Unstable Tachycardia

Synchronised DC cardioversion

Red flags
  • Chest pain, shock, HF, altered mental state = adverse signs
  • Pulseless → follow VF/VT arrest algorithm
  • Torsades → Mg 2 g IV

First steps

  • ABCDE + attach defib pads
  • IV access
  • Sedate if conscious (midazolam ± fentanyl)

Key investigations

  • 12-lead ECG (rhythm identification)
  • K+, Mg, troponin

Differentials

  • VT vs SVT with aberrancy
  • AF with WPW (irregular wide)

Initial management

  • Narrow: sync shock 50-100 J; AF 120-200 J; flutter 70-120 J
  • Wide (VT): 100-200 J biphasic
  • Post-conversion: amiodarone 300 mg IV over 20 min then 900 mg/24 h
  • Correct K+ >4.5, Mg >1

Referral

  • Cardiology / EP for ablation or ICD assessment
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WardRound

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