Method of inserting a balloon catheter

The method of inserting a catheter into the arterial system of a patient which comprises the steps of inserting said catheter into the arterial system of a patient;

• increasingly pressurizing a lumen of said catheter through a first pressure, to cause a portion of said catheter having a work-hardening capability and having a diameter to elastically expand to such a degree that sufficient work-hardening takes place under said pressure in the expanding catheter portion, to cause the diameter of said catheter portion to substantially cease its expansion in a first pressure range increasing from said first pressure;
• and terminating the increase of said pressure in said first pressure range, whereby said catheter portion assumes a first, predetermined, maximum diameter;
• and thereafter increasingly pressurizing said catheter lumen through a higher second pressure to cause said catheter portion to resume said elastic expansion and where the diameter of said catheter portion again substantially ceases to expand with increasing pressure in a second pressure range increasing from said second pressure, and again terminating the increase of said pressure in said second pressure range, whereby said catheter portion assumes a second, predetermined maximum diameter.