Steering mechanism for catheters and methods for making same

A medical catheter comprising:

• a flexible tubular member having a lumen therein, the tubular member being adapted to be inserted into a vessel in the body of a patient;
• an elongated coaxial transmission line received within a lumen in the flexible tubular member, the coaxial transmission line including a center conductor, a shield and a dielectric that electrically insulates the center conductor from the shield, the shield having a distal end;
• an antenna carried by the coaxial transmission line;
• an electrically conductive shield termination attached to the distal end of the shield portion of the coaxial transmission line, the shield termination being arranged proximally of the antenna;
• and
• a steering wire that extends through the tubular member and is attached to the shield termination;
• whereby when the catheter is inserted into the vessel of a patient, the tip of the catheter may be steered by pulling on the steering wire.

A method of forming a microwave ablation catheter having a coaxial transmission line having a center conductor portion having a distal end, a braided shield portion having a distal end, and an antenna electrically coupled to the distal end of said center conductor portion of the coaxial transmission line, the method comprising the steps of:

• forming an elongated flexible tubular member having a tubular end that is sized suitably to be inserted into a vessel in the body of a patient, such that a first portion of the tubular member has a stiffness that is significantly less than the stiffness of the majority of the tubular member, the first portion of the tubular member being located near the distal end of the tubular member;
• securing an electrically conductive shield termination ring to the distal end of a braided shield portion of the coaxial transmission line;
• attaching steering wires to the shield termination ring;
• and
• inserting the coaxial transmission line and the steering wires into the flexible tubular member;
• and
• forming a cap over the antenna, the cap being sealed to the flexible tubular member.