In sildenafil group , arterial partial pressure of oxygen , oxygen saturation and left ventricular ejection fraction , pulmonary systolic pression showed increased trend before and after treatment , which were ( 80 9 ) % to ( 88 9 ) % , ( 84 3 ) to ( 89 7 ) mmHg , 0.70 0.32 to 0.79 0.27 ( P < 0.05 ) , in the mean time , pulmonary systolic pression showed decreased trend from ( 65 18 ) to ( 60 13 ) mmHg ( P < 0.05 ) .