Pacemaker cells and Purkinje fibres in the conduction system are specialized cardiomyocytes that generate and conduct electrical impulses. The sinoatrial node (SAN), which is composed of a group of pacemaker cells, resides in the right atrium generating impulses to initiate heart contraction. The atrioventricular node (AVN) is located between the atria and ventricles, and it conducts an electrical impulse from the atria to the ventricles. Mei Xin,