Catheter having distal region for deflecting axial forces

A catheter for use with biological tissue, said catheter comprising:

• a sheath with a distal end region and a distal tip at the distal extremity of the distal end region, the distal end region having a deflection region proximal and proximate the distal tip and a working region proximal and proximate the deflection region
• the working region having an energy transfer device for transferring energy between the biological tissue and the catheter;
• a stylet disposed within the sheath, the stylet having a first portion located within the working region, the first portion having a first diameter, the stylet further having a second portion disposed within the deflection region of the sheath and passing therethrough, the diameter of the second portion of the stylet being less than the first diameter, the second portion of the stylet also having a preformed shape comprising a bend, the stylet disposed in the sheath such that the stylet causes the sheath to assume the preformed shape, the stylet formed of a shape-retentive and resilient material such that the first and second portions of the stylet change shape upon the application of force and upon the removal of force, return to their original shapes;
• and
• a tendon housed within the sheath and attached to the distal tip of the catheter, wherein movement of the tendon in the proximal direction decreases the radius of curvature of the first and second portions of the stylet.

A catheter for use in ablating tissue in the heart of a patient, the catheter having a sheath with a distal end region having a distal tip at the distal extremity of the distal end region, a deflection region proximal the distal tip and a working region proximal the deflection region, the catheter comprising:

• a plurality of electrodes mounted to the working region;
• a stylet having a distal end region having a preformed distal shape comprising a bend, the stylet being formed of a shape-retentive and resilient material such that the distal end region of the stylet changes shape upon the application of force and upon the removal of force, returns to the preformed shape, the stylet having a first portion with a first diameter in the distal end region proximal the bend and a second portion with a second diameter, less than the first diameter, in the distal end region distal the bend, the stylet housed within the sheath and attached to the distal end of the sheath such that the first portion is substantially coincident with the working region and the second portion is substantially coincident with the deflection region;
• and
• a tendon housed within the sheath and attached to the distal end of the sheath and positioned for axial displacement wherein movement of the tendon in the proximal direction decreases the radius of curvature of the first and second portions of the stylet.