Correlation of plasma endothelin-1 levels with pulmonary hypertension after inhaled nitric oxide therapy

ABSTRACT

Variable response to inhaled nitric oxide [iNO] therapy in patients with mitral stenosis [MS] having pulmonary hypertension [PH] has been documented in early studies. The objectives of this study were to measure plasma Endothelin-1 [ET-1] levels in those patients and to correlate them with pulmonary vascular indices after iNO therapy. It was Quesi-experimental study. Thirty patients with mitral or mixed mitral and aortic valve disease with severe pulmonary hypertension and vascular indices and cardiac output were recorded. After the surgery, 10-20 ppm iNO was administered for 1 hour and all the parameters were again recorded. Patients were grouped into responders and non responders on the basis of% reduction in Pulmonary Vascular Resistance [PVR] after iNO therapy. Plasma ET-1 levels were measured in both groups by ELISA before and after the iNO therapy. Paired sample t-test was used to compare mean values for significance. The correlations between variables were then calculated by using Pearson's coefficient. The plasma ET-1 levels were very high in all patients. They reduce in responders after iNO therapy; non-responders paradoxically showed significant increase in the levels of ET-1 after iNO therapy. Moreover, a positive correlation was observed in plasma ET-1 levels and post operative levels of PVR. The correlation of changes in PVR and plasma ET-1 is a key mediator of poor response in PH secondary to MS, after iNO therapy