Catheter with a dual lumen monolithic shaft

A method of forming a multi-lumen catheter comprising:

• extruding a first material to faun an inner core with a first lumen and a second lumen defined therein, the first lumen having a first lumen cross-section and the second lumen having a second lumen cross-section;
• extruding a second material generally surrounding the inner core to form an extrudate having an outer layer of the second material surrounding the inner core of the first material, the extrudate having an outer cross-sectional dimension;
• drawing a length of the extrudate at a varied speed to vary the outer cross-sectional dimension along the length thereof;
• and internally pressurizing the first lumen and the second lumen, respectively, while drawing the extrudate to maintain the first lumen cross-section and the second lumen cross-section;
• and
• cooling the extrudate to form a monolithic elongate tubular shaft member having a proximal end, a distal end and a longitudinal length therebetween, the tubular shaft member having an outer cross-sectional dimension that varies along the length of the tubular shaft member.