For example, mesh structures, similar to those used for stents or other endoprostheses, may be appropriate for use as a housing 12 in accordance with the present invention, such as that shown in FIGS. 6A and 6B. [0026] The housing 12 may be tapered, as shown, in order to facilitate implantation of the apparatus 10 within a tapered branch between a main passage and first and second branches, as sho