Catheter with a convertible proximal catheter shaft

A balloon catheter includes an inflation shaft and an elongated guidewire shaft. A relatively short, distal portion of the guidewire shaft is attached to, or enveloped within, a distal portion of the inflation shaft. A proximal portion of the guidewire shaft is detached from and independent of a proximal portion of the inflation shaft. The detached portion of the guidewire shaft contains perforations at pre-determined points along its length that define removable segments thereof. The removable segments remain attached to the guidewire shaft under normal conditions, but may be torn away from the guidewire shaft to provide access to a guidewire within a guidewire lumen thereof.