What does Lead I measure in an ECG?

Lead I in an ECG measures the voltage difference between the left arm and the right arm. This lead is part of the standard 12-lead ECG system, which records the electrical activity of the heart in different planes of the body.

The measurement taken by Lead I reflects the electrical potential from the right arm electrode to the left arm electrode, providing information about the heart's electrical activity and orientation in the frontal plane. This helps in diagnosing various cardiac conditions by examining the waveform and amplitude of the recorded signals.

Understanding this configuration is crucial because it positions the leads in a way that allows healthcare professionals to interpret the heart's electrical conduction and assess for any abnormalities.