Figure 1. Left bundle area pacing by the transseptal technique, the green arrows the direction of electrical activation. A Left bundle lead at the right ventricular septum showing right ventricular septal capture. The ECG shows notched QRS in V1 and RWPT measures 110ms.B Left bundle lead in the mid-septum. The notch in lead V1 has progressed and RWPT has reduced to 100ms. C left bundle capture right bundle branch block in lead V1 with a terminal R wave (R prime) and RWPT 66ms.