The animation below is of a normal sinus
rhythm. It shows conduction in the
heart beginning at the initiation of impulses (red dots) at the SA node.
The impulses are propagating through the SA node, to the AV node,
through the bundle of His and bundle branches and finally to the
ventricles. Note the relation of the heart's electrical activity and
contraction (pumping), and the EKG below. Note that the animation had
been slowed about 10 times normal heart rate to show the details.