A person with pulmonary hypertension has abnormally high blood pressure in the arteries that deliver blood from the heart to the lungs.

There are two main forms:

• Primary pulmonary hypertension:
• There is no clear cause for the high blood pressure
• Secondary pulmonary hypertension:
• The high blood pressure is caused by underlying heart or lung disease

Pulmonary hypertension places abnormal stress on the heart, which can lead to heart failure.