értekezés - Semmelweis Egyetem Doktori Iskola

Summary
Natriuretic peptide levels are good markers of cardiovascular diseases and
ventricular function. NT-proXNP, a new virtual natriuretic peptide analyte, incorporates
information about the levels of both N-terminal pro-atrial and pro-brain natriuretic
peptides (NT-proANP, NT-proBNP). We aimed to investigate the clinical applicability
of NT-proXNP in neonates and infants undergoing open heart surgery. We also aimed
to elucidate the associations of natriuretic peptide levels and postoperative
hemodynamic parameters in this population.
After approval of the institutional review board and parental informed consent,
we enrolled 30 children under the age of 1 year into this prospective study. All patients
underwent elective cardiac operation with cardiopulmonary bypass to achieve complete
biventricular repair. Hemodynamic parameters assessed by transpulmonary
thermodilution and natriuretic peptide levels were recorded preoperatively,
postoperatively and 12, 24, 48 and 72 hours after the arrival at the intensive care unit.
Clinical and laboratory values were analyzed in the first 48 hours following surgery.
The new NT-proXNP immunoassay was sensitive to the activations of both
NT-proANP and NT-proBNP. NT-proXNP and the other natriuretic peptide levels had
strong inverse correlations with cardiac index (CI) and stroke volume index throughout
the postoperative period. There were also correlations between natriuretic peptide levels
and systemic vascular resistance, extravascular lung water and other hemodynamic
parameters, respectively. Conventionally measured parameters such as heart rate, mean
arterial pressure and pulse-pressure product exhibited weaker correlations with CI than
natriuretic peptide levels. Clinical and laboratory values, except for creatinine levels,
showed no correlation with CI. Postoperative NT-proBNP and NT-proXNP levels had
good diagnostic and prognostic performance in ROC analysis for low output syndrome
and mechanical ventilation longer than 72 hours.
NT-proXNP and the natriuretic peptide levels are reliable indicators of the
circulatory state and they are useful for the follow up of neonates and infants after open
heart surgery. Elevated postoperative NT-proBNP and NT-proXNP levels are good
markers of low cardiac output and might be applicable for the prediction of
complications following surgery.
87