#5 – Aortic Dissections

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Cliff Reid - SMACC 2015

Cliff Reid – SMACC 2015


  • 1st described by German anatomist Daniel Sennert in 16th century on autopsy
  • King George II of England died of aortic dissection in 1760 and described by Frank Nichols
  • John Ritter (Actor) died of dissection
  • Relatively uncommon, but can be fatal if missed
  • 3-5 cases/100,000 each year
  • Mortality rates around 25%
  • 22% undiagnosed prior to death


  • Tear in aortic intima that leads to false lumen between intima and media
    • majority occur in ascending aorta between the sinotubular junction and left subclavian artery
  • Bimodal age distribution
    • Teens-30yo and > 50yo

Risk Factors

  • Chronic hypertension
  • Connective tissue disorders
    • Marfans, Ehler-Danlos
  • Bicuspid aortic valve
  • Previous aortic instrumentation
  • Family history of dissections


  • DeBakey (older)
    • Uses site of origin
      • Type I
        • Originates in ascending and includes the arch
      • Type II
        • Originates and confined to ascending aorta
      • Type III
        • Originates in descending and extends proximal/distal
  • Stanford (more widely used)
    • Stanford A
      • Involves the ascending aorta
    • Stanford B
      • Everything else
  • Newer DISSECT classification can be used to help with treatment options
    • Duration
      • Acute = < 2 weeks
      • Subacute = 2 weeks to 3 months
      • Chronic = > 3 months
    • Intimal Tear
      • Primary location
        • Ascending
        • Aortic Arch
        • Descending
        • Abdomen
    • Size of Aorta
      • Maximum trans-aortic diameter within dissected segment
    • Segmental Extent of aortic involvement
      • Broken down in to sections from arch to iliacs
    • Clinical complications associated with dissection
    • Thrombus of aortic false lumen
      • Patent or not

Clinical Presentations

  • History
    • Pain (90%)  – sharp > ripping/tearing
      • Chest in Type A (83%)
      • Back (64%) and abdominal (43%) in Type B
    • Neurologic
      • Syncope, stroke symptoms (more common in Type A)
      • Type B – paraplegia from Artery of Adamkiewicz
      • Horner’s Syndrome from compression on superior cervical ganglion
      • Hoarseness from compression on left recurrent laryngeal nerve
  • Physical Exam
    • Tamponade (most common cause of death) in Type A or Type I
      • Beck’s Triad
        • Hypotension, JVD, muffled heart tones
    • Can be hypertensive or hypotensive
    • Pulse deficits (> 20mmHg variation)
      • Higher mortality if present
      • Depends on the site (up to 30% of Type A vs 10% of Type B)
      • Older patients less likely to have pulse discrepancy
    • Heart murmur (more common in younger patients)
      • Aortic regurgitation (50-66%)
        • Diastolic decrescendo murmur
        • Heard best over right sternal border
          • as opposed to classic primary aortic disease AR which is heard over the left sternal border
  • Pre-test Probability
    • 77% of patients have 2 out of the 3 high-risk variables:
      • Variation in pulse or blood pressure
      • Presence of CXR abnormality
      • Abrupt onset of sharp, chest/abdominal pain

Diagnostic Studies

  • EKG (almost always 1st study done for chest pain)
    • Not very helpful other than to R/O ACS
      • May be normal in 19-31% of dissections
    • May see abnormal changes if dissection involves coronary arteries
  • Chest Radiograph
    • Classic finding is widening of the mediastinum or aortic silhouette
      • Incidence ~ 60%
    • Up to 30% of patients with aortic dissection have no CXR abnormality

  • D-Dimer
    • Extensively studied…but essentially worthless
      • When < 500 ng/mL:
        • Sensitivity – 97%, Negative Predicative Value – 96%
        • Specificity – 56%
        • False negative rate of 18%
  • Computed Tomography Angiography (hemodynamically stable)
    • Test of choice for diagnosis
    • Findings of acute dissection:
      • Intimal flap
      • True and false lumen
      • Pericardial effusion
  • Echocardiography (hemodynamically unstable)
    • Transesophageal (preferred)
      • Sensitivity/specificity can approach CT numbers
      • Require procedural sedation
    • Transthoracic (acceptable)
      • Quicker, no sedation, inferior sensitivity/specificity to CT

Intimal Flap


  • Acute Management
    • Control of heart rate and blood pressure
      • Systolic BP < 120 mmHg
      • Heart rate < 60 bpm
    • Medications
      • IV Beta-blocker (1st line)
        • Esmolol (0.1-0.5 mg/kg over 1 minute followed by 0.025-0.2 mg/kg/hr)
        • Labetalol (20mg bolus followed by 0.5-2 mg/hr)
        • Propanolol (1-10mg load followed by 3 mg/hr)
      • If hypertensive after beta-blockade:
        • Nitroprusside (0.25-0.5 mcg/kg/min)
        • Nicardipine (5mg/hr, increase 2.5 mg/hr q15min to max 15mg/hr)
  • Definitive Management
    • Type A (surgical emergency)
      • Mortality rate 1-2% per hour after symptom onset
      • Open repair on bypass
        • Median sternotomy with graft placement +/- aortic valve replacement
        • May need to re-implant coronary and/or great vessels
      • > 90% 3yr survival after surgery


  • Type B
    • Uncomplicated
      • Medical therapy
        • BP goal = < 120/80 mmHg
        • Oral beta-blocker is 1st line
        • Add ACE inhibitors or calcium channel blocker to BP goal
      • Serial Imaging
        • CT or MRI at 3, 6, and 12 months
        • If no progression, then every 1-2 years
      • Complicated (or progressing)
        • Endovascular graft surgery
          • Indications
            • Involvement of major aortic branch leading to end organ ischemia
            • Persistent HTN or pain
            • Aneurysmal dilation
            • Concomitant connective tissue disorder



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