<International Circulation>: Other than primary pulmonary hypertension， many other conditions can cause pulmonary hypertension. Could you outline the common diseases that lead to pulmonary hypertension and the pathophysiological mechanism?

    Prof Wilkins: As you say， pulmonary hypertension presents in different forms and different background conditions and I think we tend to be rather focused on idiopathic pulmonary arterial hypertension and chronic thromboembolic disease in the West. If you consider the presentations worldwide， then undoubtedly the commonest cause of pulmonary arterial hypertension is schistosomiasis. It is a global disease and despite the fact we have effective treatments for the infection， the complication of pulmonary arterial hypertension tends to outlive the initial infection. We don’t really understand the mechanisms underlying that. We know that inflammation is important but don’t fully understand how the initial infection and repeated infections sustain the disease. It is a topic which requires considerably more international attention and something that I know has been highlighted recently in articles that have been written by colleagues in the past 12 to 18 months. That aside， congenital heart disease is another important presentation of pulmonary arterial hypertension. In undeveloped and developing parts of the world there is still considerable work to be done to make inroads into the prevention and treatment of pulmonary arterial hypertension associated with congenital heart disease.