TY - JOUR
T1 - Development of the cardiac conduction system in atrioventricular septal defect in human trisomy 21
AU - Blom, Nico A.
AU - Ottenkamp, Jaap
AU - Deruiter, Marco C.
AU - Wenink, Arnold C. G.
AU - Gittenberger-de Groot, Adriana C.
PY - 2005
Y1 - 2005
N2 - In patients with atrioventricular septal defect (AVSD), the occurrence of nonsurgical AV block has been reported. We have looked for an explanation in the development of the AV conduction system. Human embryos with AVSD and trisomy 21 and normal embryos were examined (age 5-16 wk gestation). Antibodies to human natural killer cell-1 (HNK-1), muscle actin (HHF-35), and collagen VI were used to delineate the conduction system. As in normal hearts, HNK-1 transiently stains the AV conduction system, the sinoatrial node, and parts of the sinus venosus in AVSD. A large distance is present between the superior and inferior node-like part of the right AV ring bundle, comparable to 6-wk-old normal hearts. The definitive inferior AV node remains in dorsal position from 7 wk onward and does not appose to the superior node-like part as seen in normal hearts. Furthermore, in AVSD, a transient third HNK-1-positive "middle bundle" branch that is continuous with the retroaortic root branch and the superior node-like part can be identified, and thus the AV conduction system forms a figure-of-eight loop. At later stages, the AV node remains in dorsal position close to the coronary sinus ostium with a long nonbranching bundle that runs through thin fibrous tissue toward the ventricular septum. The formation of the AV node and the ventricular conduction system in AVSD and Down syndrome differs from normal development, which can be a causative factor in the development of AV conduction disturbances
AB - In patients with atrioventricular septal defect (AVSD), the occurrence of nonsurgical AV block has been reported. We have looked for an explanation in the development of the AV conduction system. Human embryos with AVSD and trisomy 21 and normal embryos were examined (age 5-16 wk gestation). Antibodies to human natural killer cell-1 (HNK-1), muscle actin (HHF-35), and collagen VI were used to delineate the conduction system. As in normal hearts, HNK-1 transiently stains the AV conduction system, the sinoatrial node, and parts of the sinus venosus in AVSD. A large distance is present between the superior and inferior node-like part of the right AV ring bundle, comparable to 6-wk-old normal hearts. The definitive inferior AV node remains in dorsal position from 7 wk onward and does not appose to the superior node-like part as seen in normal hearts. Furthermore, in AVSD, a transient third HNK-1-positive "middle bundle" branch that is continuous with the retroaortic root branch and the superior node-like part can be identified, and thus the AV conduction system forms a figure-of-eight loop. At later stages, the AV node remains in dorsal position close to the coronary sinus ostium with a long nonbranching bundle that runs through thin fibrous tissue toward the ventricular septum. The formation of the AV node and the ventricular conduction system in AVSD and Down syndrome differs from normal development, which can be a causative factor in the development of AV conduction disturbances
U2 - https://doi.org/10.1203/01.PDR.0000179388.10921.44
DO - https://doi.org/10.1203/01.PDR.0000179388.10921.44
M3 - Article
C2 - 16148066
SN - 0031-3998
VL - 58
SP - 516
EP - 520
JO - Pediatric Research
JF - Pediatric Research
IS - 3
ER -