Tachycardia (wide)

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Background

  • 3 wide complexes in a row is considered ventricular tachycardia; non-sustained if lasts less than 30 seconds
  • Sustained ventricular tachycardia is ventricular tachycardia >30 seconds

Etiology[1][2][3]

  • WCT is due to true ventricular tachycardia in 80% of cases
  • For patients with underlying cardiac disease, this number increases to > 90%
  • Multiple other causes must be considered, including Hyperkalemia, Digoxin toxicity, severe metabolic acidosis, and others

Differential Diagnosis

Regular

Irregular

  • A-fib/flutter w/ variable AV conduction AND BBB (fixed or rate-related)
  • A-fib/flutter w/ variable AV conduction AND accessory pathway (eg WPW)
  • A-fib + Hyperkalemia
  • Polymorphic v-tach/torsades

Evaluation

Ventricular tachycardia
  • Assume ventricular tachycardia until proven otherwise
  • See V Tach vs. SVT

Management

Pulseless: see Adult pulseless arrest

Unstable

  • Regular: Synchronized cardioversion 100-200J
  • Irregular: Unsynchronized cardioversion (defibrillation) 200J

Stable

  • Procainamide 100 mg q5min at max rate of 25-50 mg/min[4]
    • Until termination of arrhythmia, then start 2-6 mg/min (or 1-2 mg/min for renal/cardiac failure) OR
    • Max 17 mg/kg total dose given (12 mg/kg if renal failure) OR
    • If QRS widens > 50%
  • Amiodarone, agent of choice in setting of AMI or LV dysfunction
    • 150 mg over 10min (15 mg/min), followed by 1 mg/min drip over 6hrs (360 mg total)[5]
    • Then 0.5 mg/min drip over next 18 hrs (540 mg total)
    • Oral dosage after IV infusion is 400 -800 mg PO daily
  • Lidocaine 1-1.5mg/kg IV q5min, repeat PRN until up to 300mg/hr

Recurrent

  • ≥3 episodes within 24 hours considered electrical storm and may require alternate treatment (i.e. beta blockade, sedation, ablation)

Other considerations

  • True Vtach generally has rate >120bpm. If rate <120bpm or refractory to other therapy, consider other causes
  • When in doubt, use cardioversion for treatment of regular WCT. In irregular WCT, consider Afib with WPW in which Procainamide is the treatment of choice.
  • In very wide complex (>0.2 msec) and <120 bpm in a patient with significant history, consider giving calcium chloride to treat hyperkalemia
  • Consider Acidosis
  • Sodium channel blockade (e.g. from benadryl, TCA, or cocaine toxicity) may cause very wide complex (>0.2msec) tachycardia with rate <120bpm

Disposition

  • Admit all patients (even if converted to NSR in ED)

See Also

References

  1. Gupta AK, Thakur RK. Wide QRS complex tachycardias. Med Clin North Am. 2001;85(2):245–66– ix–x.
  2. Akhtar M, Shenasa M, Jazayeri M, Caceres J, Tchou PJ. Wide QRS complex tachycardia. Reappraisal of a common clinical problem. Ann Intern Med. 1988;109(11):905–912.
  3. Stewart RB, Bardy GH, Greene HL. Wide complex tachycardia: misdiagnosis and outcome after emergent therapy. Ann Intern Med. 1986;104(6):766–771.
  4. Procainamide. GlobalRPH. http://www.globalrph.com/procainamide_dilution.htm.
  5. Amiodarone. GlobalRPH. http://www.globalrph.com/amiodarone_dilution.htm.