A balloon catheter including an elongated shaft having an inflation lumen, a guidewire lumen, a proximal shaft section, and a distal shaft section with a balloon on the distal shaft section, the distal shaft section formed by an outer tubular member having an opening in a sidewall, and an inner tubular member having a distal portion in the outer tubular member and a proximal portion extending through the sidewall opening and along an outer surface of a portion of the outer tubular member located proximal to the sidewall opening, with polymeric filler material around the outer surface of at least the proximal portion of the inner tubular member. The inner tubular member preferably comprises a polymeric tube having a reinforcing coiled member embedded therein. Preferably, a crescent shaped portion of the inflation lumen extends along side the proximal portion of the inner tubular member.