Urinary NT-proBNP levels and echocardiographic parameters for patent ductus arteriosus.

OBJECTIVE: Patent ductus arteriosus (PDA) is common in preterm infants and is associated with significant morbidities. B type natriuretic peptide (BNP) is synthesized in the ventricles secondary to volume overload and excreted as urinary N-terminal pro-brain natriuretic peptide (NT-proBNP). STUDY DESIGN: We report an observational prospective study of 64 preterm infants with birth weight ⩽1000 g. Echocardiographic parameters were obtained from clinical echocardiograms performed in the first week of life. Urinary NT-proBNP/creatinine ratios (pg mg-1) were measured on the same day of the echocardiograms. RESULTS: Infants with medium to large PDA (n=39) had significantly higher NT-proBNP/creatinine levels compared with infants with small PDA (n=10) (median (IQ range): 2333 (792-6166) vs 714 (271-1632) pg mg-1, P=0.01) and compared with infants with no PDA (n=15) (2333 (792-6166) vs 390 (134-1085) pg mg-1, P=0.0003). Urinary NT-proBNP/creatinine ratios were significantly lower post treatment if PDA closed (n=17), P=0.001 or if PDA became smaller after treatment (n=9), P=0.004. Urinary NT-proBNP/creatinine levels correlated with ductal diameter (P⩽0.0001), but not with LA/Ao ratio (P=0.69) or blood flow velocity through the ductus (P=0.06). CONCLUSION: Our findings indicate that there is a positive correlation between ductal diameter and urinary NT-proBNP in preterm infants.

Nesiritide for the treatment of pulmonary hypertension and cor pulmonale in an infant.

Nesiritide is a synthetic form of B-type natriuretic peptide. It is approved for the treatment of acute exacerbations of congestive heart failure in hospitalized adult patients. It is currently under investigation for use in other settings and other patient populations. This article describes administration of nesiritide to an infant patient with severe pulmonary hypertension and cor pulmonale. No adverse reactions occurred during administration of the drug. Specifically, there was no hypertension, vomiting, arrhythmia, or changes in renal function. No changes in renal function occurred in the months subsequent to treatment. This case report illustrates that nesiritide can be safely administered to critically ill infants with pulmonary hypertension and cor pulmonale. Our patient experienced a decrease in pulmonary pressure and improved clinical condition during and after the infusion. However, further study is required to fully evaluate the safety and efficacy of nesiritide for these patients.

1/f alpha noise in spectral fluctuations of quantum systems.

The power law 1/f(alpha) in the power spectrum characterizes the fluctuating observables of many complex natural systems. Considering the energy levels of a quantum system as a discrete time series where the energy plays the role of time, the level fluctuations can be characterized by the power spectrum. Using a family of quantum billiards, we analyze the order-to-chaos transition in terms of this power spectrum. A power law 1/f(alpha) is found at all the transition stages, and it is shown that the exponent alpha is related to the chaotic component of the classical phase space of the quantum system.

Selective coronary angiography in pediatric patients.

Selective coronary angiography (SCA) is an important diagnostic tool in pediatric cardiology; however, there are few reports on its feasibility and safety in young patients. We reviewed our experience with SCA from July 1, 1993 to December 31, 1997. There were 158 cardiac catheterizations that included SCA in patients whose ages ranged from 2 days to 46 years (median, 5.3 years). The most common indication was surveillance for coronary vasculopathy after heart transplantation. A retrograde approach was used in all patients through the femoral artery (n = 157) or umbilical artery (n = 1). Preformed coronary catheters were used and the Judkins left (JL) and Judkins right (JR) were the most common catheters, with the catheter curve size correlating with patient height (R(2) =.76 for JL, R(2) =. 673 for JR). Complications during SCA included brief ST-T wave changes (11%), bradycardia (2.5%), and ventricular fibrillation (0. 6%). Complications of vascular access were transient pulse loss (6%), hematoma (5%), and rebleeding (0.6%). Only one case of femoral artery occlusion was encountered on subsequent cath. In conclusion, complications of SCA were infrequent and serious complications were rare. SCA can be safely performed in pediatric patients at any age including neonates.