What does lead I record between?

Lead I records the electrical activity of the heart between the left arm and the right arm. This lead is part of a standard 12-lead electrocardiogram (ECG), which helps in assessing the heart's rhythm and detecting any abnormalities in its electrical activity.

When electrodes are placed on the torso, Lead I measures the potential difference between the left arm electrode and the right arm electrode. The orientation of this lead provides valuable information about the heart's electrical axis in the frontal plane. By focusing on this specific axis, clinicians can identify certain types of arrhythmias, conduction blocks, and other cardiovascular problems.

The placement and function of other leads differ in their measurements, as they connect to different parts of the body or utilize different combinations of limb electrodes to capture the heart's activity from various angles, highlighting the importance of proper lead placement in an ECG for accurate diagnosis and monitoring.