One embodiment is directed to a system for advancing a needle into a tissue structure, comprising: an elongate needle member having a tapered distal tip； an insertion member having proximal and distal ends, the distal end being coupled to the elongate needle member, and the proximal end being configured to be manipulated by an operator； and a tissue interface indentor member coupled to the insertion member and operatively coupled to the elongate needle member, the tissue interface indentor member comprising a distally protruding shape feature configured to contact one or more portions of the tissue structure adjacent to the distal tip of the elongate needle member and change an available angle of penetration between such portions and the distal tip of the elongate needle member as the distal tip is inserted into tissue structure.
