SVT: narrow, regular, fast. VT: wide. WPW: delta wave, short PR
ABCDE Assess stability; unstable → synchronised DCCV (pulseless VT → defibrillate); correct electrolytes.
Calculators: qtc
Check first: Ca, Mg, K, O2 levels (low levels provoke arrhythmia)
SVT (stable): Vagal / carotid massage → Adenosine 6 mg → 12 mg IV push → if fails, diltiazem/verapamil IV bolus
VT (stable, normal BP): IV procainamide or amiodarone 150 mg IV over 10 min (co-equal — PROCAMIO favored procainamide; sotalol removed from 2025 AHA algorithm)
VT unstable / hypotension → synchronized cardioversion (narrow-complex 100 J; monomorphic VT 100 J; AF/AFL 200 J; polymorphic VT → unsynchronized defibrillation dose); pulseless → defibrillate
WPW with AF: Procainamide 20–50 mg/min IV (best)
Decision tree Pulse present?
Yes Haemodynamically stable?
Yes Narrow complex (SVT)?
Yes Vagal → adenosine → AV-nodal blocker
No VT: procainamide or amiodarone (avoid AV-nodal blockers if WPW)
No Synchronised cardioversion
No Defibrillate + ALS (pulseless VT/VF)
Order set ECG (12-lead) + rhythm strip K⁺, Mg, Ca Continuous monitoring Pads on Criteria Admit Sustained/haemodynamically significant arrhythmia
ICU Recurrent VT/instability, post-arrest
Intubate Post-arrest / peri-arrest
Discharge Rhythm controlled, electrolytes corrected, EP referral
Never Give AV-nodal blockers (adenosine, digoxin, β-blocker, verapamil) in WPW+AF → VF Transfer an unstable patient elsewhere Key Ablation is curative for recurrent SVT/WPW. Clinical detail — differentials, red flags, pitfalls, disposition Red flags Instability → synchronised DCCV Pulseless VT → defibrillate Differentials Sinus tachycardia AF/flutter with aberrancy Artefact Common mistakes AV-nodal blockers in WPW+AF Treating VT as SVT Disposition & follow-up EP referral; consider ablation/ICD.
Discharge package Medications As indicated; avoid AV-nodal blockers in WPW
Follow-up Electrophysiology; consider ablation/ICD
Warning symptoms Palpitations with syncope, chest pain
💊 Treatment detail — doses & preparation Adenosine antiarrhythmic
Dose 6 mg rapid IV push → 12 mg → 12 mg if no response
Preparation Push undiluted (3 mg/mL) fast via proximal port, immediate 20 mL flush, raise arm
Monitor Transient asystole/flushing expected; avoid in WPW+AF, asthma caution
Diltiazem non-DHP CCB
Dose IV 0.25 mg/kg over 2 min, then 5–15 mg/h; PO 60–120 mg TDS (MR OD available)
Preparation IV 25 mg in 5 mL undiluted or in 100 mL NS; infusion 125 mg in 500 mL NS
Monitor HR, BP, AV block; avoid in HFrEF/WPW
Amiodarone IV antiarrhythmic
Dose Arrest: 300 mg IV/IO bolus (then 150 mg). Stable: 150 mg over 10 min, then 1 mg/min ×6 h, 0.5 mg/min ×18 h
Preparation Bolus 300 mg in 20–50 mL D5W; infusion 900 mg in 500 mL D5W (glass/non-PVC)
Monitor QT, LFTs, thyroid; long half-life — interacts with warfarin/digoxin
Procainamide IV class Ia antiarrhythmic
Dose Stable monomorphic VT or WPW+AF: 20–50 mg/min IV until arrhythmia suppressed, hypotension, QRS widens >50%, or max 17 mg/kg; then 1–4 mg/min
Preparation 100 mg/mL vial; infuse via pump with continuous ECG + BP monitoring
Monitor Hypotension, QRS/QT widening; avoid in prolonged QT/HFrEF caution; co-equal with amiodarone for stable VT (2025 AHA)
Magnesium sulfate IV electrolyte/antiarrhythmic
Dose Torsades: 2 g over 10–15 min. Asthma: 2 g over 20 min. Eclampsia: 4 g load then 1 g/h
Preparation 2 g in 100 mL NS via pump; eclampsia 4 g in 100–200 mL
Monitor Reflexes/RR if high doses (toxicity), Mg²⁺ level, renal function
📖 ESC / AHA-ACC-HRS Arrhythmias Reviewed July 2026