Recording a 12-lead ECG
PLAB 2 & PRES 3 · practical skills / cardiology · medium · 8 minutes
Candidate brief
You are an FY2 doctor in the emergency department. Mr Rajesh Patel, 57, presented an hour ago with central chest pain. He is now pain-free and has had initial bloods and observations. The consultant has asked you to record a 12-lead ECG. Observations: heart rate 78, blood pressure 142/86 mmHg, respiratory rate 16, oxygen saturations 98% on air, temperature 36.9 °C. Please record the ECG, check the quality of the trace, and tell the examiner what you would do with it. Verbalise each step as you perform it.
What examiners look for
An ECG station is marked on placement and quality control, not on cardiology knowledge. The examiner is watching whether you count intercostal spaces — V1 and V2 placed one space too high is the single commonest technical error, and it manufactures abnormal-looking complexes that have sent real patients down false pathways. Skin preparation is diagnosis protection. Electrodes floated on hair produce wander and artefact; a trace full of artefact in a man with chest pain will be repeated anyway, so the two minutes spent cleaning, drying and shaving small patches are the fastest route to a usable tracing. Learn the two reversal/malposition signatures cold: limb-lead reversal gives a negative lead I with a positive aVR and an otherwise "impossible" picture; high V1/V2 mimics anterior problems. Recognising a technical error aloud is senior behaviour — misdiagnosing one is the opposite. Standardisation is what makes serial ECGs comparable: same positions, 25 mm/s, 10 mm/mV, and the time written on the trace. In suspected ACS, the change between traces is often the diagnosis; an unlabelled, untimed trace cannot be compared. Answer his question straight: the ECG may show a heart attack, but a normal one does not exclude it. Candidates who over-reassure here ("it's normal, so your heart is fine") commit the station's most dangerous error — troponin and serial ECGs exist precisely because one tracing is not enough. The recording is not finished when it prints. It is finished when a senior has seen it. In chest-pain pathways, the ECG's destination is a decision-maker, not a notes folder.
Guideline references
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