Bosentan therapy for chronic thromboembolic pulmonary hypertension: a national open label study assessing the effect of bosentan on haemodynamics, exercise capacity, quality of life, safety and tolerability in patients with chronic thromboembolic pulmonary hypertension (BOCTEPH-Study) - Ulrich,S.; Speich,R.; Domenighetti,G. (Swiss Med Wkly, 2007)