Abstract: A microwave ablation instrument including a transmission line having a first conductor and a second conductor suitable for the transmission of microwave energy. A horn antenna device is mounted to the end of the transmission line, and include an outer conductor and an inner conductor. The outer conductor of the horn antenna is electrically coupled to the second conductor of the transmission line, and includes a peripherally extending interior wall flaring outwardly to define a recess therein. The inner conductor of the horn antenna is electrically coupled to the first conductor of the transmission line and terminates in the outer conductor recess. The inner conductor and the outer conductor cooperate to emit an electromagnetic field sufficiently strong to cause tissue ablation in a direction generally away from the flared interior wall of the outer conductor.

Abstract: A catheter which may be configured as a loop during an ablation procedure, and a method of use for such a catheter, are disclosed. According to one aspect of the present invention, an ablation catheter includes a flexible distal member arranged to inserted into a first vessel in the body of a patient, and an elongated flexible tubular member with a distal portion which is coupled to a proximal portion of the flexible distal member. The elongated flexible tubular member has a flexibility that is greater than or equal to the flexibility of the flexible distal member. The catheter also includes a transmission line which is at least partially disposed within the elongated flexible tubular member. A proximal end of the transmission line is suitable for connection to an electromagnetic energy source. The catheter further includes a transducer that is coupled to the transmission line, and is arranged to generate an electric field sufficiently strong to cause tissue ablation.

Abstract: A catheter which may be configured as a loop during an ablation procedure, and a method of use for such a catheter, are disclosed. According to one aspect of the present invention, a method for medical treatment using an ablation catheter system that includes a catheter with a transmission line disposed within a flexible tubular member and a transducer that is located at a central portion of the catheter that is proximal to a distal tip portion of the catheter involves introducing the catheter into a first vessel of the body of a patient and past the heart of the patient such that the distal tip portion of the catheter at least partially passes out of the body through a second vessel while the central portion of the catheter is positioned within a cardiac chamber.

Abstract: A tunable microwave ablation catheter system is disclosed which matches the impedance of its power supply with the transmission line to minimize reflected power and optimize energy delivery to targeted tissues. The tuner itself may be located in the power supply, the transmission line or the antenna. Tuner mechanisms at these locations can change the antenna configuration, move material relative to the antenna or alter the waveguide. A controller monitors the catheter system operation. A method of medical treatment is disclosed where the impedances of the components of the systems are adjusted during use to compensate for impedance variations.

Abstract: An ablation catheter includes an elongated flexible tubular member adapted to be inserted into a vessel in the body of a patient. A transmission line is disposed within the tubular member and a transducer is coupled to the transmission line for generating an electric field sufficiently strong to cause tissue ablation. A shape memory wire is positioned at a distal portion of the catheter adjacent the transducer to facilitate straightening the catheter tip after use. In one preferred embodiment, the shape memory wire may a flat wire which is formed from copper beryllium, a steel alloy, or nickel titanium. In another embodiment, the transmission line of the catheter is a coaxial cable, and the transducer is a helical antenna coil that is adapted to radiate electromagnetic energy in the microwave frequency range. In yet another embodiment, the shape memory wire is positioned within the antenna coil. Methods for manufacturing and using such ablation catheters are also described.

Abstract: A variety of improved antenna arrangements for ablation catheters and methods for constructing catheter with these antenna arrangements are described. In various apparatus aspects of the invention, the catheter includes an elongated flexible tubular member adapted to be inserted into a vessel in the body of a patient. A transmission line suitable for transmitting electromagnetic energy is received within the tubular member. An antenna is coupled to the transmission line for generating an electric field sufficiently strong to cause tissue ablation. In one embodiment, the antenna takes the form of an antenna coil that is oriented such that its longitudinal axis extends substantially perpendicular to the longitudinal axis of the flexible tubular member. In another embodiment, a plurality of such laterally oriented antenna coils are provided at longitudinally spaced locations relative to the catheter axis. In other embodiments, the antenna coil is spirally wound.

Abstract: A variety of improved ablation catheters and methods for using such catheters are described. In one embodiment, the catheter includes a plurality of longitudinally spaced split electrode bands that are provided near the distal end of the catheter to monitor electrophysiological signals in the patient. The electrode bands each include a plurality of electrically isolated electrode segments. The number of electrode segments in each band may be widely varied, as may the number of electrode bands. In another embodiment, the catheter has a transducer that is movable longitudinally relative to the flexible tubular member. In one embodiment, the transducer is carried at the distal end of the transmission line and the transmission line is slideably received within the flexible tubular member such that the transducer can be positioned longitudinally relative to the electrode bands. In still another embodiment, the electrodes are ion implanted on the flexible tubular member.

Abstract: An ablation catheter with an anchoring tip extension includes an elongated flexible tubular member adapted to be inserted into a vessel in the body of a patient. A transmission line is disposed within the tubular member, and a transducer is coupled to the transmission line for generating an electric field sufficiently strong to cause tissue ablation. An anchoring tip extension, which is located at the distal end of the catheter, lodges into the wall of a cardiac chamber and serves to anchor the catheter both during an ablation procedure and during the process of conforming the catheter to the wall. In one preferred embodiment, the catheter includes a shape memory wire. In another embodiment, the transmission line of the catheter is a co-axial cable, and the transducer is a helical antenna coil that is adapted to radiate electromagnetic energy in the microwave frequency range. Methods for manufacturing and using such ablation catheters are also described.

Abstract: A tunable microwave ablation catheter system is disclosed which matches the impedance of its power supply with the transmission line to minimize reflected power and optimize energy delivery to targeted tissues. The tuner itself may be located in the power supply, the transmission line or the antenna. Tuner mechanisms at these locations can change the antenna configuration, move material relative to the antenna, or alter the waveguide. A controller monitors the catheter system operation. A method of medical treatment is disclosed where the impedances of the components of the systems are adjusted during use to compensate for impedance variations.

Abstract: A medical catheter steering construction is described that is particularly well suited for steering ablation catheters that utilize coaxial transmission lines. An elongated coaxial transmission line is received within a lumen in the flexible tubular member. An antenna is coupled to the center conductor of the coaxial transmission line. A shield termination is secured to the shield portion of the coaxial transmission line. A steering wire that extends through the tubular member to permit a user to steer the catheter during insertion is attached to the shield termination. With this arrangement, 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. In one embodiment of the invention, a distal portion of the tubular member has a stiffness that is significantly less than the stiffness of the majority of the tubular member to facilitate bending during steering. Suitable methods for making such catheters are also described.

Abstract: An ablation catheter is disclosed that include a mechanism for altering the impedance of the antenna during use in a controlled manner to tune the catheter. The impedance tuning may be accomplished in a variety of manners including altering the electromechanical configuration of the antenna and moving a material relative to the antenna or vice versa in order to vary the effective impedance during use. In a preferred embodiment, the ablation catheter transmits energy in the microwave frequencies and uses a coaxial transmission line as its waveguide. The antenna is preferably helical in nature and is carried by the distal end of the transmission line.

Abstract: A tuner system for a microwave power supply used in an ablation catheter system is disclosed. The tuner system includes a tuner arranged to facilitate matching the impedance of a power generator side portion of the catheter system with the impedance of a catheter side portion of the catheter system. A reflected power monitor is also provided for monitoring the amount of power that is reflected from the catheter during use. In a preferred aspect of the invention, the tuner is used in a power supply that includes a microwave power source and is used in conjunction with a catheter having a coaxial transmission line and a helical antenna. In a method aspect of the invention, a method for medical treatment using a microwave ablation catheter system is disclosed.