Which lead records electrical activity from the right arm to the left arm?

• A. Lead I
• B. Lead II
• C. Lead III
• D. aVR

Answer: (A)

Lead I is designed to record the electrical activity of the heart from the right arm to the left arm. In this particular configuration, the right arm electrode serves as the negative pole, while the left arm electrode functions as the positive pole. As the heart generates electrical impulses, the potential difference between these two electrodes is captured, allowing Lead I to provide a visual representation of the heart's electrical activity in a lateral direction.

This lead is particularly useful in assessing the heart's overall rhythm and orientation in the frontal plane. The ECG tracing from Lead I can help healthcare professionals detect various cardiac issues, such as arrhythmias and conduction abnormalities. The orientation and placement of the electrodes in Lead I are integral to its ability to provide valuable diagnostic information.