As a result, the 12-lead body surface electrocardiogram is, in essence, a left ventricular electrogram with both the main QRS vector (the red arrow) and T vector (the yellow arrow) being directed to the left, inferiorly and posteriorly. Book traversal links for 3.0.2 3.0.1 Introduction Continued Up 3.1.0 Right Bundle Branch Block (RBBB)