The main objective is to validate the safety and efficacy of intravenous and oral sildenafil in the acute vasodilator test in patients with persistence of, at least, moderate pulmonary hypertension after valvular surgery successfully, with a correct left ventricular function and no valvular disease hemodynamically significant.

Inclusion Criteria:

• Patients clinically stable, at least 1 year after the completion of successful valve surgery, with persistent pulmonary artery systolic pressure> 50 mmHg,
• normal left ventricular function and no significant valvular disease in 2 separate Doppler ultrasound studies at least 1 month.

Exclusion Criteria:

• Patients with other cardiac and noncardiac diseases will be excluded.