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

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

• Hypertensive Emergency
• Aortic Transection
• Abdominal Aortic Aneurysm (AAA)

Further References

• NNT Aortic Dissection LRs
• AHA Full Guidelines
• AHA Quick Summary
• ALiEM Paucis Verbis: International Registry on Aortic Dissection (IRAD)

Source

• Tintinalli