Which of the patient's limbs usually serves as an electrical ground during an ECG?

In an electrocardiogram (ECG), the right leg is typically used as the electrical ground lead. Utilizing the right leg as a ground helps to minimize electrical interference and noise during the recording process, allowing for a clearer and more accurate representation of the heart's electrical activity. This is crucial as it ensures that the electrodes applied to the other limbs can capture the heart's signals without being affected by extraneous electrical activity commonly present in the environment.

The other limbs have specific roles in the lead placements that measure the heart's electrical signals. The left arm and right arm leads help create biphasic waveforms that reflect the electrical impulses traveling through the heart. The left leg also serves as an active lead in some configurations but is not utilized as the grounding point. Hence, the right leg’s role in grounding is essential for the overall quality and reliability of the ECG results.