1. What is Heart Axis Calculation?

The heart axis calculation determines the mean electrical axis of ventricular depolarization from EKG leads. It helps identify normal conduction patterns and diagnose axis deviations.

2. How Does the Calculator Work?

The calculator uses the following formula:

Where:

• \( Lead\ I \) — Voltage measurement from Lead I (mV)
• \( Lead\ III \) — Voltage measurement from Lead III (mV)
• The result is converted from radians to degrees

Explanation: The calculation uses the arctangent function of the ratio between Lead III and Lead I voltages to determine the electrical axis.

3. Importance of Heart Axis

Details: The heart axis helps diagnose conditions like left axis deviation (LAD), right axis deviation (RAD), and extreme axis deviation, which can indicate various cardiac pathologies.

4. Using the Calculator

Tips: Enter the voltage measurements from Lead I and Lead III in millivolts (mV). The calculator will compute the heart axis in degrees.

5. Frequently Asked Questions (FAQ)

Q1: What is a normal heart axis?
A: Normal axis ranges from -30° to +90°. Left axis deviation is -30° to -90°, right axis deviation is +90° to +180°, and extreme axis deviation is -90° to -180°.

Q2: Why use Lead I and Lead III for axis calculation?
A: These leads form the basis of Einthoven's triangle and provide the most straightforward method for calculating the frontal plane axis.

Q3: How accurate is this calculation?
A: This provides a good estimate of the mean QRS axis, but visual inspection of all leads is needed for precise determination.

Q4: What conditions cause axis deviation?
A: Left axis deviation may occur in left ventricular hypertrophy, while right axis deviation may occur in right ventricular hypertrophy or pulmonary conditions.

Q5: Can this be used for P-wave or T-wave axis?
A: The same principle applies but requires measuring the P-wave or T-wave voltages instead of QRS complexes.