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Cliff Reid – SMACC 2015

Background

• 1^st described by German anatomist Daniel Sennert in 16^th 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

Pathophysiology

http://tinyurl.com/hbq64t8

• 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

Classification

• 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

http://tinyurl.com/j3eo99n

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 1^st 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
    

    http://tinyurl.com/zd6qoq4

• 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

http://tinyurl.com/jygxmrx

http://tinyurl.com/zypu38w

• Echocardiography (hemodynamically unstable)
  • Transesophageal (preferred)
    • Sensitivity/specificity can approach CT numbers
    • Require procedural sedation
  • Transthoracic (acceptable)
    • Quicker, no sedation, inferior sensitivity/specificity to CT

http://tinyurl.com/jcb7gf5

Treatment

• 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

http://tinyurl.com/j5jbaz3

• Type B
  • Uncomplicated
    • Medical therapy
      • BP goal = < 120/80 mmHg
      • Oral beta-blocker is 1^st line
      • Add ACE inhibitors or calcium channel blocker to BP goal
    • Serial Imaging
      

      http://tinyurl.com/z7zm9zp

      • 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

References

1. Sennertus D: Cap. 42, Op Omn Lib. 5:306-315, 1650
2. Nichols F. Observations concerning the body of his late majesty, October 26, 1760, Phil Trans Lond. 52:265-274, 1761.
3. Pacini D, Di marco L, Fortuna D, et al. Acute aortic dissection: epidemiology and outcomes. Int J Cardiol. 2013;167(6):2806-12.
4. Hagan PG, Nienaber CA, Isselbacher EM, et al. The International Registry of Acute Aortic Dissection (IRAD): new insights into an old disease. JAMA. 2000;283(7):897-903.
5. Olsson  C, Thelin  S, Stahle  E  et al.: Thoracic aortic aneurysm and dissection: increasing prevalence and improved outcomes reported in a nationwide population-based study of more than 14,000 cases from 1987-2002. Circulation 114: 2611, 2006.
6. E. DeBakey, W.S. Henley, D.A. Cooley, G.C. Morris, E.S. Crawford, A.C. Beall. Surgical management of dissecting aneurysms of the aorta.  J Thorac Cardiovasc Surg. 1965;49:130–149
7. O. Daily, H.W. Trueblood, E.B. Stinson, R.D. Wuerflein, N.E. Shumway. Management of acute aortic dissections.  Ann Thorac Surg. 1970;10:237–247.
8. Dake MD, Thompson M, Van sambeek M, Vermassen F, Morales JP. DISSECT: a new mnemonic-based approach to the categorization of aortic dissection. Eur J Vasc Endovasc Surg. 2013;46(2):175-90.
9. Dake MD, Thompson M, Van sambeek M, Vermassen F, Morales JP. DISSECT: a new mnemonic-based approach to the categorization of aortic dissection. Eur J Vasc Endovasc Surg. 2013;46(2):175-90.
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16. Shimony A, Filion KB, Mottillo S, Dourian T, Eisenberg MJ. Meta-analysis of usefulness of d-dimer to diagnose acute aortic dissection. Am J Cardiol. 2011;107(8):1227-34.
17. Sueyoshi E, Nagayama H, Hayashida T, Sakamoto I, Uetani M. Comparison of outcome in aortic dissection with single false lumen versus multiple false lumens: CT assessment. Radiology. 2013;267(2):368-75.
18. Moore AG, Eagle KA, Bruckman D, et al. Choice of computed tomography, transesophageal echocardiography, magnetic resonance imaging, and aortography in acute aortic dissection: International Registry of Acute Aortic Dissection (IRAD). Am J Cardiol. 2002;89(10):1235-8.
19. Hiratzka LF, Bakris GL, Beckman JA, et al. 2010 ACCF/AHA/AATS/ACR/ASA/SCA/SCAI/SIR/STS/SVM guidelines for the diagnosis and management of patients with Thoracic Aortic Disease: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines, American Association for Thoracic Surgery, American College of Radiology, American Stroke Association, Society of Cardiovascular Anesthesiologists, Society for Cardiovascular Angiography and Interventions, Society of Interventional Radiology, Society of Thoracic Surgeons, and Society for Vascular Medicine. Circulation. 2010;121(13):e266-369.
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