ECG Leads and What They Show
ECG leads work like different cameras capturing your heart's electrical activity from various angles. Standard limb leads (I, II, III) form Einthoven's triangle, with the right arm electrode always negative and left leg electrode always positive.
Lead I records between left arm (+) and right arm (-), viewing the lateral wall of your left ventricle. Lead II records between left leg (+) and right arm (-), showing the inferior surface. Lead III records between left leg (+) and left arm (-), also viewing the inferior surface.
The augmented limb leads (aVR, aVL, aVF) provide additional perspectives. aVL views from the left arm toward the lateral wall, aVR from the right shoulder (usually showing negative waveforms), and aVF from the left foot/leg toward the inferior surface.
📝 Quick Tip: Think of leads as different camera angles around your heart. Each lead captures a unique view, helping doctors spot problems that might only be visible from certain directions.