Abstract: Electrophysiological activity can be mapped using sub-intervals of electrophysiological signals. An electroanatomical mapping system receives a plurality of electrophysiological signals (402), each of which spans an activation interval. For each signal, the system identifies an initial event time within the activation interval, such as by identifying a time of maximum signal energy (404), and defines a sub-interval about the initial event time (406). The system then analyzes the sub-interval to identify one or more electrophysiological characteristics of the electrophysiological signal (408) and adds a corresponding electrophysiology data point to an electrophysiology map (410). Advantageously, the sub-interval can extend outside of the activation interval, such that the instant teachings allow for capture and analysis of deflections that occur at or near the boundaries of the activation interval.

Abstract: A body-surface mapping system is disclosed that uses a plurality of electrodes to map at least a portion of a human torso without having to adjust the positions of the electrodes. The body-surface mapping system energizes groupings or regions of electrodes, then compares and adjusts the current driven through each grouping or region of electrodes to produce near-uniform fields. The electrodes of the body-surface mapping system may be interconnected by wires capable of sensing interelectrode distances, such that the system can reconstruct a detailed model of a patient's torso surface. The body-surface mapping system may also use a catheter in addition to the body surface electrodes to compute both endocardial and epicardial voltage distributions.

Abstract: A catheter includes a handle that advantageously limits the amount of torque that can be imparted to the body of the catheter. This advantageously reduces the likelihood of catheter failure, damage to tissue, or damage to medical devices introduced into the vasculature via the catheter. The catheter handle includes a grip portion that the practitioner manipulates in order to impart a torque and a torque transmitting portion operably coupled thereto that transmits the torque to the catheter body. A torque limiting mechanism decouples the torque transmitting portion from the grip portion, the body, and/or any pull wires when the torque imparted to the grip portion exceeds a torque threshold, thereby preventing excessive torques from being transmitted to the catheter body and/or pull wires. A practitioner may be able to adjust the torque threshold and may be able to disable the torque limiting mechanism.

Abstract: A body-surface mapping system is disclosed that uses a plurality of electrodes to map at least a portion of a human torso without having to adjust the positions of the electrodes. The body-surface mapping system energizes groupings or regions of electrodes, then compares and adjusts the current driven through each grouping or region of electrodes to produce near-uniform fields. The electrodes of the body-surface mapping system may be interconnected by wires capable of sensing interelectrode distances, such that the system can reconstruct a detailed model of a patient's torso surface. The body-surface mapping system may also use a catheter in addition to the body surface electrodes to compute both endocardial and epicardial voltage distributions.

Abstract: A system and method for assessing and displaying a degree of contact between a sensor, an electrode, and tissue in a body is provided. Values for the sensor are read, and a degree of contact is calculated. This degree of contact is displayed to a clinician in a variety of ways to indicate the degree of contact to the clinician. The system and method find particular application in ablation of tissue by permitting a clinician to create lesions in the tissue more effectively and safely.

Abstract: A body-surface mapping system is disclosed that uses a plurality of electrodes to map at least a portion of a human torso without having to adjust the positions of the electrodes. The body-surface mapping system energizes groupings or regions of electrodes, then compares and adjusts the current driven through each grouping or region of electrodes to produce near-uniform fields. The electrodes of the body-surface mapping system may be interconnected by wires capable of sensing interelectrode distances, such that the system can reconstruct a detailed model of a patient's torso surface. The body-surface mapping system may also use a catheter in addition to the body surface electrodes to compute both endocardial and epicardial voltage distributions.

Abstract: An electromagnetic accelerometer includes a rigid shell with a cavity in which two magnets are fixed at either and of the rigid shell and one magnet is allowed to move between the fixed magnets. The three magnets are arranged so that the movable magnet is suspended between the fixed magnets by magnetic forces from the fixed magnets. A coil of wire surrounds the shell and magnets. An acceleration of the accelerometer causes a displacement of the movable magnet with the cavity. As a result, an electrical current is induced in the coil of wire. The voltage in the coil of wire is proportional to the acceleration experienced by the accelerometer. The electromagnetic accelerometer is particular useful in an implantable pacemaker or defibrillator and can be included in either or both a lead or the housing of the pacemaker. Further, the accelerometer generates its own voltage in response to acceleration and the resulting electrical energy can be used as a power source.

Abstract: An implantable, rate responsive pacemaker, sensitive to impedance changes in the heart as an indicator of cardiac stroke volume or minute volume, wherein common interfering signals such as the intracardiac electrogram, myoelectric signals, pacing artifacts and other pacing after potentials are reduced or eliminated from the measurement of the impedance by the use of a biphasic test signal. The cardiac pacemaker has a signal injector which produces biphasic test pulses of similar duration and magnitude and of constant current, though of opposite polarity. The pacemaker also has a detector which senses voltage resulting from the applied biphasic current pulses in each phase. Since the injector and detector are separate circuits, they can be used with a variety of electrode configurations.