Abstract: A device for ablating tissue within the body has an element with an energy emitting region helically wound about and along the axis of the element. The element emits energy to create a lesion in body tissue. A sheath of a non-energy emitting material is movable over the region to adjust the impedance of the region.

Abstract: A catheter having an elongated polymeric body with hollow encircling ring electrodes thereon and a method of forming the same are provided by the invention. Ring electrodes are each connected to an external electrical circuit by wires extending through the lumen, the wires each passing through an aperture through a wall of the body and being connected to an interior surface of the ring electrode. The tubular body of the catheter is expanded into a tight interference fit with the interior surfaces of the ring electrodes by heating the body to a temperature approaching its glass transition temperature to permit relief of internal stresses.

Abstract: An electrode tip assembly attachable to the end of a catheter for supporting a tip electrode for percutaneous insertion into a living body having a steering mechanism includes an elongated body bendable in response to external forces to steer the tip electrode. The body is connected at its distal end to the tip electrode. At least one steering wire is attached to the elongated body for transmitting bending force to the body from a remote control mechanism. An movable stiffening member, preferably in the form of a sleeve or rod provides a variable fulcrum for bending of the body in response to an applied bending force. A control stylet or sleeve extends through the catheter and is attached to the stiffening member for moving the stiffening member in a distal/proximal direction or for rotating it relative to the body.

Abstract: A system and method for cardiac diagnosis and treatment inserts the distal end of a catheter into a heart chamber. The distal end of the catheter supports at least one electrode. The catheter has a fluid flow conduit extending through it. The conduit has a valve that prevents fluid flow from the heart chamber into the conduit in response to in vivo pressure generated during heart systole and diastole. The valve permits fluid flow from the conduit into the heart at a pressure above the in vivo pressure. In use, the catheter locates the electrode in contact with a portion of the endocardium, and fluid is conducted from an external source through the conduit at a pressure above the in vivo pressure to flush the area surrounding the electrode.

Abstract: A balloon dilatation catheter having heating elements raise the temperature of the working surface of the balloon while the balloon is being inflated during an angioplasty procedure. In one embodiment, the balloon is provided with a thin electrically conductive layer in heat transfer relationship therewith preferably on the interior surface of the balloon. Electrical power at radio frequencies is preferred and a coaxial cable is employed to deliver such power to a conductive layer for heating the balloon. In another embodiment, the ballon itself is formed of electrically conductive material. A perfusion lumen may be provided through the balloon with one or more proximal inlet ports and one or more distal discharge ports in fluid communication with the lumen to allow blood to pass through the balloon when it is inflated during angioplasty procedures. This faciltiates the flow of oxygenated blood distally of the catheter when the balloon is inflated thus allowing for extended balloon inflations, e.g.