Effect of Nitric Oxide on Early Myocardial Function in Valvular Surgery

The aim of this study was to evaluate the effect of inhaled nitric oxide on the central (pulmonary) haemodynamics in the patients undergoing surgery for mitral valve or combined defects, with special focus on the period after weaning of the patient from the extracorporeal circulation (ECC). A total of 50 patients were randomly allocated to two groups. One had nitric oxide added to the inhalation mixture at the time of weaning (NO group) and the other was administered nitroglycerine (NTG group). The haemodynamic values were measured on four occasions: before skin incision, after sternotomy, on weaning from ECC and at the end of surgery. A comparison of preand intra-operative values showed that both pulmonary artery pressure and pulmonary vascular resistance were significantly reduced only in the NO group. The increase in cardiac output was higher in the NO group, though it was significant in both groups. The right ventricular systolic function, as measured by ejection fraction, increased in the NO group only. The results show that inhaled nitric oxide, a selective vasodilatator of the pulmonary vascular bed, is more effective in reducing vascular resistance than nitroglycerine and allows for a better function of the right ventricle and easier weaning from ECC after mitral valve repair.