The correlation between serum level of brain natriuretic peptide and amount of left to right shunt

Introduction: Natriuretic peptides such as brain natriuretic peptide (BNP), atrial natriuretic peptide (ANP) and pro-BNP are secreted in response to atrial and/or ventricular stretch. Left to right shunts such as ventricular septal defect (VSD), atrial septal defect (ASD), and patent ductus arteriosus (PDA), are treated medically or surgically. We aimed to evaluate whether the serum level of pro-BNP would be useful to measure the amount of the shunt. Methods: In this cross sectional study, 60 infants and children, in whom physical examinations approved heart murmur, and had undergone echocardiography by which VSD, ASD, or PDA had been proven, were included in the study. The relationship between serum BNP levels and severity of shunt (Qp/Qs) based on echocardiographic and hemodynamic evaluations, was studied. Results: There was a significant relationship between serum level of pro-BNP and the amount of the shunt in the patients with VSD, ASD, and PDA (P=0.01). A positive correlation was seen between pro-BNP serum level and Qp/Qs ratio. The mean ± SE serum level of pro-BNP in patients with Qp/Qs ratio of less than 1.5, equal to 1.5-2, and more than 2 was 30.83±2.4, 217.88±44.6, and 217.13±51.8, respectively showing a significant relationship (P=0.0001). The cut-off point of pro-BNP demonstrating a Qp/Qs ratio more than 1.5 was measured at the level of 40.36 pg/mL, with a sensitivity and specificity of 92% and 79%, respectively. Conclusion: Based on our study, the cut-off point of 40.36 pg/mL or more for pro-BNP, showing a Qp/Qs ratio more than 1.5, can be considered as an indication for interventional procedures.