Catheter having improved rapid exchange junction

A rapid exchange type balloon catheter, comprising:

• a) an elongated shaft having an inflation lumen and a guidewire lumen, and
• i) a proximal shaft section comprising a metallic tubular member, defining a proximal portion of the inflation lumen;
• ii) a distal shaft section at the distal end of the proximal shaft section, having an outer tubular member defining a distal portion of the inflation lumen, and an inner tubular member defining the guidewire lumen in fluid communication with a guidewire distal port at the distal end of the inner tubular member and a guidewire proximal port at the proximal end of the inner tubular member, the outer tubular member having a fused section along which the inner tubular member is fused thereto and which extends from the proximal end of the inner tubular member to a location proximal to the distal end of the outer tubular member, and the outer tubular member having a thickened wall portion in the fused section thereof, the thickened wall portion having an inner periphery with a first segment which is fused to part of an outer surface of the inner tubular member and which extends around part of the inner periphery of the thickened wall portion, and a second segment which is not bonded to said inner tubular member and which extends around a remaining part of the inner periphery of the thickened wall portion;
• and
• iii) a reinforcing tube extending within at least a section of the outer tubular member thickened wall portion;
• and
• b) an inflatable balloon on the distal section having a proximal end secured to the outer tubular member, a distal end secured to the inner tubular member, and an interior in fluid communication with the inflation lumen.