originates in ascending aorta to aortic arch & descending aorta
    • Type II: dissection originated and restricted to ascending aorta
    • Type III descending aorta, extends distally
      • Type IIIa – descending thoracic aorta above level of the diaphragm
      • Type IIIb extends below diaphragm
Clinical Presentation
  • Sudden severe tearing/ ripping pain
    • In anterior chest or back
    • Interscapular or retrosternal pain
    • Neck & jaw or abdomen (colicky pain )
    • Migrated as dissected wall propagates caudally
  • Further signs
    • HTN/ Hypotension
    • Asymmetrical BP and pulse readings bw limbs
    • Syncope diaphoresis, confusion or agitation
    • Heart murmur- aortic regurgitation in proximal dissection
Investigations
  • Detect aortic dissection risk score (ADD- RS )
  • ECG
  • Lab studies: D- Dimer ( elevated), evaluate for signs of end-organ damage, troponin, BMP, lactate
  • Pre-op labs- CBC, type & screen, BMP, coagulation panel
  • Imaging:
    • CXR, AP view
    • CT angiography of chest, abdomen et pelvis
    • MRA of chest, abdomen and pelvis
    • Transoesophageal echocardiography
    • Catheter angiography, ultrasound
Management
  • Surgery – !only in pat w suspected of confirmed dissection!
    • Open surgery w/ graft
    • Endovascular treatment w aortic stent implantation ( type B dissection and if the operative risk to high)
    • Stanford A – immediate surgery
    • Stanford B – treat conservatively unless a complication
      • (end-organ damage, Hypotension, persistent  severe chest pain or HTN) propagation of dissection, expanding aneurysm/ haematoma)
  • Blood Pressure Control:
    • Hypotensive patients:
      • !avoid inotropes- worsen aortic wall stress
      • Haemodynamic support:
        • Target MAP of 70 mmHg or euvolemia
        • IV fluids,
        • Vasopressor support if pat remain hypotensive
        • Norepinephrine, phenylephrine,
        • Identify & treat comorbidities 
    • Hypertensive patients:
      • Control HTN- control & target 100-120 mmHG & HR ≤ 60bpm
      • Start w IV blocker – to avoid reflex tachycardia
      • Esmolol, labetalol
      • Follow w vasodilator ( IV sodium nitroprusside)
      • If BB contraindicated – calcium channel blocker ( verapamil, diltiazem)
  • Supportive Care:
    • The patient may require sedation – analgesia ( Morphine)
    • Identify & treat complications (AKI & mesenteric ischaemia)
    • Avoid thrombolytic tx in patients w suspected aortic dissection
Complications
  • Aortic rupture & acute blood loss – acute back and flank pain
  • MI
  • Aortic regurgitation
  • Cardiac tamponade combined w cardiogenic shock
  • Pericarditis 
  • Stroke
  • Bleeding into thorax, mediastinum & abdomen
  • Arterial occlusion & ischaemia depending on location
Prevention
  • BP control
  • Smoking cessation
  • Screening
  • Repair of rapidly expanding aneurysm

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