Axis Deviation occurs when a patient has a shift in the primary direction of the flow of the electricity within the heart. The term vector is used to describe an imaginary arrow that points from the start of the first impulse to the termination of that impulse. Normal conduction begins with the SA Node (top of the right atrium) and terminates with the Purkinje fibers leading to the bundle branches (T Wave/Ventricular Repolarization).