New aspects of development of the cardiac conduction system, clinical relevance

Electrophysiological and new immunohistochemical markers have resulted in a better understanding of the development of the cardiac conduction system. In the primary heart tube the blood is pumped forward by peristaltic contractions as a result of alternating slow and fast conducting segments. At later stages a more specialized conduction system develops. The contribution of the primary fold and the sinus venosus to the formation of the cardiac conduction system is discussed as well as the role of extracardiac cells such as neural crest and epicardial derived cells. These new developmental aspects of the cardiac conduction system could provide an explanation of the position conduction system in heart malformations and certain arrhythmias in patients with structurally normal hearts.