The aim was to evaluate the efficiency of therapy with sildenafil on morphological and functional state of right ventricle (RV), pulmonary artery systolic pressure (PASP) and status of red blood cells NO-system in patients with idiopathic pulmonary hypertension (IPAH). The study included 31 patients with IPAH and 10 healthy persons. We evaluated PASP, RV anteroposterior and transversal sizes, RV shortening fraction, RV free wall
thickness according to the echo- and Doppler echocardiography, measured the activity of constitutive and inducible NO-synthase, contents of nitrite anion and nitrate anion in blood erythrocytes by spectrophotometric
method before and after 24 weeks of treatment sildenafil 50 mg daily. Long-term treatment of IPAH including sildenafil decreased PASP by 19%, RV diameter by 12% and RV shortening fraction by 56%.