Abstract: A cardiac ablation apparatus for producing a circumferential ablation that electrically isolates a heart chamber wall portion from vessel such as a pulmonary vein extending into said wall portion comprises (a) an elongate centering catheter having a distal end portion; (b) an expandable centering element connected to said centering catheter distal end portion and configured for positioning within said vessel when in a retracted configuration, and for securing said elongate centering catheter in a substantially axially aligned position with respect to said vessel when said centering element is in an expanded configuration; (c) an ablation catheter slidably connected to said centering catheter said ablation element having a distal end portion, and (d) an expandable ablation element connected to said ablation catheter distal end portion.

Abstract: A cardiac ablation apparatus for producing a circumferential ablation that electrically isolates a heart chamber wall portion from vessel such as a pulmonary vein extending into said wall portion comprises (a) an elongate centering catheter having a distal end portion; (b) an expandable centering element connected to said centering catheter distal end portion and configured for positioning within said vessel when in a retracted configuration, and for securing said elongate centering catheter in a substantially axially aligned position with respect to said vessel when said centering element is in an expanded configuration; (c) an ablation catheter slidably connected to said centering catheter said ablation element having a distal end portion, and (d) an expandable ablation element connected to said ablation catheter distal end portion.

Abstract: A cardiac ablation apparatus for producing a circumferential ablation that electrically isolates a heart chamber wall portion from vessel such as a pulmonary vein extending into said wall portion comprises (a) an elongate centering catheter having a distal end portion; (b) an expandable centering element connected to said centering catheter distal end portion and configured for positioning within said vessel when in a retracted configuration, and for securing said elongate centering catheter in a substantially axially aligned position with respect to said vessel when said centering element is in an expanded configuration; (c) an ablation catheter slidably connected to said centering catheter said ablation element having a distal end portion, and (d) an expandable ablation element connected to said ablation catheter distal end portion.

Abstract: The efficacy of a lesion produced between a pair of ablation electrodes is assessed by analyzing the time it takes for a pulse of energy to travel from one electrode to the other. During a first time period, a first pulse of energy is applied to a first electrode. The time it takes for the pulse to conduct through the tissue to a second electrode is determined. During a time period subsequent to the first time, a subsequent pulse of energy is applied to the first electrode and the time it takes for the subsequent pulse to conduct through the tissue to the second electrode is determined. Changes in the conduction times are monitored by calculating the difference between consecutive conduction times and comparing the difference to a preset value. If the difference is below the preset value the lesion is considered adequate.

Abstract: An apparatus and method for treating atrial fibrillation with ablation therapy in which a stent is deployed within a pulmonary vein and tissue surrounding the stent is ablated with radiofrequency energy to stop discharges from ectopic foci in the vein from reaching the left atrium. The deployed stent can then be left in place to prevent stenosis of the vein as well as allowing repeat ablation procedures as needed.

Abstract: A surface covering including a primary layer of a porous polymer structure and a secondary surface covering one or both of a metallic element layer and a hydrophilic layer is positioned over the surface of an ablation electrode. The pores of the surface covering are sized such that blood platelets are prevented from contacting the surface of the electrode while physiological fluid is allowed to pass through and contact the electrode surface to hereby provide a conduction path for current from the electrodes. The surface covering may further include an electrically non-conductive and thermally conductive portion positioned over another portion of the electrode to prevent alternate or non-intended site ablations.

Abstract: A catheter system includes an outer catheter having a lumen and an inner catheter sized to fit within and slide through the lumen of the outer catheter. Both catheters may be introduced into an anatomical site through a single introduction path. At the distal-end region of each catheter is an electrode system. One electrode system is for mapping the site; the other is for ablating the site. The distal-end regions of one or both of the catheters may be linear shaped, circular shaped, or radially expandable. When the catheter system is deployed the electrode systems carried by the distal-end regions of the mapping catheter and the ablation catheter are movable relative to each other and tend to lie in planes substantially parallel to each other. Another catheter system includes two separate electrode systems on a single expandable member shaped so that both electrode systems come in contact with separate sites.

Abstract: A catheter includes a steering mechanism for manipulating the distal end of the catheter to obtain a plurality of deflection profiles, a torque transfer system to enhance torque transfer from the handle to the distal tip, and a support system to reduce undesirable deformation of the distal-end region during steering. The torque transfer system includes a flat ribbon within the relatively flexible distal-end region to enhance torque transfer through the distal-end region of the catheter. The support system includes a compression cage and longitudinal struts that are located within the distal-end region of the catheter. The support system can support axial loads and deflect laterally in the direction of the steering, thereby reducing the amount of stretching and compression of the catheter sheath within the deflecting region.

Abstract: A catheter includes a steering mechanism for manipulating the distal end of the catheter to obtain a plurality of deflection profiles, and a torque transfer system at the distal portion to enhance torque transfer from the handle to the distal tip. The steering mechanism includes two steering tendons. The steering tendons are attached to the distal-end region of the catheter. The steering tendons may be located approximately angularly aligned, thus causing the deflection profiles to be unidirectional. Alternatively, the steering tendons may be located angularly separated from each other, thus causing the deflection profiles to be bidirectional. In other aspects, the torque transfer system includes a flat ribbon within the relatively flexible distal-end region to enhance torque transfer through the distal-end region of the catheter.

Abstract: A catheter handle includes a steering controller with a self-locking mechanism to be used in conjunction with a steerable catheter shaft. A compression spring portion of the self-locking mechanism is located between the steering controller and a handle shell and causes alternating protrusions and recesses on the steering controller and on the handle shell to engage, thus locking the steering controller into a fixed position with the handle shell. Through a single-handed operation, an operator enables steering controller rotation by applying a force to the steering controller, which disengages the steering controller from the handle shell. The operator then adjusts the profile of a distal-end region of the catheter by rotating the steering controller. When the desired profile of the distal-end region of the catheter has been obtained, the operator removes the force from the steering controller and the spring decompresses to reengage the steering controller with the handle shell.

Abstract: A method of assessing the adequacy of contact between an ablation electrode and biological tissue within a biological organ having biological fluid therein includes the steps of positioning the ablation electrode proximal the biological tissue; positioning a reference electrode a distance from the ablation electrode; measuring the impedance between the ablation electrode and the reference electrode at a first frequency and measuring the impedance between the ablation electrode and the reference electrode at a second frequency. The percentage difference between the first-frequency impedance and the second-frequency impedance provides an indication of the state of electrode/tissue contact. In general, a percentage difference of at least approximately 10% serves as an indication of substantially complete electrode/tissue contact. A percentage difference in the approximate range between 5% and 10% serves as an indication of partial electrode/tissue contact.

Abstract: A tip electrode for an ablation catheter mounted at the distal tip of an elongated catheter body member has a distal-end region and a proximal-end region. A tip thermal sensor is located at or near the apex of the distal-end region and one or more side thermal sensors are located near the surface of the proximal-end region. The electrode is preferably an assembly formed from a hollow dome- shaped shell with a core disposed within the shell. The side thermal sensor wires are electrically connected inside the shell and the core has a longitudinal channel for the side thermal sensor wires welded to the shell. The shell also preferably has a pocket in the apex of the shell, and the end thermal sensor wires pass through the core to the apex of the shell. Spaces between the shell and the core can be filled with epoxy resin. Alternatively, the electrode is formed of a solid metal having a plurality of bores for positioning thermal sensors at the tip and near the surface of the electrode.

Abstract: A wire housed within a sheath is formed of a shape-retentive and resilient material having a curved shape at its distal-end region resulting in the catheter sheath having the curved shape. The catheter sheath also has an axially oriented tendon for causing deflection of the distal-end region. A movable outer sleeve surrounds the sheath and conforms the portion of the wire positioned within the outer sleeve to the shape of the outer sleeve. Upon relative displacement of the sheath and the outer sleeve a portion of the sheath extends beyond the outer sleeve and resumes its preformed curved distal shape thereby forcing the catheter distal-end region into the same curved shape. The operator may adjust the relative positions of the sheath and outer sleeve to changes the shape of the distal-end region. The operator may also axially move the tendon to adjust the radius or curvature of the distal-end region.

Abstract: A tip electrode for an ablation catheter mounted at the distal tip of an elongated catheter body member has a distal-end region and a proximal-end region. A tip thermal sensor is located at or near the apex of the distal-end region and one or more side thermal sensors are located near the surface of the proximal-end region. The electrode is preferably an assembly formed from a hollow dome-shaped shell with a core disposed within the shell. The side thermal sensor wires are electrically connected inside the shell and the core has a longitudinal channel for the side thermal sensor wires welded to the shell. The shell also preferably has a pocket in the apex of the shell, and the end thermal sensor wires pass through the core to the apex of the shell. Spaces between the shell and the core can be filled with epoxy resin. Alternatively, the electrode is formed of a solid metal having a plurality of bores for positioning thermal sensors at the tip and near the surface of the electrode.

Abstract: A catheter has a stylet formed of a shape-retentive and resilient material having a preformed curved shape at its distal end resulting in the catheter sheath having the preformed curved shape. The catheter sheath has a plurality of electrodes at its distal end for contacting selected biological tissue for imparting ablation energy thereto. The catheter sheath also has an axially mounted tendon for causing deflection of the distal end. The stylet material permits straightening the catheter sheath during insertion into the patient and advancing the electrodes to the target tissue. Upon removal of the straightening forces, such as by entry into a chamber of the heart, the stylet material resumes its preformed curved distal shape thereby forcing the catheter distal end with the electrodes into the same preformed curved shape.

Abstract: A catheter having a preformed distal shape for positioning a plurality of electrodes at a selected biological site includes a sheath having a preformed bend in the distal end region to distribute axial forces applied, in the distal direction, to the distal end region over a surface area of the distal end region proximal the distal tip. Also included in the catheter sheath is a stylet formed of a material capable of retaining a shape with the distal end of the stylet shaped in the preformed bend. Preferably, the preformed bend is approximately 45 degrees. Axial forces applied to the catheter are deflected to cause bowing of the catheter so that a larger surface area of the catheter contacts the tissue, rather than the smaller surface area of the distal tip. In other aspects, the portion of the sheath coincident with the preformed bend has a lower durometer, the stylet is more flexible by having a reduced diameter and the electrodes are located proximal to the preformed bend.

Abstract: A catheter has a stylet formed of a shape-retentive and resilient material having a preformed curved shape at its distal end resulting in the catheter sheath having the preformed curved shape. The catheter sheath has a plurality of electrodes at its distal end for contacting selected biological tissue for imparting ablation energy thereto. The catheter sheath also has an axially mounted tendon for causing deflection of the distal end. The stylet material permits straightening the catheter sheath during insertion into the patient and advancing the electrodes to the target tissue. Upon removal of the straightening forces, such as by entry into a chamber of the heart, the stylet material resumes its preformed curved distal shape thereby forcing the catheter distal end with the electrodes into the same preformed curved shape.

Abstract: A steerable catheter comprising a resilient deflectable body member having an expandable electrode array at the distal end thereof, and a manipulation handle attached to the proximal end of the body member, the handle including an array deployment device. A mandrel is movable through the shaft of the catheter by control movements at the handle to deploy the array or collapse the array as selected. A displacement compensation system is operatively connected to the mandrel such that when the array is expanded, the compensation system biases the mandrel so keep the array expanded, even during instances of deflection of the distal end. Similarly, the displacement compensation system biases the mandrel to keep the array collapsed when that configuration is selected, even during instances of straightening of the catheter. The displacement compensation system also compensates for overturning the control device in the handle to protect the array and deployment systems.