Cardiovascular Medicine Book

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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. Precautions
    1. Keep Aortic Dissection in the Chest Pain differential diagnosis
    2. Aortic Dissection may present in similar fashion to Acute Coronary Syndrome, Pulmonary Embolism, Pericarditis
    3. Atypical presentations are very common with a wide variety of findings that mimic other conditions
      1. Transient global amnesia or Altered Mental Status
      2. Painless lower extremity weakness
      3. New onset CHF with ST Elevation MI
      4. Renal or Intestinal Ischemia
  4. 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. Family History of aortic disease
    9. Thoracic aortic aneurysm or prior dissection history
    10. Cardiovascular procedures (especially recent)
      1. Cardiac or aorta surgery
      2. Cardiac catheterization
    11. Connective Tissue Disease
      1. Marfan's Syndrome
      2. Ehlers-Danlos Syndrome
  5. Types: Standford Classification
    1. Type A (60-65%, Debakey Type I and II)
      1. Ascending Aorta and/or aortic arch (dissection may extend intracardiac)
    2. Type B (30-35%, Debakey Type III)
      1. Descending Aorta (after origin of subclavian artery)
  6. Symptoms
    1. Chest Pain (Universal)
      1. Severe, sudden tearing sensation in the chest, back or Abdomen
      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 typically crescendo in nature
    2. Neurovascular symptoms
      1. Cerebrovascular Accident
      2. Syncope
      3. Extremity Paresthesias
  7. Symptoms: Test Sensitivity at presentation with Aortic Dissection (based on IRAD Data)
    1. Classic Triad (100% Test Specificity if present, but most cases are atypical and do not have all 3 findings)
      1. Severe abrupt onset, ripping or tearing Chest Pain that radiates to back AND
      2. Pulse deficit or difference in upper extremity Blood Pressure >20 mmHg AND
      3. Mediastinal widening or aortic knob widening on Chest XRay
    2. Timing
      1. Sudden onset: 85%
    3. Severity
      1. Severe pain: 90%
    4. Characteristics
      1. Pain: 95%
        1. Type A: 94%
        2. Type B: 98%
      2. Sharp pain: 64%
      3. Tearing/ripping: 50%
        1. Type A: 49%
        2. Type B: 52%
    5. 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%
    6. Associated Findings
      1. Syncope: 9%
        1. Type A: 13%
        2. Type B: 4%
  8. 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%
      4. Blood Pressure differential between sides
        1. Poor sensitivity and Specificity for Aortic Dissection
        2. Up to 20% of normal patients have a Blood Pressure differential of at least 20 mmHg
    2. Pulse on presentation
      1. Pulse deficit: 15%
        1. Type A: 19%
        2. Type B: 9%
        3. Positive Likelihood Ratio when associated with acute Chest Pain or back pain: 5.3
          1. Von Kodolitsch (2000) Arch Intern Med 160(19): 2977-82 [PubMed]
      2. Palpable pulse differential
        1. Less prominent pulse (e.g. radial pulse) on one side compared with the other
    3. Aortic Murmur: 30%
      1. Aortic Regurgitation murmur suggests a Type A dissection with intracardiac involvement
    4. Cardiac Tamponade findings
    5. Findings associated with dissection of hematoma
      1. Cerebrovascular Accident
      2. Focal neurologic deficit (e.g. Hemiplegia)
      3. Pulse deficits
      4. Aortic Insufficiency
  9. Labs
    1. D-Dimer
      1. Consider when evaluating differential diagnosis
      2. Normal D-Dimer (10% false negative) does not exclude thoracic dissection
  10. Diagnostics
    1. Electrocardiogram
      1. Test Sensitivity: 69%
      2. Test Specificity: Low (non-diagnostic)
      3. Left Ventricular Hypertrophy
      4. Myocardial Ischemia
      5. Myocardial Infarction
  11. Imaging
    1. Aortic Angiography (gold standard)
      1. Test Sensitivity: 90-98%
      2. Test Specificity: 95-98%
    2. CT Angiography Chest (Chest CTA) - preferred first line study
      1. Similar efficacy to Transesophageal Echocardiogram (TEE) or MRA
      2. Test Sensitivity: 100% with new generation CT (older studies quoted 94%)
      3. Test Specificity: 98% with new generation CT (older studies quoted 90%)
    3. Transesophageal Echocardiogram
      1. Test Sensitivity: 97%
      2. Test Specificity: 75-90%
    4. MRA Chest
      1. Not recommended as an emergency evaluation (may be indicated in some stable patients)
      2. Test Sensitivity: 98%
      3. Test Specificity: 98%
    5. Chest XRay
      1. Test Sensitivity: 90%
      2. Test Specificity: Low (non-diagnostic)
      3. Unlikely to demonstrate anything more than intrathoracic catastrophe
      4. Mediastinal widening (progressive), aortic knob widening
      5. Tracheal, Bronchial or esophageal deviation
      6. Pleural Effusion
  12. 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 (with Cardiogenic Shock)
    6. Aortic valve rupture
    7. Cardiac Tamponade
  13. Management
    1. Lower Blood Pressure (in addition to Heart Rate lowering)
      1. Blood Pressure goal: <120 mmHg (based on consensus expert opinion)
      2. Heart Rate goal: <60 bpm (based on consensus expert opinion)
      3. Nicardipine
      4. Esmolol
      5. Nitroprusside 0.5-10 ug/kg/min IV
      6. Labetalol 20-40 mg incremental boluses IV
      7. Trimethaphan 1-4 mg/min IV
    2. Proximal Aortic Dissection
      1. Surgical Management
    3. Distal Aortic Dissection
      1. Medical Management
  14. Prognosis
    1. High mortality: 27% even under ideal conditions
    2. Mortality increases 1-3% per hour from onset (first 48 hours)
  15. References
    1. Dachs (2012) Board Review Express, San Jose
    2. Jhun, Grock and Weinstock in Herbert (2016) EM:Rap 16(11): 11-12
    3. Orman and Mattu in Herbert (2015) EM:Rap 15(8):2-3
    4. (2015) Ann Emerg Med 651(1): 32-42 [PubMed]
      1. http://www.acep.org/workarea/DownloadAsset.aspx?id=100814
    5. Bushnell (2005) Ann Emerg Med 46:90-92 [PubMed]
    6. Gupta (2009) Pharmaceuticals 2: 66-76 [PubMed]
    7. Hagan (2000) JAMA 283: 897-203 [PubMed]

Dissection of aorta (C0340643)

Definition (NCI) A progressive tear in the aorta characterized by a separation of the media layer from the outer-most layer.
Concepts Disease or Syndrome (T047)
ICD9 441.00
ICD10 I71.0, I71.00
SnomedCT 308546005
English Dissection of aorta [any part], Aortic Dissection, dissection of aorta, dissection of aorta (diagnosis), Dissection of aorta, Dissecting aortic aneurysm, unspecified site, Aortic dissection, Dsct of aorta unsp site, aortic dissection, Dissection of unspecified site of aorta, Dissection of aorta, unspecified site, dissection aorta, dissection aortic, aorta dissection, aorta dissections, aortic dissections, Dissecting aneurysm of aorta, unspecified site, Dissecting aneurysm of aorta, AORTIC DISSECTION, DISSECTION, AORTIC, Dissection of aorta (disorder), dissection; aorta, aorta; dissection
Italian Dissezione dell'aorta, Aneurisma dissecante dell'aorta, sede non specificata
Dutch aneurysma dissecans op niet-gespecificeerde plaats, aorta; dissectie, dissectie; aorta, Dissectie van aorta [elk deel], aorta dissecans
French Anévrysme aortique disséquant, site non précisé, Dissection aortique
German dissezierendes Aortenaneurysma, unspezifische Stelle, Dissektion der Aorta [jeder Abschnitt], Aortendissektion
Portuguese Aneurisma dissecante da aorta, local NE, Dissecção da aorta
Spanish Aneurisma disecante de aorta, localización no especificada, disección aórtica (trastorno), disección de aorta, disección aórtica, disección de aorta (trastorno), Disección aórtica
Japanese 大動脈解離, 解離性大動脈瘤、部位不明, カイリセイダイドウミャクリュウブイフメイ, ダイドウミャクカイリ
Czech Disekující aneurysma blíže neurčené části aorty, Aortální disekce
Korean 대동맥의 박리[모든 부분]
Hungarian Aorta dissectio, Aorta aneurysma repedés, nem meghatározott elhelyezkedésű
Sources
Derived from the NIH UMLS (Unified Medical Language System)


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