Embryonic Conduction Tissue:

A Spatial Correlation with Adult Arrhythmogenic Areas


  • This work was supported by Grant HL64757 from the National Institutes of Health to Dr. Fishman and a Burroughs Wellcome Fund Clinical Scientist Award in Translational Research to Dr. Fishman.

  • Manuscript received 4 September 2003; Accepted for publication 24 October 2003.

Address for correspondence: Adriana C. Gittenberger-de Groot, Ph.D., Department of Anatomy & Embryology, Leiden University Medical Center, P.O. Box 9602, 2300 RC Leiden, The Netherlands. Fax: 31-71-5276680; E-mail: acgitten@lumc.nl


Introduction: 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.

Methods and Results: Transgenic embryos (E9.5–15.5) were stained for β-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.

Conclusion: 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. (J Cardiovasc Electrophysiol, Vol. 15, pp. 349-355, March 2004)