10/11/2025
Cardiac Axis
Use the “Thumb Rule” (LIT) — Left thumb = Lead I, Right thumb = aVF.
Imagine you’re giving a thumbs-up with both hands.
✅ 1. Normal Axis (–30° to +90°)
👉 Lead I positive
👉 aVF positive
✅ Both thumbs UP = NORMAL
✅ 2. Left Axis Deviation (LAD) (–30° to –90°)
👉 Lead I positive
👉 aVF negative
✅ Left thumb UP, right thumb DOWN = LAD
🧠 Think: “Left positive → Left axis”
✅ 3. Right Axis Deviation (RAD) (+90° to +180°)
👉 Lead I negative
👉 aVF positive
✅ Left thumb DOWN, right thumb UP = RAD
🧠 “Right positive → Right axis”
✅ 4. Extreme Axis (Northwest axis) (–90° to 180°)
👉 Lead I negative
👉 aVF negative
✅ Both thumbs DOWN = BAD / EXTREME axis
Easy memory: “Double Down = Dangerous Direction”
✅ Ultra-Short Formula
✅ I +, aVF + → NORMAL
✅ I +, aVF – → LAD
✅ I –, aVF + → RAD
✅ I –, aVF – → EXTREME