Abstract

A catheter, such as a balloon dilatation catheter includes an outer tabular shaft having a passageway extending therethrough. A flexible inner tube extending through the passageway is attached at its ends to the shaft to form an annular inflation lumen between the shaft and inner tube and a guidewire lumen extending through the inner tube. A dilatation balloon is mounted on the shaft and is in fluid communication with the inflation lumen. Upon aspiration of the inflation lumen and dilatation balloon via an inlet port, the inner tube expands against the outer shaft providing the guidewire lumen with a relatively large cross-sectional area for free movement of the guidewire. Upon injection of an inflation liquid into the inflation lumen, the inner tube collapses about the in-dwelling guidewire creating an inflation lumen having a large cross-sectional area enabling rapid inflation and deflation of the dilatation balloon. In another embodiment another flexible inner tube is provided to define a third intermediate annular lumen which may be pressurized to securely couple the catheter to the guidewire to increase the column strength of the assembly and enhance the pushability of the catheter through a stenosis.