S5 lead for enhancing atrial activity

S5 lead for enhancing atrial activity

S5 lead is meant for enhancing atrial activity on the ECG and can be taken in the following configuration:
Right arm electrode is kept on the manubrium sternum, left arm electrode on the fifth right intercostal space at the right sternal border and the right leg electrode on the right leg as the reference electrode. Right arm lead will be negative and left arm lead will be positive. Enhancing atrial activity is useful to detect otherwise invisible P waves in wide QRS tachycardia to differentiate between ventricular and supraventricular tachycardia. In supraventricular tachycardia, it may help in identifying retrograde P waves.