In most cases, the cause is unknown, but it may be related to a viral infection. It may occur as a complication of certain connective tissue diseases, such as lupus or CREST, or as a complication of certain blood cancers (leukemia or lymphoma) or chemotherapy.

The disorder is most common amongst children and young adults. Progression of the disease leads to narrowed pulmonary veins, pulmonary hypertension, congestion, and edema (swelling) of the lungs.

• Shortness of breath
• Fatigue on exertion
• Fainting
• Coughing up blood

Signs of high blood pressure in the veins of the lungs are seen with physical examination. Splitting of heart sounds may be present when the chest is examined with a stethoscope (auscultation). The jugular venous pressure may be elevated. There may be nail abnormalities (finger clubbing, an enlargement of the bases of the fingernails) and a bluish coloration of the skin due to lack of oxygen (cyanosis).

Tests can include:

• Arterial blood gases
• Chest X-ray
• Chest CT
• Cardiac catheterization
• Pulmonary angiogram
• Echocardiogram
• Lung biopsy

Currently, there are no known effective medical treatments. Vasodilator drugs (drugs that dilate the blood vessels) that are used in other forms of pulmonary hypertension may be harmful in pulmonary veno-occlusive disease. Lung transplantation is the only treatment that has proven to be effective.

The outcome is often very poor in infants with a survival rate of just a few weeks. Survival may be months to a few years in adults.

• Progressive difficulty breathing
• Pulmonary hypertension
• Right sided heart failure (cor pulmonale)
• Coughing up blood

Call your health care provider if symptoms of this disorder develop. Fainting, shortness of breath, and episodes of no breathing are emergency/urgent symptoms.