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Lead II is primarily used to assess the rhythm and rate of the heart because it provides the clearest view of the electrical activity as it travels through the atria and ventricles. This lead is positioned such that it captures the heart’s electrical activity in a way that aligns closely with the heart’s natural axis of electrical conduction.

When monitoring heart rhythms, especially during an electrocardiogram (ECG), Lead II often displays a prominent P wave followed by a QRS complex and T wave. This allows clinicians to easily observe changes in rhythm, such as arrhythmias, and to determine the heart rate. Its effectiveness is due to its specific placement from the right arm to the left leg, making it an optimal choice for identifying the overall pattern of heartbeats.

Other leads may provide valuable information as well, but they do not typically offer the same clarity or reliability for rhythm and rate assessment as Lead II does.