Embryonic conduction tissue: a spatial correlation with adult arrhythmogenic areas.
BACKGROUND
The occurrence of arrhythmias in adult patients may arise preferentially in anatomic regions derived from the specialized cardiac conduction system. To examine this hypothesis, we performed a detailed analysis of the developing cardiac conduction system using the recently described CCS-lacZ transgenic mouse strain.


RESULTS
Transgenic embryos (E9.5-15.5) were stained for beta-galactosidase activity and co-stained with the myocardial marker HHF35. Results were reconstructed three dimensionally. CCS-lacZ expression was observed in the sinoatrial node, left and right venous valves, septum spurium, right and left atrioventricular ring, His bundle, bundle branches, and right ventricular moderator band. Furthermore, lacZ-positive cells could be demonstrated for the first time in the left atrium, in the posterior wall surrounding the pulmonary venous orifice. and, in later stages, surrounding the pulmonary venous wall. These cells were continuous with the left venous valve in the right atrium. LacZ-positive tissue also could be identified in Bachmann's bundle, running retro-aortically between the right atrium and left atrium.


CONCLUSIONS
Known arrhythmogenic areas including Bachmann's bundle, the pulmonary veins, and sinus venosus derived internodal structures, demonstrate lacZ expression. These data support the hypothesis that areas derived from the developing cardiac conduction system may contribute to the arrhythmogenic substrate in adult hearts.
Jongbloed
Monique R M
MR
Department of Anatomy & Embryology, Leiden University Medical Center, Leiden, The Netherlands.
Schalij
Martin J
MJ
Poelmann
Robert E
RE
Blom
Nico A
NA
Fekkes
Madelon L
ML
Wang
Zhiyong
Z
Fishman
Glenn I
GI
Gittenberger-De Groot
Adriana C
AC
D000818:Animals; D001145:Arrhythmias, Cardiac / Q000196:embryology* / Q000378:metabolism / Q000503:physiopathology; D002320:Cardiovascular Physiological Phenomena; D004195:Disease Models, Animal; D005314:Embryonic and Fetal Development / Q000502:physiology; D005318:Fetal Heart / Q000196:embryology / Q000254:growth & development / Q000378:metabolism; D005865:Gestational Age; D006325:Heart Atria / Q000196:embryology / Q000254:growth & development / Q000378:metabolism; D006329:Heart Conduction System / Q000196:embryology* / Q000254:growth & development* / Q000378:metabolism; D006352:Heart Ventricles / Q000196:embryology / Q000254:growth & development / Q000378:metabolism; D007763:Lac Operon / Q000502:physiology; D051379:Mice; D008955:Models, Cardiovascular; D009206:Myocardium / Q000378:metabolism; D013223:Statistics as Topic; D001616:beta-Galactosidase / Q000378:metabolism
D001616:beta-Galactosidase