Lung transplantation 
Lung transplantation was historically the treatment of choice for severe PAH and remains treatment of choice if medical treatments are insufficient [197]. However, this particularly heavy surgery can be proposed only to a minority of patients suffering from PAH. Moreover, long-term benefits remain disappointing with approximately 50% survival at 5 years [275]. Early mortality is mainly related to infectious complications whereas late mortality reflects mostly chronic rejection such as obliterating bronchiolitis. Mono-pulmonary transplantation had good long-term results [276,277], but most centers currently prefer bi-pulmonary transplantation which has less post-operative complications [278]. Cardiopulmonary transplantation may be necessary for patients presenting with terminal right heart failure or complex congenital heart disease [279]. In conclusion, PAh is a rare group of diseases that shares broadly similar pathological features, pathophysiology and clincal presentation. The discovery of the central role of endothelial dysfunction leads to the development of specific PAH therapies including prostanoids, endothelin receptor antagonists and PDE-5 inhibitors. Even these therapeutic advances, no cure of the disease can be achieved and the prognosis remains unsatisfactory.