An angioplasty catheter comprising a catheter shaft having a proximal portion and a distal end, an angioplasty balloon attached to the shaft at the distal end, a balloon inflation lumen extending through the shaft and communicating with the interior of the balloon, a guidewire lumen extending through the shaft and through the balloon for receiving a steerable guidewire, the guidewire lumen having an outside wall, wherein the guidewire lumen has a proximal opening located at a point normally outside of the patient during use of the catheter for insertion of a guidewire into the lumen, and a side port adapted to permit passage of a guidewire into the lumen through the outside wall of the guidewire lumen, the side port located distally of the proximal opening and at a point normally inside of the patient during use, and guidewire removing means in the outside wall of the guidewire lumen extending from the proximal opening to the side port for permitting a guidewire in the guidewire lumen to be moved laterally from the guidewire lumen through the outside wall of the guidewire lumen. Also disclosed are a removable “Y” connector and methods for using the catheter and for exchanging catheters and guidewires during vascular catheterization procedures.