National Cohort Study of Idiopathic and Heritable Pulmonary Arterial Hypertension

What does the study involve? PAH patients will be seen at their local centre by their service team but they will have additional bloods taken. Relatives of PAH patients will be seen every year at their nearest PAH centre. Tests will include: * Epidemiology Questionnaire to assess factors affecting health * An echocardiogram (ECHO) to assess the size, shape, pumping action and the extent of any damage to the heart. * Lung function tests which include blowing measurements to assess gas volumes within the lungs as well as assessment of how the lungs exchange gases. * Optional right heart catheterisation (RHC) to determine how much blood your heart is pumping while you are resting and on exercise. Optional Cardiac Magnetic Resonance tests. To measure heart function. ( to be done only once) * 6 minute walk test. To measure exercise capacity * Cardiopulmonary exercise test. A bicycle exercise test, which will indicate how much blood your heart pumps while resting and with different levels of exercise. * Electrocardiogram (ECG), a test that measures the electrical activity of the heart * Blood tests Controls:Blood sample and medical data collected once