Acute Aortic Dissection: quick review

20 Jul
Epidemiology
Higher incidence in men (65%) and with increasing age
Mortality for proximal dissections of 26% (surgical treatment) vs. 58% (nonsurgical)
Mortality for distal dissections of 10.7% (medical treatment) vs. 31% (surgical)
Pathophysiology
Repetitive stresses on the layers of aortic wall (intima, media, adventitia) include prolonged hypertension, weak connective tissues (e.g. Ehlers-Danlos), bicuspid aortic valve
-Stressors plus age can lead to pulsatile blood tearing through the intima into the media
Classification
-Stanford:
  • type A (ascending aorta proximal to brachiocephalic artery)
  • type B (descending aorta distal to subclavian artery)
-DeBakey:
  • type I (ascending aorta extends to arch and beyond),
  • type II (confined to ascending aorta),
  • type III (originates and extends in descending aorta)
Presentation
-more often in older men BUT women present more atypically (e.g. mental status changes or CHF)
Classic presentation of tearing sudden chest pain, pulse deficit and/or BP differential, and widened mediastinum on CXR occurs in less than 30%
-In up to 12% thoracic aortic dissections may be painless
-May also present with STEMI (beware, thrombolytics contraindicated in these cases), syncope, stroke, mesenteric ischemia
Work-up
ECG usually normal or non-specific (e.g. LVH)
CXR most common findings = widened mediastinum and abnormal aortic contour
TEE, CT, MRI all have similar sensitivities
-TEE may be better for unstable patient but cannot visualize entire aorta (e.g. branches of arch and distal ascending)
-CT requires transfer to radiology and exposure to contrast/radiation
Management
-In ED includes pain control, BP and HR control
Target SBP 100-120 mmHg and HR < 60 bpm
-First choice = IV beta-blockers (e.g. esmolol, labetalol)
-Vasodilators (e.g. nitroglycerin) alone can cause reflex tachycardia leading to increased shear forces, so usually used as adjunct if SBP still uncontrolled after beta blocker
Type A dissection: emergent surgery
Type B dissection: less clear optimal treatment BUT medical management can reduce mortality to 10%
Surgery for type B indicated if ongoing pain, refractory HTN, leaking/rupture, occlusion of major arterial trunks, local aneurysms
-Long-term beta blockers for all
 
Submitted by F. DiFranco.

Reference(s): Upadhye S & Schiff K. Acute aortic dissection in the emergency department: diagnostic challenges and evidence-based management. Emergency Medicine Clinics of North America. 30 (2012), 307-327.; picture: Fig 1 from same article.

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