Final answer:
Bipolar lead II in an ECG measures electrical activity of the heart from the right arm to the left leg. It helps to view the depolarization wave moving from the atria to the ventricles during a heartbeat.
Step-by-step explanation:
Bipolar lead II takes a tracing from the right arm (RA) to the left leg (LL). Lead II is one of the standard leads used in an electrocardiogram (ECG), which measures the electrical activity of the heart. The placement of these electrodes allows clinicians to view the heart's electrical activity, particularly the depolarization that spreads from the atria to the ventricles during a heartbeat.
The outer surface of the heart changes from positive to negative during depolarization, captured as a vector in an ECG. This vector points in the direction of the wave of depolarization, and when using bipolar lead II, it ideally shows the electrical activity moving from the upper right portion of the body towards the lower left, closely aligning with the heart's electrical axis. The electrodes RA, LA, and LL, represent the right arm, left arm, and left leg, respectively, and each pair of electrodes form the leads I, II, and III, in an ECG tracing, where Lead II is specifically from RA to LL.