ST elevation in II, III and aVF, with reciprocal ST depression in aVL.
Inferior wall injury comes from an occlusion of the right coronary artery (80%) or the circumflex (18%). You see ST elevation in II, III and aVF, and reciprocal depression in aVL, the one lead truly opposite the inferior wall (often in I too). Right coronary: elevation in III greater than II, with depression in I. Circumflex: II about equal to III, no depression in I, and sometimes elevation in I, aVL or V5-V6. Look for right ventricular involvement (40%) and AV block (20%).
Each is a standard 12-lead: 2.5 seconds of each lead in four columns, with 10 seconds of lead II along the bottom, drawn to scale (25 mm a second, 10 mm a millivolt). The measurements are under each one.
An inferior STEMI with III elevated more than II, ST elevation in V1, and ST elevation in the right-sided lead V4R.
Horizontal ST depression in V1-V3 with tall R waves and upright T waves, and ST elevation in the posterior leads V7-V9.
ST elevation in I, aVL, V5 and V6, with reciprocal depression in III and aVF.
The ECG tool in the app gives you a new 12-lead every time and walks you through reading it: rate, QRS, axis, then where the ST is up and down. It's part of the Paramedic level, and you can try 5 ECGs a day free.
Try the 12-lead drill
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