Nontraumatic thoracic aortic dissection

Background

  • Most commonly seen in men 60-80 yrs old
  • Intimal tear w/ blood leaking into media

Risk Factors

  • Preexisting aneurysm
  • HTN
  • Inflammatory vasculitis
  • Smoking
  • Cocaine
  • 3rd trimester pregnancy
  • Decelerating trauma
  • Connective tissue disorders (Marfan, Ehlers Danlos syndrome)
  • Bicuspid aortic valve
  • History of surgery (coarctation of aorta repair, aortic valve replacement, cardiac cath)

Classification (Stanford)

  • Type A - Involves any portion of ascending aorta
    • Requires surgery
  • Type B - Isolated to descending aorta
    • Primarily medical management with surgery consultation

Clinical Features

General

  • Symptoms
    • Tearing/ripping pain (10.8x increased disease probability)
    • Migrating pain (7.6x)
    • Sudden chest pain (2.6x)
    • Hx of HTN (1.5x)
  • Signs
    • Focal neurologic deficit (33x)
    • Diastolic heart murmur (acute aortic regurg) (4.9x)
    • Pulse deficit (2.7x)
  • Studies
    • Enlarged aorta or widened mediastinum (3.4x)
    • LVH on admission ECG (3.2x)

Specific

  • Ascending Ao
    • Acute aortic valve regurgitation, leading to a diastolic decrescendo murmur, hypotension, or heart failure, in 50%-66%
    • MI/Ischemia on ECG, usually inferior
    • Cardiac Tamponade
    • Hemothorax - if adventitia disruption
    • Horners, partial - sympathetic ganglion
    • Voice hoarseness - recurrent laryngeal n. compression
    • CVA/Syncope - if carotid extension
    • Neurological deficits
    • SBP>20mmhg difference between arms


  • Descending Ao
    • Chest pain, back pain, abdominal pain
      • Chest Pain - Abrupt, severe (90% of pts) radiating to back
    • Hypertension
    • Hemiplegia, neuropathy (15%)
    • Renal failure
    • Distal Pulse deficits/ Limb ischemia
    • Mesenteric ischemia

Diagnosis

  • ECG
    • Ischemia (esp inferior) - 15%
    • Nonspec ST-T changes - 40%
  • CXR
    • Abnormal in 90%
      • Mediastinal widening (seen in 63%)
      • Left sided pleural effusion (seen in 19%)
      • Widening of aortic contour, displaced calcification (6mm), aortic kinking, double density sign
  • CT Aortogram
    • Study of choice

Differential Diagnosis

Chest pain

Critical

Emergent

Nonemergent

Treatment

Lower wall tension by lowering BP (La Place T = P × r)

  • Control HR before BP: Goal to keep HR 60-80 and SBP 100-120
  1. Beta-Blockers
    1. Esmolol
      1. Advantage of short half life, easily titratable
      2. Bolus 0.1-0.5mg/kg over 1min; infuse 0.025-0.2mg/kg/min
      3. Esmolol Drip Sheet
    2. Labetalol - has both alpha and beta effects
      1. Push dose - 10-20mg w/ repeat doses of 20-40mg q10min up to 300mg
      2. Drip - Load 15-20mg IV, followed by 5mg/hr
    3. Metoprolol
      1. 5mg IV x 3; infuse at 2-5mg/hr
  2. Diltiazem - Use if any contraindications to beta-blockers
    1. Loading 0.25 mg/kg over 2–5 min, followed by a drip of 5mg/h
  3. Vasodilators
    1. Only use if beta-blocker is ineffective
    2. Do not use without a beta-blocker (must suppress reflex tachycardia)
    3. Nicardipine/Clevidipine
    4. Nitroprusside 0.3-0.5mcg/kg/min - Risk of cerebral blood vessel vasodilation and CN/Thiocynate toxicity
    5. Fenoldopam
    6. Enalaprilat
  • Analgesia
  1. Morphine/Fentanyl - Decreases sympathetic output

Complications

  • AV Regurgitation/Insufficiency
    • CHF w/ diastolic murmur
  • Rupture
    • Pericardium: tamponade
    • Mediastinum: hemothorax
  • Vascular obstruction
    • Coronary: ACS
    • Carotid: CVA
    • Lumbar: Paraplegia

See Also

Further References

Source

  • Tintinalli
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