Impact of cardiac surgery on plasma levels of B-type natriuretic peptide in children with congenital heart disease

OBJECTIVE: To examine prospectively the effect of cardiac surgery on plasma concentration of B-type natriuretic peptide (BNP) in children with congenital heart disease.

SETTING: Tertiary referral center.

METHODS: BNP plasma concentration was measured by sandwich immunoassay (Biosite) in 65 consecutive patients with congenital heart disease (age 4 days to 17.1 years, mean (S.D.) age 3.6 (4.7) years, median age 1.0 years) on the day before and after surgical therapy. BNP levels were compared to perioperative data and to healthy subjects.

RESULTS: BNP increased significantly (p<0.001) after cardiac surgery from median 31 pg/ml (mean 189 pg/ml) to median 453 pg/ml (mean 607 pg/ml) and remained significantly elevated during the first week (p<0.001). After a first peak mean (S.D.) 1.3 (0.7) days after surgery, there was a significant decrease of plasma BNP followed by a second peak 5.1 (1.1) days after surgery. Postoperative BNP plasma concentration was correlated to BNP before surgery (r=0.58, p<0.001), to cardiopulmonary bypass duration (r=0.52, p<0.001) and to serum lactate concentration at the first day after surgery (r=0.49, p<0.001).

CONCLUSIONS: In children with congenital heart defects plasma BNP increased immediately after cardiac surgery despite haemodynamic unloading. The correlation to cardiopulmonary bypass time and serum lactate concentration and the similarity between the pattern of BNP release after surgery and after myocardial ischaemia might be explained by a cytoprotective role for BNP after cardiac surgery.