Nontraumatic thoracic aortic dissection

Not to be confused with traumatic aortic transection

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)

Acute Aortic Dissection (ADD) Risk Score

Predisposing conditions Pain features Physical findings
  • Marfan syndrome
  • Connective tissue disease
  • Family history of aortic disease
  • Recent aortic manipulation
  • Known thoracic aortic aneurysm

Chest, back, or abdominal pain described as:

  • Abrupt in onset/severe in intensity

AND

  • Ripping/tearing/sharp or stabbing quality
  • Evidence of perfusion deficit
    • Pulse deficit
    • Systolic BP differential
    • Focal neuological deficit (in conjunction with pain)
  • Murmur of aortic insufficiency (new or not known to be old and in conjunction with pain)
  • Hypotension of shock state
Score^ Category Prevalence
0 Low 6%
1 Intermediate 27%
>1 High 39%

^Number of risk categories with one positive

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

Differential Diagnosis

Chest pain

Critical

Emergent

Nonemergent

Hypertension

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
    • Similar Sn and Sp to TEE and MRA
  • Other considerations
    • There are no clinical rules yet to r/o low and very low risk groups
    • D-dimer
      • Sn 0.97 and Sp 0.56 (NPV 0.96)[1]
      • ACEP considers rates use of D-dimer as Level C[2]
    • Bedside US
      • Can help in ruling in patients when AOFT is >4cm


Management

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
    • Esmolol
      • Advantage of short half life, easily titratable
      • Bolus 0.1-0.5mg/kg over 1min; infuse 0.025-0.2mg/kg/min
      • Esmolol Drip Sheet
    • Labetalol - has both alpha and beta effects
      • Push dose - 10-20mg w/ repeat doses of 20-40mg q10min up to 300mg
      • Drip - Load 15-20mg IV, followed by 5mg/hr
    • Metoprolol
      • 5mg IV x 3; infuse at 2-5mg/hr
  2. Diltiazem - Use if any contraindications to beta-blockers
    • Loading 0.25 mg/kg over 2–5 min, followed by a drip of 5mg/h
  3. Vasodilators
    • Only use if beta-blocker is ineffective
    • Do not use without a beta-blocker (must suppress reflex tachycardia - shear forces from increased HR)
    • Nicardipine/Clevidipine - consider following regimen for nicardipine:
      • 5 mg/hr start, then titrate up by 2.5 mg/hr every 10 min until goal
      • Once at goal, drop to 3 mg/hr and re-titrate from there
      • May initially bolus 2 mg IV[3]
    • Nitroprusside 0.3-0.5mcg/kg/min - Risk of cerebral blood vessel vasodilation and CN/Thiocynate toxicity
    • Fenoldopam
    • Enalapril
  4. Analgesia

Complications

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

See Also

External Links

References

  1. ↑ Shimony A, et al. Meta-analysis of usefulness of d-dimer to diagnose acute aortic dissection. Am J Cardiol. 2011; 107(8):1227-1234.
  2. ↑ Diercks DB, et al. Clinical policy: Critical issues in the evaluation and management of adult patients with suspected acute nontraumatic thoracic aortic dissection. Ann Emerg Med. 2015; 65(1):32-42e12.
  3. ↑ Curran MP et al. Intravenous Nicardipine. Drugs 2006; 66(13): 1755-1782. http://emcrit.org/wp-content/uploads/2014/07/bolus-dose-nicardipine.pdf
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