NPPB and hydrops fetalis: Elevated BNP and NT-proBNP levels are strongly associated with HF and CVD.2–4,32,33 BNP is predominantly produced in cardiac tissue,1 and the left ventricle is the primary source of circulating BNP in the normal state and under conditions of left ventricular dysfunction.32,33 The BNP gene is activated in cardiomyocytes in response to increased stress of the myocardial wall.