title: Structure, function and clinical relevance of the cardiac conduction system, including the atrioventricular ring and outflow tract tissues.
abstract: It is now over 100years since the discovery of the cardiac conduction system, consisting of three main parts, the sinus node, the atrioventricular node and the His-Purkinje system. The system is vital for the initiation and coordination of the heartbeat. Over the last decade, immense strides have been made in our understanding of the cardiac conduction system and these recent developments are reviewed here. It has been shown that the system has a unique embryological origin, distinct from that of the working myocardium, and is more extensive than originally thought with additional structures: atrioventricular rings, a third node (so called retroaortic node) and pulmonary and aortic sleeves. It has been shown that the expression of ion channels, intracellular Ca(2+)-handling proteins and gap junction channels in the system is specialised (different from that in the ordinary working myocardium), but appropriate to explain the functioning of the system, although there is continued debate concerning the ionic basis of pacemaking. We are beginning to understand the mechanisms (fibrosis and remodelling of ion channels and related proteins) responsible for dysfunction of the system (bradycardia, heart block and bundle branch block) associated with atrial fibrillation and heart failure and even athletic training. Equally, we are beginning to appreciate how naturally occurring mutations in ion channels cause congenital cardiac conduction system dysfunction. Finally, current therapies, the status of a new therapeutic strategy (use of a specific heart rate lowering drug) and a potential new therapeutic strategy (biopacemaking) are reviewed.
authors.affiliation: University of Manchester, UK. halina.dobrzynski@manchester.ac.uk
authors.forename: Halina
authors.initials: H
authors.lastname: Dobrzynski
authors.forename: Robert H
authors.initials: RH
authors.lastname: Anderson
authors.forename: Andrew
authors.initials: A
authors.lastname: Atkinson
authors.forename: Zoltan
authors.initials: Z
authors.lastname: Borbas
authors.forename: Alicia
authors.initials: A
authors.lastname: D'Souza
authors.forename: John F
authors.initials: JF
authors.lastname: Fraser
authors.forename: Shin
authors.initials: S
authors.lastname: Inada
authors.forename: Sunil J R J
authors.initials: SJ
authors.lastname: Logantha
authors.forename: Oliver
authors.initials: O
authors.lastname: Monfredi
authors.forename: Gwilym M
authors.initials: GM
authors.lastname: Morris
authors.forename: Anton F M
authors.initials: AF
authors.lastname: Moorman
authors.forename: Thodora
authors.initials: T
authors.lastname: Nikolaidou
authors.forename: Heiko
authors.initials: H
authors.lastname: Schneider
authors.forename: Viktoria
authors.initials: V
authors.lastname: Szuts
authors.forename: Ian P
authors.initials: IP
authors.lastname: Temple
authors.forename: Joseph
authors.initials: J
authors.lastname: Yanni
authors.forename: Mark R
authors.initials: MR
authors.lastname: Boyett
mesh_terms: D000818:Animals; D047108:Embryonic Development; D006329:Heart Conduction System / Q000033:anatomy & histology / Q000196:embryology / Q000502:physiology*; D006801:Humans; D007473:Ion Channels / Q000235:genetics; D009154:Mutation
chemical_list: D007473:Ion Channels