Study of relationship between brain natriuretic peptide levels and heart function after open-heart surgery in children with congenital heart disease

Abstract

To investigate significance of plasma brain natriuretic peptide (BNP) on evaluation of cardiac function in children with congenital heart disease (CHD). One hundred and fifty-three children with CHD were enrolled.Plasma level of BNP was measured by enzyme linked immunosorbent assay (ELISA) at 24 hours after cardiac operation.The left ventricular ejection fraction (LVEF) was examined by echocardiogram at the same time. Cardiac index (CI) was measured with thoracic impedance method (CI1) and pulse indicator continuous cardiac output (PiCCO) system (CI2) at the same time. Correlation between BNP, LVEF, CI1 and CI2 was analyzed. The length of mechanical ventilation, the length of intensive care unit (ICU) stay, the length of hospital stay, and mortality were compared between BNP<140 ng/L group (group A, n = 108) and BNP>140 ng/L group (group B, n = 45). The average plasma BNP level of 153 children with CHD was (168.8 ± 71.6) ng/L. The average LVEF was 0.409 ± 0.137, CI1 was (51.7 ± 15.0) ml·s(-1)·m(-2), and CI2 was (61.7 ± 11.7) ml·s(-1)·m(-2). Plasma BNP showed negative correlation with CI1 and CI2 [r(1) = -0.79, r(2) = -0.79, both P < 0.01]. LVEF showed positive correlation with CI1 and CI2 [r(1) = 0.68, r(2) = 0.68, both P < 0.01].CI1 showed positive correlation with CI2 (r = 0.88, P < 0.01). The length of mechanical ventilation (hours), the length of ICU stay (days), and the length of hospital stay (days) in group B were significantly longer than those in group A (the length of mechanical ventilation: 39.7 ± 11.6 vs. 26.4 ± 13.5, the length of ICU stay: 4.9 ± 1.3 vs. 2.5 ± 0.9, the length of hospital stay: 15.9 ± 5.1 vs. 11.2 ± 3.7, all P < 0.01). Mortality of two groups showed no statistical difference. Plasma BNP was useful for post operative evaluation of cardiac function among the children with CHD, and also to predicting the outcome of the patients.