ECG
The normal wave of depolarization spreads from the Sinoatrial node (SA node) across the atria (causing the P wave) to the Atrioventricular node (AV node) then down to the Atrioventricular bundle into the Purkinje fibres (causing the QRS complex). This is then followed by a wave of repolarization (causing a T wave) before the next contraction.
