A catheter assembly includes a wire guide having a helical outer wire and a non-helical core wire slidable within the outer wire between an advanced position and a retracted position. The outer wire includes a steering tip having a medium stiffness and a bending bias, and the core wire includes a higher stiffness and a straightening bias. The assembly further includes a catheter slidable over the outer wire to a steering configuration. A distal catheter end includes a compliant lower stiffness, and is adjustable in the steering configuration between a straight shape and a curved shape.