Synopsis
Connect urgent electrocardiographic patterns with the patient’s circulation, identify when electrical treatment is required, and avoid dangerous drug choices in conduction disease and metabolic arrhythmias.
- Check for a pulse and clinical instability before selecting a rhythm-specific treatment.
- Treat sinus tachycardia by correcting its cause; do not cardiovert a compensatory sinus response.
- Use synchronised cardioversion for an unstable tachyarrhythmia with a pulse, with appropriate sedation when feasible.
Investigation priorities
Define the arrhythmia and retain a record for specialist review.
Management branches
An abnormal fast rhythm is accompanied by shock, ischaemia or severe cardiac failure.
- Call senior resuscitation support, secure monitoring and access, and confirm that the rhythm is an arrhythmia rather than compensatory sinus tachycardia.
- Prepare synchronised shocks with sedation or anaesthesia for a conscious patient when feasible, checking that synchronisation markers align with R waves before delivery.
Key medicines
Atropine for appropriate symptomatic bradycardiaGive 500 micrograms IV initially, repeating every 3–5 minutes when necessary to a total dose of 3 mg, while reassessing perfusion and preparing escalation.Do not administer in high-degree AV block with a wide QRS or in a transplanted heart. Ineffectiveness must not postpone pacing or expert alternative treatment.
Calcium gluconate for hyperkalaemic ECG toxicityFor hyperkalaemic ECG toxicity outside cardiac arrest or peri-arrest, give 30 mL of 10% calcium gluconate IV over 10 minutes with ECG monitoring; reassess for further calcium if abnormalities persist or recur.Thirty millilitres of 10% gluconate provides calcium comparable to 10 mL of 10% chloride. Neither salt lowers potassium; monitor the cannula and avoid extravasation.