Variable stiffness electrically conductive composite, resistive heating catheter shaft

A variable stiffness electrically conductive catheter shaft comprising:

• at least one electrically conductive member;
• a plurality of layers of heat shrink polymer shrunk over said at least one electrically conductive member and coaxial therewith, said layers extending from the proximal end of said at least one electrically conductive member and terminating at different distances between said proximal end and said distal end;
• and
• an outer sheath of shrink wrap material shrunk over said at least one electrically conductive member and said plurality of layers of heat shrink material to thereby construct a tapered composite electrically conductive catheter shaft displaying a stiffness which varies over the length of the shaft.

A method for forming a variable stiffness electrically conductive catheter shaft comprising;

• passing at least one electrically conductive member at a predetermined speed through a first die which deposits a first polymer;
• passing said shaft upon which said first polymer has been deposited thereafter through a second die which deposits a second polymer;
• and
• quenching the resultant shaft to provide a desired amount of stiffness along the length of said shaft.

A method of constructing a composite electrically conductive catheter shaft comprising the steps of:

• winding about a catheter shaft including at least one electrically conductive member in a lengthwise fashion a helical strand of strengthening material;
• depositing a matrix about said strand in a predetermined position against said shaft;
• and
• forming an outer sheath to encapsulate said strands of said matrix and provide a smooth exterior shaped composite shaft.

A method of constructing an electrically conductive catheter shaft comprising:

• forming a hypo tube;
• grinding at least one taper into said hypo tube along its length;
• and
• adhesively attaching said hypo tube to at least one electrically conductive member extending therethrough, to thereby provide a composite shaft with variable stiffness along its length.

A method of constructing a composite electrically conductive catheter shaft comprising:

• passing at least one electrically conductive member at a first predetermined speed through a first die connected to a source of a first polymer to thereby deposit on said at least one electrically conductive member a predetermined thickness of said first polymer;
• varying the speed of said at least one electrically conductive member through said first die to thereby vary the thickness of said first polymer deposited on said at least one electrically conductive member;
• passing said at least one electrically conductive member at a second predetermined speed through a second die connected to a source of a second polymer to thereby deposit on said at least one electrically conductive member a predetermined thickness of said second polymer;
• and
• varying the speed of said at least one electrically conductive member through said second die to thereby vary the thickness of said second polymer deposited on said at least one electrically conductive member.