ICU Basics

Cardiac arrest and ACLS

VT Storm Algorithm

Recurrent VT or VF and repeated ICD shocks

Reviewed by Alex G, BSN, RN, CEN, CCRN, CMC, NREMT-P · From the Reference tab of the app

Each step lists what to do, then the choices that lead on. In the app the algorithm is tapped through one decision at a time.

1 Electrical storm: call for help, pads on

  • Storm: 3 or more episodes of sustained VT or VF in 24 h, at least 5 min apart, each needing a shock, pacing or drug to stop it
  • Call the provider and cardiology or electrophysiology (EP); code team to the bedside if unstable
  • Pads on (at least 8 cm from an ICD generator), continuous ECG, a 12-lead of each episode, IV access, arterial line
  • Stat K⁺, Mg²⁺, ionized Ca, troponin and a blood gas; list QT-prolonging and proarrhythmic drugs

Pulseless VT or VF now → step 2VT with a pulse, unstable → step 3ICD firing again and again → step 4Stable, or between episodes → step 5

2 Pulseless: CPR and defibrillate

  • Adult arrest algorithm: shock, CPR, epinephrine; amiodarone 300 mg (then 150 mg) or lidocaine 1–1.5 mg/kg
  • ICD present: shock externally anyway; do not wait for the device
  • Refractory VF: think ischemia (emergent cath) and ECPR where a trained team exists

ROSC → step 5

3 Unstable with a pulse: shock now

  • Monomorphic VT: synchronized cardioversion 100 J, then higher; sedate if time allows
  • Polymorphic VT: defibrillate (unsynchronized); always treat it as unstable
  • Re-press SYNC before each repeat cardioversion

Back in a perfusing rhythm → step 5

4 ICD shocks: appropriate or not?

  • Read the monitor before each shock: VT or VF means appropriate; sinus, AF or noise means inappropriate
  • Call EP or the device team to interrogate the ICD now

Appropriate: real VT or VF → step 5Inappropriate: sinus, AF or lead noise → step 6

5 Fix electrolytes and remove triggers

  • Keep K⁺ 4.0–5.0 mEq/L (4.5–5.0 with a long QT) and Mg²⁺ 2.0 mg/dL or more
  • KCl up to 10 mEq/h peripheral or 20 mEq/h central per policy; magnesium sulfate 2 g IV over 15 min if low
  • Stop QT-prolonging and proarrhythmic drugs; wean inotropes if possible
  • Treat triggers: ischemia, heart failure, hypoxemia, fever, thyrotoxicosis, pain and fear

Next: what does the VT look like? → step 7

6 Inappropriate shocks: magnet

  • With the provider: a magnet over the generator suspends shocks and anti-tachycardia pacing while it stays on
  • Bradycardia pacing continues in most ICDs
  • Pads on and continuous monitoring: external shocks for any VT or VF
  • Treat the cause (AF rate control, lead fracture); the device team reprograms or revises the lead

End of this path.

7 What does the VT look like?

  • Compare the 12-leads of each episode
  • Measure the QTc between episodes

Monomorphic VT → step 8Polymorphic VT with a long QT (torsades) → step 9Polymorphic VT or VF with a normal QT → step 10

8 Monomorphic VT: amiodarone, then lidocaine

  • Amiodarone 150 mg IV over 10 min, repeated for recurrence; then 1 mg/min for 6 h, then 0.5 mg/min (about 2.2 g a day at most)
  • Still recurring: add lidocaine 1–1.5 mg/kg IV, then 1–4 mg/min (rebolus 0.5–0.75 mg/kg, total bolus 3 mg/kg)
  • Scar VT often needs ablation: involve EP early

Next: calm the sympathetic drive → step 11

9 Torsades (polymorphic VT with a long QT)

  • Magnesium sulfate 2 g IV over 15 min whatever the level; repeat once if it recurs
  • K⁺ 4.5–5.0; stop every QT-prolonging drug (antiarrhythmics, haloperidol, ondansetron, macrolides, methadone)
  • Recurs after pauses or slow rates: isoproterenol 2–10 mcg/min or overdrive pacing to a rate over 70/min (AHA/ACCF 2010), often 90–110
  • No amiodarone or procainamide: both lengthen the QT

Settled → step 12Still recurring → step 13

10 Polymorphic VT with a normal QT: ischemia until proven otherwise

  • 12-lead between episodes and troponin; cardiology for emergent coronary angiography
  • Amiodarone as for monomorphic VT; lidocaine is a useful add-on in ischemia
  • Cardiogenic shock: mechanical support with the shock team
  • No ischemia: think Brugada (coved ST in V1–V2, fever), drug toxicity or PVC-triggered VF; EP

Next: calm the sympathetic drive → step 11

11 Calm the sympathetic storm

  • Beta-blocker with the amiodarone unless in shock: propranolol (non-selective, preferred) 40 mg every 6 h by mouth or tube
  • IV: propranolol 1–3 mg at no more than 1 mg/min (repeat once after 2 min), or esmolol 500 mcg/kg over 1 min, then 50–200 mcg/kg/min
  • Borderline BP: esmolol, which wears off within about 20 minutes of stopping
  • Mild to moderate sedation with analgesia (for example small doses of midazolam and fentanyl) to ease fear and sympathetic drive

Next: is it settling? → step 14

12 Storm controlled: prevent the next one

  • CCU or ICU monitoring; continue amiodarone and the beta-blocker; keep K⁺ and Mg²⁺ in range
  • ICD interrogation and reprogramming (more anti-tachycardia pacing, longer detection) by the device team
  • EP plans ablation; treat ischemia, heart failure and drug causes
  • Repeated shocks are frightening: explain, support and screen for distress

End of this path.

13 Refractory storm: escalate

  • Intubate and sedate deeply (for example propofol) to cut sympathetic drive
  • Urgent catheter ablation by EP, the definitive treatment for recurrent monomorphic VT
  • Bridge: stellate ganglion block with local anesthetic (anesthesia) or a thoracic epidural
  • Cardiogenic shock: VA-ECMO or Impella with the shock team, as a bridge to ablation

Storm controlled → step 12

14 Still recurring despite drugs and sedation?

  • Count episodes and shocks over the last hour
  • Recheck K⁺, Mg²⁺ and the QTc

Settling → step 12Still recurring → step 13

Drugs in this algorithm

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