Aortic Dissection

Aka: Aortic Dissection

1. Epidemiology
   1. Gender: Most common in males by factor of 2-3 to 1
   2. Age: 40-80 years old
   3. Incidence: 2000 per year in US
2. Pathophysiology
   1. Aortic Dissection has a very different mechanism than Abdominal Aortic Aneurysm
      1. AAA is caused by atherosclerosis and involves all three layers of aorta wall
      2. Aortic Dissection is caused by Hypertension and involves only one layer (intima)
   2. Intimal tear precedes dissection
3. Risk Factors
   1. Male gender
   2. Pregnancy
   3. Cocaine abuse or other Sympathomimetics
   4. Chronic Hypertension (present in 70-90% of cases)
   5. Bicuspid aortic valve
   6. Aortic Coarctation
   7. Giant Cell Arteritis
   8. Cardiovascular procedures
      1. Cardiac surgery
      2. Cardiac catheterization
   9. Connective Tissue Disease
      1. Marfan's Syndrome
      2. Ehlers-Danlos Syndrome
4. Types: Standford Classification
   1. Type A (60-65%)
      1. Ascending Aorta
   2. Type B (30-35%)
      1. Descending Aorta (after origin of subclavian artery)
5. Symptoms
   1. Chest Pain (Universal)
      1. Severe tearing sensation
      2. Aortic Dissection pain radiates to back or Abdomen
         1. Myocardial Infarction rarely radiates like this
      3. Aortic Dissection pain is most severe at onset
         1. Myocardial Infarction pain is crescendo in nature
   2. Neurovascular symptoms
      1. Cerebrovascular Accident
      2. Syncope
6. Symptoms: Test Sensitivity at presentation with Aortic Dissection (based on IRAD Data)
   1. Timing
      1. Sudden onset: 85%
   2. Severity
      1. Severe pain: 90%
   3. Characteristics
      1. Sharp pain: 64%
      2. Tearing/ripping: 50%
         1. Type A: 49%
         2. Type B: 52%
   4. Distribution
      1. Anterior Chest Pain: 61%
         1. Type A: 71%
         2. Type B: 44%
      2. Back pain: 53%
         1. Type A: 46%
         2. Type B: 64%
      3. Abdominal Pain: 35%
         1. Type A: 22%
         2. Type B: 42%
      4. Migrating pain: 17%
         1. Type A: 15%
         2. Type B: 19%
   5. Associated Findings
      1. Pain: 95%
         1. Type A: 94%
         2. Type B: 98%
      2. Syncope: 9%
         1. Type A: 13%
         2. Type B: 4%
7. Signs
   1. Blood Pressure at presentation (based on IRADS results)
      1. Hypertensive SBP>150: 49%
         1. Type A: 36%
         2. Type B: 70%
      2. Normotensive SBP 100-150: 35%
      3. Hypotensive or shock SBP: 16%
         1. Type A: 25%
         2. Type B: 4%
   2. Pulse deficit: 15%
      1. Type A: 19%
      2. Type B: 9%
   3. Aortic murmur: 30%
   4. Cardiac Tamponade findings
   5. Findings associated with dissection of hematoma
      1. Cerebrovascular Accident
      2. Hemiplegia
      3. Pulse deficits
      4. Aortic Insufficiency
8. Diagnosis
   1. Electrocardiogram
      1. Left Ventricular Hypertrophy
      2. Myocardial Ischemia
      3. Myocardial Infarction
   2. Chest XRay
      1. Mediastinal widening (progressive)
9. Imaging
   1. Aortic Angiography (gold standard)
      1. Accuracy
         1. Sensitivity: 90-98%
         2. Specificity: 95-98%
   2. CT Chest
      1. Sensitivity: 94%
      2. Specificity: 90%
   3. Transesophageal Echocardiogram (Increasingly popular)
      1. Sensitivity: 97%
      2. Specificity: 75-90%
   4. MRI Chest
      1. Sensitivity: 98%
      2. Specificity: 98%
10. Complications
    1. Neurologic deficits
       1. Cerebrovascular Accident
    2. Unequal perfusion
       1. Unequal pulses
       2. Unequal extremity Blood Pressures
    3. Myocardial Ischemia
    4. Myocardial Infarction
    5. Aortic Regurgitation
    6. Cardiac Tamponade
11. Management
    1. Lower Blood Pressure
       1. Nicardipine
       2. Esmolol
       3. Nitroprusside 0.5-10 ug/kg/min IV
       4. Labetalol 20-40 mg incremental boluses IV
       5. Trimethaphan 1-4 mg/min IV
    2. Proximal Aortic Dissection
       1. Surgical Management
    3. Distal Aortic Dissection
       1. Medical Management
12. References
    1. Dachs (2012) Board Review Express, San Jose
    2. Bushnell (2005) Ann Emerg Med 46:90-92
    3. Gupta (2009) Pharmaceuticals 2: 66-76
    4. Hagan (2000) JAMA 283: 897-203