Nontraumatic thoracic aortic dissection

(Redirected from Aortic dissection)

Not to be confused with traumatic aortic transection

Background

Aortic sebments.
Branches of the aorta.
  • Most commonly seen in men 60-80 yrs old
  • Intimal tear with blood leaking into media
  • Mortality increases 1% per hour of symptoms when untreated
  • Diagnosis delayed > 24hr in 50% of cases
  • Bimodal age distribution

Clinical Features

General

  • Symptoms
    • Tearing/ripping pain (10.8x increased disease probability)
      • 64% described the pain as sharp vs 50.6% who described it as tearing or ripping[1]
    • Migrating pain (7.6x)
    • Sudden chest pain (2.6x)
    • History of hypertension (1.5x)
  • Signs

Specific

Differential Diagnosis

Chest pain

Critical

Emergent

Nonemergent

Hypertension

Evaluation

Aortic Dissection Detection Risk Score (ADD-RS)

A score 1 should be awarded for each of the 3 categories that contain at least one of the listed features

Predisposing conditions Pain features Physical findings

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 neurological 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%

No Risk Factor Screening

  • CXR
    • Abnormal in 90% (3.4x)
    • Mediastinal widening (seen in 56-63%)
    • Left sided pleural effusion (seen in 19%)
    • Widening of aortic contour (seen in 48%), displaced calcification (6mm), Calcium sign (look for white line of calcium within aortic knob and measure to outer edge of the aortic knob - distance greater than 0.5 cm is positive and > 1 cm is highly suspicious for dissection), aortic kinking, double density sign
CXR showing widened mediastinum and porminent aortic knob

Low-Intermediate (Based on ADD-RS)[4][5][6]

  • D-dimer for ADD-RS ≤ 1 (low or intermediate risk)

High Risk/Definitive

CT chest with contrast of thoracic aortic dissection.
  • CT aortogram chest
    • Study of choice
    • Similar sensitivity/specificity to TEE and MRA

Other Findings

Type A Aortic Dissection[7]
Abdominal Aortic Dissection on Ultrasound
  • ECG
    • LVH on admission ECG (3.2x)
    • Ischemia (esp inferior) - 15%
    • Nonspec ST-T changes - 40%
  • Bedside US
    • Can help in ruling in patients when AOFT is >4cm
    • Rule out pericardial effusion and tamponade, especially in hypotension, syncope, dyspnea
    • TEE has a sensitivity of 98% and 95% specific[8]

Classification (Stanford)

  • Type A
    • Involves any portion of ascending aorta
  • Type B
    • Isolated to descending aorta
Classification of aortic dissection
Image AoDissect DeBakey1.png AoDissect DeBakey2.png AoDissect DeBakey3.png
Percentage 60% 10–15% 25–30%
Type DeBakey I DeBakey II DeBakey III
Classification Stanford A (Proximal) Stanford B (Distal)

Management

Lower wall tension by lowering BP (La Place T = P × r)

  • Important considerations
    • Right radial arterial line or right arm blood pressure will be the most accurate
    • Beta blockers are good first-line options, since they reduce heart rate and aortic wall tension
    • It is important to provide adequate analgesia in order to decrease sympathetic output leading to tachycardia and hypertension
  1. Heart rate control (beta-blockers are first line)

Heart Rate control

Control heart rate before blood pressure (Goal to keep HR <60 bpm and SBP 100-120)[9]
  1. Esmolol
    • Advantage of short half life, easily titratable
    • Bolus 0.5mg/kg over 1min; infuse 0.05mg/kg/min (titrate upward in 0.05mg/kg/min increments to a maximum of 0.3 mg/kg/min)
    • Esmolol Drip Sheet
  2. Labetalol - has both α and beta effects
    • Push dose - 10-20mg with repeat doses of 20-40mg q10min up to 300mg
    • Drip - Load 15-20mg IV, followed by 5mg/hr
  3. Metoprolol
    • 5mg IV x 3; infuse at 2-5mg/hr
  4. Diltiazem - Use if contraindications to beta-blockers
    • Loading 0.25mg/kg over 2–5 min, followed by a drip of 5mg/h

Blood pressure control (vasodilators)

    • Do not control blood pressure without adequate heart rate control (must suppress reflex tachycardia which will shear forces from increased HR)
  2. Nicardipine/Clevidipine - consider following regimen for nicardipine:
    • 5mg/hr start, then titrate up by 2.5mg/hr every 10 min until goal
    • Once at goal, drop to 3mg/hr and re-titrate from there
    • May initially bolus 2mg IV[10]
  3. Nitroprusside 0.3-0.5mcg/kg/min - Risk of cerebral blood vessel vasodilation and CN/Thiocynate toxicity
  4. Fenoldopam
  5. Enalapril
  6. Analgesia

Surgery

  • Type A (any portion of ascending aorta)
    • Requires surgery
  • Type B (isolated to descending aorta)
    • Primarily medical management with surgery consultation

Disposition

  • Admission to OR or ICU

Complications

  • AV Regurgitation/Insufficiency
    • CHF with diastolic murmur
  • Rupture
  • Vascular obstruction
    • Coronary: ACS
    • Carotid: CVA
    • Lumbar: Paraplegia

See Also

External Links

References

  1. ↑ 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.
  2. ↑ 2.0 2.1 2.2 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.
  3. ↑ Spittell PC, S et al. Clinical features and differential diagnosis of aortic dissection: experience with 236 cases (1980 through 1990) Mayo Clin Proc. 1993;68:642–51.
  4. ↑ Circulation. 2018 Jan 16;137(3):250-258. doi: 10.1161/CIRCULATIONAHA.117.029457. Epub 2017 Oct 13. Nazerian, et al. Diagnostic Accuracy of the Aortic Dissection Detection Risk Score Plus D-Dimer for Acute Aortic Syndromes: The ADvISED Prospective Multicenter Study.
  5. ↑ Asha SE et al. "A systematic review and meta-analysis of D-dimer as a rule out test for suspected acute aortic dissection." Annals of EM. 66;4;368-377Ocotber 2015.
  6. ↑ Shimony A, et al. Meta-analysis of usefulness of d-dimer to diagnose acute aortic dissection. Am J Cardiol. 2011; 107(8):1227-1234.
  7. ↑ http://www.thepocusatlas.com/echocardiography-1
  8. ↑ Shiga T, Wajima Z, Apfel CC, Inoue T, Ohe Y. Diagnostic accuracy of transesophageal echocardiography, helical computed tomography, and magnetic resonance imaging for suspected thoracic aortic dissection: systematic review and meta-analysis. Arch Intern Med. 2006 Jul 10;166(13):1350-6.
  9. ↑ Tsai TT, Nienaber CA, and Eagle KA. Acute Aortic Syndromes. Circulation. 2005;112:3802–3813
  10. ↑ 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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