A tissue tunneler including an expandable attachment mechanism for securing a catheter. In one variation, the tissue tunneler comprises an elongate tunneler with a protrusion extending from the proximal end of the tunneler. An expansion mechanism is provided on the protrusion for insertion into the catheter. An oversleeve slidably disposed over the elongated tunneler may be provided to engage the expansion mechanism and trap the catheter between the oversleeve and the expansion mechanism. In another variation, the expansion mechanism may comprise of an expandable O-ring configured to engage an inner surface within a catheter.
