OBJECTIVESTo assess the changes of the levels of plasma endothelin (ET-1), nitric oxide (NO) and atrial natriuretic peptide (ANP) after cardiopulmonary bypass (CPB) and the influence of inhaled nitric oxide in patients with ventricular septal defect (VSD) and pulmonary hypertension (PH).

METHODSSixty patients with VSD were enrolled in this study. They were divided into 2 groups: group A [no-PH group, mean pulmonary artery pressure (mPAP) < 20 mm Hg (1 mm Hg = 0.133 kPa) n = 20] and group B (PH group, mPAP > 20 mm Hg, n = 40). Group B was subdivided into two groups by randomized block, group B(1) (inhaled NO group, n = 20) and group B(2) (contrast group, n = 20). The plasma ET-1, NO, ANP concentrations were assayed at 24 h pre-operation and 0 h, 1 h, 5 h, 12 h, 24 h, 48 h after CPB.

RESULTSThe preoperative plasma ET-1, NO and ANP concentrations in group B were significantly higher than those in group A. In three groups, the plasma ET-1 concentration at 0 h after CPB was significantly higher than that at 24 h pre-operation, and the plasma NO concentration at 0 h after CPB was significantly lower than that at 24 h pre-operation. In group B, the plasma ANP concentration at 0 h after CPB was significantly higher than that at 24 h pre-operation. After CPB, the plasma ET-1 concentration in group B(1) decreased faster than that in group B(2), and the plasma NO concentration in group B(1) increased faster than that in group B(2). In group B, the preoperative plasma ET-1 concentration negatively correlated with the preoperative plasma NO concentration and positively correlated with the preoperative ANP concentration.

CONCLUSIONSThe broken dynamic balance of ET-1/NO may take part in generation and development of pulmonary hypertension. ANP acts as a favorable physiological regulating factor in the pathogenesis of pulmonary hypertension. CPB can regulate the level of ET-1 up and NO and ANP down while inhaled NO can cause the level of ET-1 down and the level of NO up.