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 ( @ @ ) % to ( @ @ ) % , ( @ @ ) to ( @ @ ) mmHg , @ @ to @ @ ( P < @ ) , in the mean time , pulmonary systolic pression showed decreased trend from ( @ @ ) to ( @ @ ) mmHg ( P < @ ) .