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ECG Heart Axis Calculator

Determine cardiac electrical axis using limb lead polarity

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Educational Use Only: This tool is for educational purposes only. It does not replace clinical judgment or medical advice.

1. Look at the main QRS deflection in Lead I

2. Look at the main QRS deflection in Lead aVF

3. Use the table below to determine axis

• Normal: Lead I (+), aVF (+) → 0° to +90°

• Left Deviation: Lead I (+), aVF (-) → -30° to -90°

• Right Deviation: Lead I (-), aVF (+) → +90° to +180°

• Extreme Deviation: Lead I (-), aVF (-) → -90° to +180°

Cardiac axis reflects the overall direction of electrical depolarization and can indicate various pathological conditions.

Left axis deviation: Often seen in left anterior fascicular block, left ventricular hypertrophy, or inferior wall MI.

Right axis deviation: May indicate right heart strain, pulmonary embolism, or lateral wall MI.

Master your skills with interactive cases, real-time simulations, and expert-guided learning in the E-PulsePoints mobile app.