Patient enrollment and data acquisition is to be carried out on a prospective basis. It is planned to enroll a total of 50 patients with advanced heterogeneous emphysema. After decision to undertake endoscopic lung volume reduction by valve implantation patients will be randomised to two treatment arms. 25 patients receive unilateral IBV treatment or unilateral EBV treatment in each case. All patients will undergo treatment at one study centre in Heidelberg.