Correlation of plasma B-type natriuretic peptide with shunt volume in children with congenital heart disease involving left-to-right shunt.

Introduction: Concentrations of B-type natriuretic peptide (BNP) are recognised as a reliable marker of ventricular dysfunction in adults. In this study, plasma levels of BNP were determined in children with congenital heart disease (CHD) involving a left-to-right shunt, and were correlated with the shunt volume.
Methods: Seventy-six children (38 boys/38 girls, mean age 22.4 months) with CHD (Group A: 31 with atrial septal defect [ASD], 23 with ventricular septal defect [VSD], 8 with ASD and VSD, 14 with patent ductus arteriosus [PDA]) and 34 healthy children (group B) were studied. BNP was measured by chemiluminescent microparticle immunoassay in all children. The amount of shunt (the ratio of pulmonary blood flow/systemic blood flow: Qp/Qs) was measured using Doppler velocimetry and two-dimensional echocardiography. A haemodynamically significant left-to-right shunt was defined as Qp/Qs>1.5. Correlations were evaluated between all patient groups and healthy subjects and BNP was compared with echocardiographic data reflecting right and left ventricle volume overload.
Results: Thirty-four children of group A had Qp/Qs>1.5 (group A1) and 42 Qp/Qs<1.5 (group A2). BNP levels were higher in group A1 than group A2 (p=0.015), while there were no significant differences in BNP between group A2 and group B (p=0.79). BNP 24.4 pg/ml was determined as the cut-off point to identify patients with Qp/Qs>1.5. BNP values were similar among patients with ASD and VSD, but they were significantly higher in patients with PDA. BNP was positively correlated with Qp/Qs (r=0.59, p<0.001), and with the pulmonary artery velocity (r=0.27) and gradient (r=0.49), while there was a negative correlation with ejection fraction (r=-0.14). BNP levels were significantly higher in 10 infants with clinical signs of heart failure (p=0.025).
Conclusion: These results, which are consistent with previous reports, suggest a possible role of BNP as an early diagnostic marker of the significance of shunt in children with CHD.