A balloon angioplasty catheter system comprising a flexible guide wire, balloon catheter and slide handle. The balloon catheter has a shaft with a guide wire lumen that includes a guide wire removal slit which extends along a portion of the shaft. The slide handle is configured to open the slit as the handle slides along the catheter. The handle includes a separate passage for the catheter and guide wire and is provided with a fitting for connecting the handle to the "Y" adaptor of a guide catheter. The system provides a arrangement with the advantages of both an over-the-wire and monorail catheter.