Which lead in an ECG is typically used to monitor cardiac rhythm?

The left arm lead is often used for monitoring cardiac rhythm because it is part of the standard limb leads in an ECG, which assess the heart's electrical activity from different angles. The leads provide essential information about the heart's rhythm and any potential arrhythmias.

The left arm lead, along with its counterpart leads (right arm and left leg), helps create a three-dimensional view of the heart's electrical activity. Specifically, the left arm lead can capture variations in electrical signals that provide insight into the heart's rhythm, including identifying normal sinus rhythm or detecting irregular rhythms.

While other leads, such as the V1 lead, might provide specific information about the anterior wall of the heart or right ventricular function, they are not primarily designated for rhythm monitoring. The right leg lead usually acts as a reference point and does not contribute to rhythm analysis. The right arm lead provides additional data but, like the V1 lead, is not primarily focused on rhythm. Therefore, the left arm lead is the most appropriate choice for ongoing cardiac rhythm monitoring.