Fixing device (315) to be anchored in surrounding tissue, the fixing device having an annular member (312), which member is provided with distal (313) and proximal (314) flange fingers arranged distributed around the periphery of the annular member (312), wherein the distal flange fingers (313, 314) are reversibly bendable, against a resilient force, from a position projecting outwards with respect to the annular member into a straightened position in which the projection of the distal flange fingers (313) on a radial transverse surface of the tubular member is essentially on or within the periphery of said annular member (312), wherein the flange fingers (313, 314) are open.
