Describes how to determine the electrical axis of the heart using the 12-lead ECG. Illustrates six frontal plane lead positions and charges using original graphics. Identifies vector direction, based on QRS deflection, and presents a method to calculate its net deflection. Demonstrates the step-by-step process to determine electrical axis using actual ECGs and discusses causes of axis deviation. Emphasizes patient assessment, accurate documentation and comparison of ECG findings in the evaluation of axis deviation.