Double-lumen infusion catheter including: a shaft having proximal section, distal section, and intermediate section therebetween； first and second lumens extending along a length of the shaft and having arc shaped wall therebetween； and an inflatable member provided distally to intermediate section, and over the distal section. First lumen has cross section larger than cross section of second lumen and is configured to receive a guidewire therethrough and allow fluid flow via an unobstructed portion of first lumen. Unobstructed portion is formed along guidewire outer surface, between guidewire outer surface and inner wall of first lumen, and extends from an inlet at proximal end of intermediate section to an outlet at distal end of intermediate section. First lumen is narrowed to approximate a first diameter in shaft proximal and distal sections, and is widened to approximate a second diameter greater than first diameter in the shaft intermediate section.
