Synopsis
Interpret every 12-lead in a reproducible sequence, identify time-critical patterns and finish with a clinically useful synthesis rather than a list of measurements.
- Start with context: patient, date/time, symptoms and comparison ECG; then verify calibration (usually 25 mm/s and 10 mm/mV), lead placement and artefact.
- RCUK rhythm skeleton: electrical activity, ventricular rate, regularity, narrow/broad QRS, atrial activity, then the P-QRS relationship.
- Rate: regular rhythm about 300 divided by large squares between R waves; irregular rhythm count QRS on a 10-second strip and multiply by 6.
Key red flags
VF/pulseless VT, sustained VT with adverse features, complete/high-grade AV block with instability, or very rapid irregular broad pre-excited AF. Move from interpretation to RCUK treatment immediately.
Investigation priorities
Anchor the ECG to the correct patient and clinical moment.
Management branches
Every ECG, including apparently normal tracings.
- 1. Context and technical quality: patient, time, symptoms, calibration, lead position, artefact and old ECG.
- 2. RCUK rhythm core: electrical activity, ventricular rate, regularity, QRS width, atrial activity, P-QRS relation.
Key medicines
Aspirin for suspected ACS300 mg PO as a single loading dose as soon as possible unless there is clear allergy; document if given before hospital arrival.
Magnesium sulfate for ECG-confirmed torsades context8 mmol magnesium (approximately 2 g magnesium sulfate) IV over 10 minutes.