Lead positioning

	3-electrode system - Uses 3 electrodes (RA, LA and LL). - Monitor displays the bipolar leads (I, II and III) - To get best results – Place electrodes on the chest wall equidistant from the heart (rather than the specific limbs)
	5-electrode system - Uses 5 electrodes (RA, RL, LA, LL and Chest) - Monitor displays the bipolar leads (I, II and III) - AND a single unipolar lead (depending on position of the brown chest lead (positions V1–6))
	12-lead ECG - 10 electrodes required to produce 12-lead ECG. - – Electrodes on all 4 limbs (RA, LL, LA, RL) - – Electrodes on precordium (V1–6) - Monitors 12 leads (V1–6), (I, II, III) and (aVR, aVF, aVL) - Allows interpretation of specific areas of the heart - – Inferior (II, III, aVF) - – Lateral (I, aVL, V5, V6) - – Anterior (V1–4)

The ECG is one of the most useful investigations in medicine. Electrodes attached to the chest and/or limbs record small voltage changes as potential difference, which is transposed into a visual tracing

ECG electrode system

ECG Academy Videos

The ECG Lead

The Limb Leads

The Precordial Leads

Further Reading

• ECG BASICS – Waves, Intervals, Segments and Clinical Interpretation
• ECG CLINICAL CASES – Your favourite ECG’s placed in clinical context with a challenging Q&A approach
• ECG and Cardiology Eponymous Syndromes – Cheats guide to eponymous emancipation
• ECG Reference Sites on the WEB – the best of the rest

Author Credits