Abstract: Systems and methods for heating or ablating body tissue place in contact with tissue an electrode, which includes an exterior wall peripherally surrounding an interior area. A lumen conveys a medium containing ions into the interior area. At least a portion of the exterior wall of the electrode comprises a porous material sized to pass ions contained in the medium. The systems and methods transmit electrical ablation energy to the medium for ionic transport through the porous material to tissue. The systems and methods sense temperature proximal to where the electrode contacts tissue. The systems and methods control transmission of electrical ablation energy to the medium based, at least in part, upon the temperature sensed.

Abstract: Systems and methods sense electrical events about a selected annulus region of the heart to identify the location of an accessory pathway. The systems and methods establish a contact site between heart tissue along the selected annulus and a multi-electrode array having a generally circular shape that conforms to the circumferential geometry of the selected annulus region. The systems and methods maintain the site of contact between the electrode array and heart tissue, while conveying signals representing electrical events sensed by bipolar pairs of the electrodes in the selected annulus region, The systems and methods display the signals as graphic information that represents the time differences between the atrial and ventricular electrogram complexes sensed by bipolar pairs of the electrodes on the selected annulus region. The bipolar pair of electrodes displaying the least time separation between the atrial and ventricular complexes identifies the region of the accessory pathway.

Abstract: Systems and methods achieve defibrillation of a heart tissue region without resort to drugs or a painful electrical shock. The systems and methods sense electrical activity in the heart tissue region and generate an organization-indicating output. The organization-indicating output varies in relation to organization of heart rhythm in the heart tissue region. Use of the organization-indicating output guides the physician in organizing and entraining the heart tissue 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 for a catheter is bendable under the control of the user. The distal tip portion of the assembly is progressively less resistant to bending than the remaining portions. The variable stiffness is provided by tapering the width or thickness of a bendable spring component or otherwise providing a progressive change in bending characteristics by notching, dimpling or stepping the thickness of the spring.

Abstract: Enhanced electrical connections for electrodes are provided. In one implementation, an electrode body comprises a first electrically nonconductive layer and a second electrically nonconductive layer overlying at least a portion of the first layer. An intermediate region is formed between the first and second layers. An electrically conductive pathway extends within the intermediate region. An formed opening extends to the intermediate region, exposing a part of the electrically conductive pathway. An electrically conductive material is deposited on the second layer so that a part of the electrically conductive material passes through the opening to establish electrical contact between the electrically conductive material and the electrically conductive pathway.

Abstract: An imaging structure has a periphery adapted to selectively assume an expanded geometry and a collapsed geometry. The periphery of the imaging structure carries an array of spaced apart ultrasound transducers.

Abstract: Collapsible electrode assemblies and associated methods employing a structure having an axis and a distal end. The structure comprises a wall peripherally enclosing an interior. The structure is adapted to selectively assume an expanded geometry having a first maximum diameter about the axis and a collapsed geometry having a second maximum diameter about the axis less than the first maximum diameter. An electrically conductive material is carried by the wall, forming an electrode region adapted to conform to both the normally expanded geometry and the collapsed geometry of the structure. In one implementation, a flexing element in the interior of the structure bends within the interior along the axis of the structure to displace the distal end relative to the axis. In another implementation, a stilette element within the interior of the structure imparts axial force upon the distal end along the axis of the structure, thereby axially elongating or shortening the structure.

Abstract: A porous electrode assembly for tissue heating and ablation systems and methods includes a wall having an exterior peripherally surrounding an interior area. The assembly includes a lumen to convey a medium containing ions into the interior area. An element couples the medium within the interior area to a source of electrical energy. According to the invention, the wall includes at least two spaced apart zones. Each zone comprises a porous material sized to pass ions contained in the medium, to thereby enable ionic transport of electrical energy from the source through the medium and porous material to the exterior of the wall. In a preferred embodiment, the at least two zones are spaced apart by a third zone comprising a material that blocks passage of ions contained in the medium.

Abstract: Systems and methods for heating or ablating body tissue use a porous electrode structure in which the porous section of the structure occupies more of the distal region of the structure than the proximal region. In a preferred embodiment, at least 1/3rd of the proximal region of the structure is free of pores. The porous section can be either ultraporous or microporous.

Abstract: Systems and methods for heating body tissue place a multi-function structure having an exterior wall in contact with body tissue. The structure includes an array of electrically conducting electrode segments carried by the exterior wall. An electrically conductive network is coupled to the electrode segments, including at least one electrically conductive path individually coupled to each electrode segment. The systems and methods operate in a first mode during which the network is electrically conditioned to individually sense at each electrode segment local electrical events in tissue, such as electrical potentials, resistivity, or impedance. The systems and methods operate in a second mode during which the network is electrically conditioned, based at least in part upon local electrical events sensed by the electrode segments, to couple at least two electrode segments together to simultaneously transmit electrical energy to heat or ablate a region of body tissue.

Abstract: A flexible electrode support is bent to define an arcuate shape that extends beyond the distal end of an associated guide body. At least one of the ends of the support is free of attachment to the distal end. By moving the free end, a user can push upon or pull against the structure to alter its arcuate shape to assure intimate contact with tissue.

Abstract: Systems and methods examine heart tissue morphology using three or more spaced apart electrodes, at least two of which are located within the heart in contact with endocardial tissue. The systems and methods transmit electrical current through a region of heart tissue lying between selected pairs of the electrodes, at least one of the electrodes in each pair being located within the heart. The systems and methods derive the electrical characteristic of tissue lying between the electrode pairs based, at least in part, upon sensing tissue impedances. The systems and methods also sense the timing of local depolarization events in the tissue in which impedance is sensed and derive therefrom the propagation velocities of the sensed depolarization events. The systems and methods match the derived tissue electrical characteristics with the derived propagation velocities in spatial relation to the electrodes to characterize the morphology of the contacted heart tissue.

Abstract: Systems and methiods for heating or ablating tissue use a multifunctional electrode assembly. The electrode assembly includes a wall comprising an electrically conductive material peripherally surrounding an interior area. The wall has an interior surface facing the interior area and an oppositely facing exterior surface. A first element operatively associated with the exterior surface of the wall is adapted to carry out a first predetermined electrical transmitting or sensing function affecting body tissue. A second element operatively associated with the interior surface of the wall is adapted to carry out, independent of the first element, a second predetermined electrical transmitting or sensing function affecting body tissue different than the first predetermined electrical function.

Abstract: An electrode support structure has at least two spline leaves, each comprising an opposed pair of spline elements connected by a center web. Each web has a hole through which a pin assembly extends to join the webs of the spline leaves in a mutually stacked relationship. The spline elements radiate from the pin assembly in a circumferentially spaced relationship for carrying one or more electrodes. A hub member is over-molded about the pin assembly.

Abstract: Systems and methods for ablating body tissue using actively cooled electrodes deploy the electrode for contacting tissue to form a tissue-electrode interface. The systems and methods conduct ablation energy to the electrode for transmission by the electrode into tissue at the tissue-electrode interface. The systems and methods simultaneously cool the electrode while the electrode transmits ablation energy using a diode coupled to the electrode for conducting heat energy from the electrode in response to current flow from a current source.

Abstract: Tissue heating and ablation systems and methods use a porous electrode assembly with an electrically conductive surface. The electrode assembly includes an exterior peripherally surrounding an interior area. At least a portion of the wall comprises an electrically conductive material. A lumen conveys a medium containing ions into the interior area. According to the invention, at least a portion of the wall also comprising a porous material sized to pass ions contained in the medium. In a preferred embodiment, the electrode assembly further includes an element coupling the electrically conductive material to a source of electrical energy to transmit electrical energy. In this preferred embodiment, the electrically conductive material is also porous to pass ions contained in the medium. The assembly also preferably includes a conductive element coupling the medium within the interior area to a source of electrical energy to enable ionic transport of electrical energy by the medium through the porous material.

Abstract: Analog or digital systems and methods generate a composite signal derived from a biological event in a time-sequential fashion. The systems and methods input a first set of signals derived from a biological event using a first group of sensors during a first time interval. The systems and methods input a second set of signals derived from the biological event during a second time interval sequentially after the first time interval using a second group of sensors. The second group of sensors has at least one common sensor that is part of the first group and other sensors that are not part of the first group. The systems and methods time align the first and second sets of signals using the signals sensed by the at least one common sensor, thereby generating the composite signal. The systems and methods time align by shifting the first and second sets of signals either with or without computing a time difference between them.

Abstract: Systems and methods detect ancillary tissue within a tissue region targeted for ablation by locating a region to apply ablation energy to tissue targeted for ablation and applying energy within the region to stimulate selected ancillary tissue not targeted for ablation. The systems and methods sense when the selected ancillary tissue is affected by the stimulant energy within the region, thereby determining the presence of such ancillary tissue within the region. The systems and methods relocate the region until the selected ancillary tissue is not affected by the stimulant energy. The systems and methods then apply ablation energy in the region.

Abstract: A system and associated method ablate body tissue using multiple emitters of ablating energy. The system and method convey ablating energy individually to each emitter in a sequence of power pulses. The system and method periodically sense temperature at each emitter and compare the sensed temperatures to a desired temperature established for all emitters to generate a signal individually for each emitter based upon the comparison. The system and method individually vary the power pulse to each emitter based upon the signal for that emitter to maintain the temperatures at all emitters essentially at the desired temperature during tissue ablation.