frontal qrs loop

vectorcardiogram electrocardiogram vector qrs loop cardiac vector frontal lead system transverse frontal transverse counterclockwise clockwise 8-shaped operation ventricular excitatory depolarization monitoring interventricular septum conduction left bundle branch right ventricle ecg segment electrocardiograph healthy beat cardiac cardiology diagnosis disease ecg education ekg theory health heart heartbeat medical medicine wave rhythm chest leads heart rate electrical activity impulse excitation human ventricle