In some embodiments, without limitation, the invention comprises a catheter having an elongated housing with a channel disposed therein. A laser delivery member is movable and at least partially disposed within the channel. A ramp is disposed within the housing at an angle to its central axis and proximate to its distal end. The ramp is adapted to move the distal end of the laser delivery member outwardly from the central axis of the housing. A guidewire biases the distal end of the laser delivery member generally inwardly toward the central axis of the housing. In some embodiments, without limitation, the offset of the central axis of the tip of the laser delivery member from the central axis of the housing is determined by adjusting the extent to which the laser delivery member travels on the ramp, and disposition of the laser delivery member on the guidewire maintains the offset tip substantially parallel to the central axis of the housing. Thus, in accordance with the invention, the distal end of the laser delivery member may be biased in a desired direction or offset, permitting ablation of an area larger than the area of the distal end of the catheter.