N-terminal pro-B-type natriuretic peptide: a potential marker of fetal heart failure in hemolytic disease.

OBJECTIVES: The hemolysis of red blood cells due to isoimmunisation results in fetal anaemia and hypoxia leading to fetal heart failure. An assessment of N-terminal pro-B-type natriuretic peptide (NT-proBNP) is a routine practice in adult heart failure. No studies on this marker have been reported in fetal heart failure. The aim of the current study was to investigate changes in fetal NT-proBNP serum concentrations before and after intrauterine transfusions and to assess its value as a marker of fetal heart failure.

DESIGN: Therapy of Rh immunisations was performed in 14 fetuses with 61 intrauterine transfusions. Hemoglobin concentration, red blood cells count, hematocrit and NT-proBNP concentrations were assessed in samples taken before and after each transfusion.

RESULTS: An increase in the concentrations of blood parameters was strongly correlated with a decrease in the concentration of NT-proBNP. NT-proBNP concentrations were the greatest with the smallest Hb (4.0-5.9 g/dl), hematocrit and red blood cell (RBC) concentrations, respectively. An increase in Hb concentration by 1mg/dl and the RBC count by 1M/µl resulted in a corresponding decrease in NT-proBNP concentration by 659.0 and 2 007.1 pg/ml, respectively. The NT-proBNP concentrations decreased significantly following 52 transfusions.

CONCLUSIONS: The fetal serum concentration of NT-proBNP appears to be a satisfactory marker for heart failure in fetuses inflicted with severe anaemia caused by hemolytic disease. Intrauterine therapy decreases the severity of anaemia and reduces the fetal heart failure index. There appears to be a strong inverse correlation between the pre-transfusion NT-proBNP concentration and morphological parameters.

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