The purpose of this study is to determine whether the study drug is effective in the long-term treatment of primary or secondary pulmonary hypertension

The study has previously been posted by Schering AG, Germany. Schering AG, Germany has been renamed to Bayer Schering Pharma AG, Germany.

Bayer Schering Pharma AG, Germany is the sponsor of the trial.

Inclusion Criteria:

• Male or female patients
• Secondary pulmonary hypertension
• Mean pulmonary artery pressure equal or above 40 mmHg or primary pulmonary hypertension with a pressure equal or above 30 mmHg while resting during appropriate conventional treatment
• Written informed consent after having been duly informed about all diagnostic and therapeutic measures involved in the study

Exclusion Criteria:

• Clinical Instability at baseline
• Pulmonary venous obstruction
• Global respiratory insufficiency
• Obstructive ventilation disorders, Interstitial pulmonary disease
• Cerebrovascular events
• Myocardial infarction or major cardiac surgery within 3 months prior to baseline
• Bleeding disorders or bleeding risk
• Severe hepatic insufficiency or renal insufficiency
• Malignant diseases
• HIV positive
• Pregnancy, female patients of child-bearing potential without adequate contraception and nursing mothers
• Congenital or acquired valvular defects and myocardial function disorders not related to pulmonary hypertension
• Prior pulmonary embolism
• Collagenosis
• Pulmonary arterial or valvular stenosis