Overview:

The conduction typically starts at the SA node and spreads outwards through the atria and downwards towards the AV node and then down through the nonconductive membrane (AV junction) to the ventricles. A short pause in conduction at the AV node (PR segment on an EC) allows filling of the ventricles before contraction (systole) of the ventricles. In the image and video clip we can see the pacemakers, bundle branches and fibres accosiated with the cardiac conduction pathway.