title: Contrast enhanced micro-computed tomography resolves the 3-dimensional morphology of the cardiac conduction system in mammalian hearts.
abstract: The general anatomy of the cardiac conduction system (CCS) has been known for 100 years, but its complex and irregular three-dimensional (3D) geometry is not so well understood. This is largely because the conducting tissue is not distinct from the surrounding tissue by dissection. The best descriptions of its anatomy come from studies based on serial sectioning of samples taken from the appropriate areas of the heart. Low X-ray attenuation has formerly ruled out micro-computed tomography (micro-CT) as a modality to resolve internal structures of soft tissue, but incorporation of iodine, which has a high molecular weight, into those tissues enhances the differential attenuation of X-rays and allows visualisation of fine detail in embryos and skeletal muscle. Here, with the use of a iodine based contrast agent (I(2)KI), we present contrast enhanced micro-CT images of cardiac tissue from rat and rabbit in which the three major subdivisions of the CCS can be differentiated from the surrounding contractile myocardium and visualised in 3D. Structures identified include the sinoatrial node (SAN) and the atrioventricular conduction axis: the penetrating bundle, His bundle, the bundle branches and the Purkinje network. Although the current findings are consistent with existing anatomical representations, the representations shown here offer superior resolution and are the first 3D representations of the CCS within a single intact mammalian heart.
authors.affiliation: Department of Musculoskeletal Biology, Institute of Ageing & Chronic Disease, University of Liverpool, Liverpool, Merseyside, United Kingdom.
authors.forename: Robert S
authors.initials: RS
authors.lastname: Stephenson
authors.forename: Mark R
authors.initials: MR
authors.lastname: Boyett
authors.forename: George
authors.initials: G
authors.lastname: Hart
authors.forename: Theodora
authors.initials: T
authors.lastname: Nikolaidou
authors.forename: Xue
authors.initials: X
authors.lastname: Cai
authors.forename: Antonio F
authors.initials: AF
authors.lastname: Corno
authors.forename: Nelson
authors.initials: N
authors.lastname: Alphonso
authors.forename: Nathan
authors.initials: N
authors.lastname: Jeffery
authors.forename: Jonathan C
authors.initials: JC
authors.lastname: Jarvis
mesh_terms: D000818:Animals; D001283:Atrioventricular Node / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D002036:Bundle of His / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D003287:Contrast Media / Q000008:administration & dosage; D006321:Heart / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D006329:Heart Conduction System / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D021621:Imaging, Three-Dimensional; D011689:Purkinje Cells / Q000000981:diagnostic imaging; D011817:Rabbits; D051381:Rats; D012849:Sinoatrial Node / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D055114:X-Ray Microtomography
chemical_list: D003287:Contrast Media