Document Detail

Accessory atrioventricular myocardial connections in the developing human heart: relevance for perinatal supraventricular tachycardias.
MedLine Citation:
PMID:  18506001     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: Fetal and neonatal atrioventricular (AV) reentrant tachycardias can be life-threatening but resolve in most cases during the first year of life. The transient presence of accessory AV myocardial connections during annulus fibrosus development may explain this phenomenon. METHODS AND RESULTS: A total of 45 human embryonic, fetal, and neonatal sectioned hearts (4 to 36 weeks of development) were studied immunohistochemically. Accessory myocardial AV connections were quantified and categorized according to their specific location, and 3D reconstructions were made. Between 4 and 6 weeks of development, the atrial and ventricular myocardium was continuous at the primitive AV canal. At 6 to 10 weeks, numerous accessory myocardial AV connections were identified in the left (45%), right (35%), and septal (20%) regions of the AV junction. Most right-sided accessory connections comprised distinct myocardial strands, whereas left-sided connections consisted of larger myocardial continuities. At 10 to 20 weeks, all accessory AV connections comprised discrete myocardial strands and gradually decreased in number. The majority of accessory connections were located in the right AV junction (67%), predominantly in the lateral aspect (45%). Seventeen percent of the accessory connections were observed in the left AV junction, and 16% were observed in the septal region. 3D reconstructions of the developing AV nodal area at these stages demonstrated multiple AV node-related accessory connections. From 20 weeks until birth, and in neonatal hearts, no further accessory myocardial AV connections were observed. CONCLUSIONS: Isolation of the AV junction is a gradual and ongoing process, and right lateral accessory myocardial AV connections in particular are commonly found at later stages of normal human cardiac development. These transitory accessory connections may act as substrate for AV reentrant tachycardias in fetuses or neonates.
Nathan D Hahurij; Adriana C Gittenberger-De Groot; Denise P Kolditz; Regina Bökenkamp; Martin J Schalij; Robert E Poelmann; Nico A Blom
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2008-05-27
Journal Detail:
Title:  Circulation     Volume:  117     ISSN:  1524-4539     ISO Abbreviation:  Circulation     Publication Date:  2008 Jun 
Date Detail:
Created Date:  2008-06-03     Completed Date:  2008-07-23     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0147763     Medline TA:  Circulation     Country:  United States    
Other Details:
Languages:  eng     Pagination:  2850-8     Citation Subset:  AIM; IM    
Department of Pediatric Cardiology, Leiden University Medical Center, Leiden, Netherlands.
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MeSH Terms
Atrioventricular Node / growth & development*
Embryo, Mammalian
Heart / anatomy & histology,  growth & development*
Imaging, Three-Dimensional
Infant, Newborn
Tachycardia, Supraventricular / etiology*

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