 With a better understanding of the pathophysiology underlying pulmonary hypertension, novel therapeutic approaches have been developed during the past few years. These include a inhibition of the NO-cGMP-degrading type 5 phosphodiesterase PDE-5 and b antagonising the endothelin system Krum, Curr Opin Investig Drugs 2003. The goal is a dilatation of the abnormally constricted pulmonary arterial vessels by relaxation of the vascular smooth muscle cells with a reversal of pulmonary vascular remodelling Ghofrani, Pneumologie 2002. 