Background. Brain natriuretic peptide is a relatively recently discovered circulating mediator that has been correlated with the degree of heart failure in adults. This study evaluated the preoperative and postoperative brain natriuretic peptide levels in infants and children undergoing ventricular septal defect repair. Methods. The study enrolled 18 infants and children (ages 2 months to 15.6 years) scheduled for surgical repair of their ventricular septal defects. Brain natriuretic peptide levels were drawn preoperatively and then postoperatively at 1, 24, 48, and 72 hours. The amount of shunt ( the ratio of pulmonary blood flow [Q(p)]/systemic blood flow [Q(s)]) through the ventricular septal defect was determined by saturation levels performed in the catheterization laboratory or intraoperatively. Results. The preoperative brain natriuretic peptide levels (pg/ mL) averaged 78 +/- 57, and the postoperative levels were 168 +/- 241 at 1 hour, 418 +/- 330 at 24 hours, 405 +/- 364 at 48 hours, and 391 +/- 397 at 72 hours. These differences were significant for each postoperative time point compared with preoperative values. Preoperative brain natriuretic peptide and the Q(p)/Qs were significantly correlated (age-adjusted R-2 = 0.33, p < 0.001). Conclusions. Brain natriuretic peptide levels have a close correlation with the physiologic volume load caused by ventricular septal defects. The preoperative brain natriuretic peptide levels were also found to be predictive for the postoperative time course of brain natriuretic peptide level changes. These results suggest that brain natriuretic peptide levels may be a useful clinical marker in infants and children with ventricular septal defects.

The differential developmental effects of hypoxia on antegrade fast and slow and retrograde conduction through the atrioventricular junction are unknown. This study describes the effects of hypoxia on fast and slow antegrade atrioventricular node, infra-Hisian and retrograde conduction in immature and mature hearts during premature pacing protocols in excise, perfused adult and neonatal rabbits. The results are: (1) antegrade conduction delay through the atrioventricular node is the same developmentally, but delay through the His-Purkinje system is greater in adults; (2) hypoxia reduces the extra delay in the His-Purkinje system in adults; (3) fast atrioventricular node conduction is more sensitive to hypoxia in neonates than in adults, and slow atrioventricular node conduction is more sensitive to hypoxia in adults than in neonates, and (4) retrograde atrioventricular node conduction is more resistant to hypoxia in neonates than in adults.

Radiofrequency energy applications with a standard 5Fr 3 mm tip electrode catheter facilitated opening of the pulmonary valve in neonates with pulmonary atresia. Shortening of the catheter tip electrode would probably improve efficiency.

This study investigates developmental differences in ventriculoatrial conduction during incremental ventricular pacing in the perfused rabbit heart. In 16 adult and 13 neonatal perfused preparations, ventricular prematures S2 were introduced after a train of 10 S1 stimuli. S2 was progressively shortened until the ventricular refractory period was reached. Parameters of retrograde conduction and refractoriness were then compared.

This report suggests that in the absence of aortic regurgitation, Doppler peak and mean gradients are useful predictors of catheter peak-to-peak aortic stenosis gradients >50 mm Hg; however, in the presence of aortic regurgitation, the predictive value diminishes dramatically, but improves when electrographic data are incorporated. We present potentially useful equations to help predict the need for interventional catheterization for valvar aortic stenosis.