A system, comprising: - a catheter comprising: a sidewall that defines a lumen and an aperture extending around a circumference of the catheter from an outer surface of the catheter to the lumen; a distal portion located distal to the aperture and comprising: a projection that extends radially into the lumen, the projection and the side wall of the catheter opposite the projection being spaced by a distance, a reduced diameter portion having a diameter extending distally from a distal end of portion of the lumen; and - a waveguide disposed within the lumen, the waveguide comprising: a wire having a diameter; and a distal tip having a diameter, the distal tip being coupled with the wire and disposed in the distal portion of the catheter between the projection and the reduced diameter portion; - wherein a portion of the waveguide is exposed via the aperture to environment exterior to the catheter; - wherein the diameter of the distal tip is greater than the diameter of the wire; - wherein the diameter of the distal tip is greater than the distance between the projection and the sidewall of the catheter opposite the projection; and - wherein the diameter of the distal tip is greater than the diameter of the reduced diameter portion. - a catheter comprising: a sidewall that defines a lumen and an aperture extending around a circumference of the catheter from an outer surface of the catheter to the lumen; a distal portion located distal to the aperture and comprising: a projection that extends radially into the lumen, the projection and the side wall of the catheter opposite the projection being spaced by a distance, a reduced diameter portion having a diameter extending distally from a distal end of portion of the lumen; and a sidewall that defines a lumen and an aperture extending around a circumference of the catheter from an outer surface of the catheter to the lumen; a distal portion located distal to the aperture and comprising: a projection that extends radially into the lumen, the projection and the side wall of the catheter opposite the projection being spaced by a distance, a reduced diameter portion having a diameter extending distally from a distal end of portion of the lumen; and a projection that extends radially into the lumen, the projection and the side wall of the catheter opposite the projection being spaced by a distance, a reduced diameter portion having a diameter extending distally from a distal end of portion of the lumen; and - a waveguide disposed within the lumen, the waveguide comprising: a wire having a diameter; and a distal tip having a diameter, the distal tip being coupled with the wire and disposed in the distal portion of the catheter between the projection and the reduced diameter portion; a wire having a diameter; and a distal tip having a diameter, the distal tip being coupled with the wire and disposed in the distal portion of the catheter between the projection and the reduced diameter portion; - wherein a portion of the waveguide is exposed via the aperture to environment exterior to the catheter; - wherein the diameter of the distal tip is greater than the diameter of the wire; - wherein the diameter of the distal tip is greater than the distance between the projection and the sidewall of the catheter opposite the projection; and - wherein the diameter of the distal tip is greater than the diameter of the reduced diameter portion.