Introducer assembly particularly for balloon catheters

An introducer assembly, comprising:

• a catheter having a guide wire lumen extending between a proximal end and a distal end of the catheter and a side opening extending through an outer wall to the guide wire lumen, the guide wire lumen having a proximal portion extending from the proximal end of the catheter to the side opening and a distal portion extending from the side opening to the distal end of the catheter;
• a guide wire having a guide wire segment for occupying the distal portion of the guide wire lumen from the side opening to the distal end of the catheter, the guide wire segment disposed or disposable through the side opening to extend through and occupy the distal portion of the guide wire lumen from the side opening to the distal end of the catheter;
• wherein the guide wire segment for occupying the distal portion of the guide wire lumen from the side opening to the distal end of the catheter and the distal portion of the guide wire lumen are sized and configured so that a fluid agent injected distally through the proximal portion of the guide wire lumen exits the side opening when the guide wire segment is disposed through the side opening to extend through the distal portion of the guide wire lumen;
• and
• wherein the guide wire segment for occupying the distal portion of the guide wire lumen from the side opening to the distal end of the catheter has a solid cross-sectional area that is at least 70% of a cross-sectional area of the distal portion of the guide wire lumen so as to impede access of the fluid agent to the distal portion of the guide wire lumen.