tachyarrhythmia (tachycardia)

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[1][2][3]

Introduction

Tachycardia is defined as a heart rate in excess of 100/min.

Classification

  • tachycardias may be classified as supraventricular (SVT) or ventricular (VT) depending of the origin of the initial depolarization
  • this distinction is important since the prognosis & therapeutic modalities differ
  • initial evaluation may only characterize the tachyarrhythmia as narrow complex (QRS <120 ms) or wide complex (QRS >120 ms)

Laboratory

Diagnostic procedures

Management

Caveat

  • may be difficult to distinguish cardiogenic tachycardia (suppress) from tachycardia due to physiological needs (allow)
  • assess intravascular volume & other noncardiac determinants of a rapid ventricular response prior to treatment[2] 
           ALGORITHM FOR MANAGEMENT OF TACHYCARDIA
  • Hemodynamically unstable
    • signs/symptoms related to tachycardia
      • hypotension
      • congestive heart failure
      • altered mental status
      • ischemic chest pain
      • myocardial infarction
    • ventricular rate > 150 & rhythm not sinus tachycardia
    • immediate cardioversion
  • Hemodynamically stable
    • atrial flutter or fibrillation
      • calcium channel blocker
        • verapamil
        • diltiazem
      • beta blocker
      • digoxin
    • paroxysmal supraventricular tachycardia (PSVT)
      • consider vagal maneuvers
        • carotid sinus massage is most common maneuver, contraindicated in elderly & patients with carotid bruits, bilateral carotid sinus massage should never be performed
      • adenosine 6 mg IV push, if no response in 1-2 min, 12 mg IV push (may repeat once)
      • normal or elevated blood pressure
        • verapamil 2.5-5 mg IV, then 5-10 mg IV
        • diltiazem
        • beta-blocker
        • digoxin
        • synchronized cardioversion
      • low or unstable blood pressure
        • synchronized cardioversion
    • wide-complex tachycardia of uncertain type
      • lidocaine 1.0-1.5 mg/kg IV, then 0.5-0.75 mg/kg pushevery 5-10 min for max of 3 mg/kg, if successful start infusion at 2-4 mg/min
      • adenosine 6 mg IV push, if no response in 1-2 min, 12 mg IV push (may repeat once)
      • procainamide 20-30 mg/min IV for a maximum of 17 mg/kg
      • synchronized cardioversion
    • ventricular tachycardia
      • lidocaine 1.0-1.5 mg/kg IV, then 0.5-0.75 mg/kg push every 5-10 min for max of 3 mg/kg, if successful start infusion at 2-4 mg/min
      • procainamide 20-30 mg/min IV for a maximum of 17 mg/kg
      • synchronized cardioversion

More general terms

More specific terms

References

  1. ↑ ACLS - The Reference Texbook ACLS: Principles & Practice, Cummins RO et al (eds), American Heart Association, 2005 http://www.americanheart.org/cpr
  2. ↑ 2.0 2.1 Scheuermeyer FX et al. Emergency department patients with atrial fibrillation or flutter and an acute underlying medical illness may not benefit from attempts to control rate or rhythm. Ann Emerg Med 2014 Nov 6 <PubMed> PMID: https://www.ncbi.nlm.nih.gov/pubmed/25441768 <Internet> http://www.annemergmed.com/article/S0196-0644%2814%2901298-0/abstract
  3. ↑ 3.0 3.1 3.2 Medical Knowledge Self Assessment Program (MKSAP) 17, American College of Physicians, Philadelphia 2015
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