ABSTRACT
The trisomy 16 (Ts16) mouse is generally considered a model for human Down's syndrome (trisomy 21). However, many of the cardiac defects in the Ts16 mouse do not reflect the heart malformations seen in patients suffering from this chromosomal disorder. In this study we describe the conotruncal malformations in mice with trisomy 16. The development of the outflow tract was immunohistochemically studied in serially sectioned hearts from 34 normal and 26 Ts16 mouse embryos ranging from 8.5 to 14.5 embryonic days. Conotruncal malformations observed in the Ts 16 embryos included double outlet right ventricle, persistent truncus arteriosus, Tetralogy of Fallot, and right-sided aortic arch. This spectrum of malformations is remarkably similar to that seen in humans suffering from DiGeorge syndrome (DGS). As perturbation of neural crest development has been proposed in the pathogenesis of DGS we specifically focussed on the fate of neural crest derived cells during outflow tract development of the Ts16 mouse using an antibody that enabled us to trace these cells during development. Severe perturbation of the neural crest-derived cell population was observed in each trisomic specimen. The abnormalities pertained to: 1) the size of the columns of neural crest-derived cells (or prongs); 2) the spatial orientation of these prongs within the mesenchymal tissues of the outflow tract; and 3) the location in which the neural crest cells interact with the myocardium. The latter abnormality appeared to be responsible for ectopic myocardialization found in trisomic embryos. Our observations strongly suggest that abnormal neural crest cell behavior is involved in the pathogenesis of the conotruncal malformations in the Ts16 mouse.
Subject(s)
Heart Defects, Congenital/embryology , Neural Crest/abnormalities , Trisomy , Animals , Connexin 43/analysis , DiGeorge Syndrome/embryology , DiGeorge Syndrome/etiology , DiGeorge Syndrome/pathology , Disease Models, Animal , Down Syndrome/etiology , Down Syndrome/pathology , Female , Fluorescent Antibody Technique, Indirect , Heart Defects, Congenital/etiology , Heart Defects, Congenital/pathology , Heart Ventricles/abnormalities , Karyotyping , Male , Mice , Mice, Inbred C57BL , Mice, Mutant Strains , Neural Crest/chemistry , Neural Crest/pathology , Pregnancy , Yolk Sac/cytologyABSTRACT
We describe the successful reconstruction of a completely obliterated superior vena cava, despite additional obliteration of right internal jugular and subclavian vein, using an end-to-side approach to connect to the innominate and left internal jugular vein. We also document long-term patency.
Subject(s)
Cardiac Catheterization , Extracorporeal Membrane Oxygenation/adverse effects , Superior Vena Cava Syndrome/surgery , Anastomosis, Surgical , Brachiocephalic Veins/surgery , Child, Preschool , Humans , Jugular Veins/pathology , Male , Plastic Surgery Procedures , Subclavian Vein/pathology , Superior Vena Cava Syndrome/etiology , Superior Vena Cava Syndrome/pathology , Vena Cava, Superior/surgerySubject(s)
Fetal Heart/embryology , Heart Defects, Congenital/embryology , Animals , Developmental Biology/methods , Disease Models, Animal , Female , Fetal Heart/metabolism , Heart Defects, Congenital/genetics , Heart Defects, Congenital/metabolism , Histocytological Preparation Techniques , Immunohistochemistry , Male , Mice , Mice, Knockout , Mice, Mutant Strains , PregnancyABSTRACT
In adults, increased QT dispersion has been shown to predict arrhythmic risk as well as risk of sudden death in several clinical settings. It is not known whether or not QT dispersion is increased in children with idiopathic ventricular arrhythmia. We studied three groups of children: (1) 20 patients with idiopathic VT (aged 3-18 years; mean 11.2 years); (2) 30 patients with benign PVCs (aged 1-20 years; mean 10.5 years); and (3) 30 control subjects (aged 4-17 years; mean 12 years). Standard ECGs were reviewed and the dispersion of both QT and JT intervals was compared. No patient had structural heart disease or long QT syndrome. The QT and QTc dispersion (QT delta, QTc delta) among the three groups did not differ: QTc delta of the VT group was 70 ms +/- 30 ms, QTc delta of PVC patients was 60 ms +/- 30 ms, and the QTc delta of the control group was 65 ms +/- 30 ms. The JTc delta among the three groups did not differ as well: JTc delta of the VT group was 70 ms +/- 30 ms, the JTc delta of the PVC group was 60 msec +/- 25 msec, and the JTc delta of the control group was 70 ms +/- 30 ms. We conclude that QT and JT dispersion are not significantly altered in children with idiopathic VT or benign PVCs when compared to control subjects. QT dispersion is not a reliable marker for arrhythmic risk in children with idiopathic ventricular arrhythmias and structurally normal hearts.
