Paradoxical Relationship Between B-type Natriuretic Peptide and Pulmonary Vascular Resistance in Patients with Ventricular Septal Defect and Concomitant Severe Pulmonary Hypertension

B-type natriuretic peptide (BNP) reflects volume overload on left ventricle and pulmonary hypertension (PH) in patients with ventricular septal defect (VSD). Pulmonary vascular resistance (PVR) has been reported to correlate positively with BNP in VSD patients with various degrees of PH. We aimed to investigate the relationship between PVR and BNP in VSD patients with severe PH. We examined 24 subjects with VSD concomitant severe PH aged from 2 months to 17 years (median: 4 months). The ratio of pulmonary to systemic pressure (Pp/Ps), the ratio of pulmonary to systemic flow (Qp/Qs), the ratio of pulmonary to systemic resistance (Rp/Rs), and PVR were determined by cardiac catheterization. PVR and Rp/Rs ranged from 1.6 to 15.5 (mean: 5.7 ± 3.9) Wood unit · m² and 0.1 to 0.8 (mean: 0.4 ± 0.2), respectively. BNP ranged from 5.5 to 69 (mean: 31 ± 19) pg/ml. Negative correlations were observed between BNP and PVR (r = -0.56, p = 0.004) and BNP and Rp/Rs (r = -0.51, p = 0.01). BNP was significantly lower (<10 pg/ml) in VSD patients with Eisenmenger physiology as compared with the others (p = 0.003). We should draw attention to evaluate BNP values in VSD patients with severe PH.