Cardiac conduction system

The atria and the ventricles of the heart contract rhythmically and sequentially to achieve efficient blood flow. This contraction pattern is orchestrated by the cardiac conduction system, comprising specialized cardiomyocytes that initiate and propagate the cardiac electrical impulse. Genetic defects cause dysfunction of the cardiac conduction system leading to arrhythmias, emphasizing the need to understand the molecular and cellular mechanisms involved in its development and function. In the adult heart, the electrical impulse is generated in the sinoatrial node and traverses slowly through the atrioventricular node and rapidly through the atrioventricular bundle, the left and right bundle branches, and the peripheral ventricular conduction system. All components have a unique function, shape, and molecular composition but share particular properties acquired during embryogenesis. During embryonic development, the components are gradually formed from embryonic cardiomyocytes involving conserved molecular regulatory networks. In this chapter, the developmental origin, known signaling pathways, transcription factors, ion channels, and gap junctions involved in the development and functioning of the cardiac conduction system will be addressed.