<prompt> Pulmonary hypeension is caused byInterstitial lung diseaseMyocardial infarctionSystemic hypeensionThromboembolism  <response>: Category 1. Pulmonary aerial hypeension PAH Key feature: elevation in pulmonary aerial pressure PAP with normal pulmonary capillary wedge pressure pcwp Includes: Idiopathic IPAH Sporadic Familial Exposure to drugs or toxins Persistent pulmonary hypeension of the newborn Pulmonary capillary hemangiomatosis PCH Associated with other active conditions Collagen vascular disease Congenital systemic-to-pulmonary shunts Poal hypeension HIV infection Category 2. Pulmonary venous hypeension Key feature: elevation in PAP with elevation in pcwp Includes: Left-sided atrial or ventricular hea disease Left-sided valvular hea disease Pulmonary venous obstruction Pulmonary venoocclusive disease PVOD Category 3. Pulmonary hypeension associated with hypoxemic lung disease Key feature: chronic hypoxia with mild elevation of PAP Includes: Chronic obstructive lung disease Interstitial lung disease Sleep-disordered breathing Alveolar hypoventilation disorders Chronic exposure to high altitude Developmental abnormalities Category 4. Pulmonary hypeension due to chronic thromboembolic disease Key feature: elevation of PA pressure with documentation of pulmonary aerial obstruction for 3 monthsIncludes: Chronic pulmonary thromboembolism Nonthrombotic pulmonary embolism tumor, foreign material Category 5. Miscellaneous Key feature: elevation in PAP in association with a systemic diseasewhere a causal relationship is not clearly understood. Includes: Sarcoidosis Chronic anemias Histiocytosis X Lymphangiomatosis Schistosomiasis ref:Harrison;s principles of internal medicine,ed 18,pg no 2078 