Number of candidates for this study is expected to be too small.

The purpose of this study is to determine whether Sildenafil is effective in the treatment of sustained pulmonary artery hypertension after corrected mitral valve disease.

Inclusion Criteria:

• New York Heart Association Functional class (NYHA Fc) ≥ 2 dyspnea which was sustained till one year after the previous mitral valve surgery (repair or replacement)
• TR Vmax ≥ 3.5m/s by echocardiography
• Normal left ventricle ejection fraction (EF ≥ 50%)
• Pulmonary vascular resistance ≥ 3 Wood Unit or diastolic pressure gradient ≥ 7mmHg by cardiac catheterization

Exclusion Criteria:

• Other valve disease more than moderate degree (ex. aortic stenosis, aortic regurgitation)
• Liver cirrhosis
• Chronic renal failure with serum creatinine ≥ 1.7mg/dL
• Lung disease (ex. chronic obstructive pulmonary disease, Asthma)
• Thyroid dysfunction
• Other causes which can lead to pulmonary hypertension