leadII

Lead II is one of the standard limb leads used in electrocardiography. It is one of the Einthoven leads (I, II, III) that form the basic framework for recording the heart’s electrical activity. In lead II, the positive electrode is placed on the left leg and the negative electrode on the right arm, with a ground electrode typically placed on the right leg. The frontal-plane electrical axis for this lead is approximately +60 degrees, meaning the measured voltage represents the electrical activity directed from the right arm toward the left leg.

Lead II is widely used for rhythm assessment because its orientation often yields a clear view of the P wave and the QRS complex, making it a common default monitoring lead in both continuous and 12-lead ECG recordings. It is commonly recorded as part of standard ECG procedures and is frequently relied upon for initial rhythm interpretation in emergency and clinical settings.

Interpreting lead II requires proper electrode placement: RA on the right arm, LA on the left arm, LL on the left leg, with the RL electrode serving as the ground. While lead II provides valuable information about conduction and rhythm, comprehensive ECG evaluation typically involves all 12 leads (I, II, III, augmented leads aVR, aVL, aVF, and chest leads V1-V6) to assess cardiac conditions from multiple viewpoints.

Limitations can include electrode misplacement, patient movement, or anatomical variations such as dextrocardia, which can alter the lead’s appearance. Lead II remains a foundational tool for rhythm monitoring and initial assessment in electrocardiography.