Abstract: A cardiac stimulation system is provided which delivers long term cardiac therapy without a personal supervision by a physician. The system includes a cardiac stimulation device implanted in a patient and an external device in constant or periodic communication with the cardiac device. The external device is used to control the pacemaker operation. The external device receives updates of the condition of the patient and the operation of the cardiac device and the therapy provided by the cardiac device. This information is transmitted by the external device over a standard telephone network which may consist of hardwired network, a cellular network, or a combination thereof to a remote control device operating near the physician and/or a monitoring station used for monitoring and data logging information from a plurality of patients. The cardiac device, through the external device can also communicate directly and exchange information with the patient over an RF channel.

Abstract: A lead sealing device that resides within the connector cavity of a pacemaker or defibrillator intended to prevent fluid intrusion by automatically sealing the lead lumen when the lead connector is inserted. The sealing mechanism may be in the form of a silicone disk located at the base of the space defined by the connector cavity in which the lead is inserted to make electrical and physical contact. It may be fixedly located at the bottom of the connector cavity, or may be a movable plug located within the connector cavity at a location other than the bottom of the cavity, such as adjacent to the connector block. In that case, the pin will make contact with the movable plug immediately after passing through the connector block, and will remain in contact with and seal the lead lumen while the pin and plug are further advanced to bring the pin into its final location to make electrical contact with the connector contact.

Abstract: A monitoring system is provided that monitors the condition of a patient by analyzing physiological data received from implantable medical devices. The monitoring system has at least one monitoring unit, which preferably is suitable for stand-alone operation, or which may be connected to a central monitoring station. The monitoring unit, which receives the physiological data from the implantable medical devices via telemetry, determines whether a patient's physiological condition warrants attention. If the patient's condition is determined to be abnormal, the monitoring unit generates an audible alarm signal or generates an alarm signal that is transmitted to the central monitoring station.

Abstract: An implantable cardiac stimulation device contains a high voltage defibrillating unit. A protection circuit is connected to the defibrillating unit to guard against excessive current during a high voltage discharge. The protection circuit prevents damage to the defibrillation unit and to the associated heart tissue. The defibrillation current is monitored by the protection circuit and if excessive, the defibrillation current is reduced by routing the current through an additional impedance. The protection circuit operates in real-time to remove the additional impedance if the defibrillation current returns to a safe level. A memory device attached to the protection circuit records the event of an excessive defibrillation current.

Abstract: In a dual chamber implantable pacemaker, the peak amplitude of the atrial intrinsic signals are monitored and used to generate a short term and a long term indicia indicative of the intrinsic signals' variability and deviation from normal sinus rhythm peak amplitudes. The two indicia are combined to generate a single indicia which is then used to categorize the state of the atrium as one of several conditions such as flutter/flubber, coarse atrial fibrillation or fine atrial fibrillation. The categorization is used by a microcontroller for generating the proper pacing pulses and may also be used as a criteria for mode switching between a first mode wherein synchrony between the atrium and ventricle is maintained and a second mode pacing is performed at a fixed rate or one determined by the metabolic indicator.

Abstract: A cardiac event and arrhythmia detection system and method detects arrhythmic cardiac activity or other information from an electrogram signal of a heart. The system senses the electrogram signal through an electrogram lead, preliminarily processes the signal, and converts it to a plurality of discrete digital signals, each of which represents the magnitude of the electrogram signal at a prescribed sample time. The discrete digital signals are applied to both a cardiac event detector and a morphology detector. The morphology detector detects selected changes in the morphology (shape) of the electrogram signal, wherein such changes automatically control the sensitivity (gain and/or threshold) used to detect cardiac events. The occurrence of a prescribed amount of change in the detected morphology over time indicates the occurrence of a prescribed arrhythmic cardiac condition.

Abstract: This invention provides a therapy decision support system and method for guiding physicians and medical technicians in optimizing a set of adjustable parameters that define the operating characteristics of implantable cardiac stimulating devices. The invention also provides an implantable cardiac stimulating device programmer which can furnish therapy decision support as well as telemetric data retrieval and telemetric programming capabilities.

Abstract: A method and system are provided for organizing, viewing and manipulating information in an implantable device programmer. The information includes programmable parameters which are divided into key parameters and subordinate parameters. Each key parameter has one or more associated subordinate parameters which are displayed when the user selects the key parameter, but which are not displayed when a different key parameter is selected. Subordinate parameters can be made sticky by the user. A sticky subordinate parameter is displayed regardless of whether or not the user has selected its associated key parameter. Certain parameters are linked so that when the user selects any one of the linked parameters, all linked parameters are displayed. Certain parameters are designated as inactive because of interactions with other parameters.

Abstract: A body implantable flexible lead assembly, adapted to transmit electrical pulses between a proximal end of the lead assembly and a distal end of the assembly to stimulate selected body tissue, includes a tubular, insulating housing connecting the proximal and distal ends of the assembly and having a central, longitudinal axis. At least two coiled, insulated conductors extend between the proximal and distal ends of the assembly for transmitting electrical signals, the coils of the at least two insulated conductors having substantially the same diameter. One of the coiled conductors is rotatable about the longitudinal axis relative to the other coiled conductor(s) and has a proximal end and a distal end.

Abstract: An electrophysiology diagnostic device generating a high voltage (HV) pulse of a predetermined shape, which device is electrically connected to a patient's heart, i.e., a load resistance and which device includes a microprocessor and a load resistance measuring device, consists of a rapid response voltage threshold determination (RRVTD) circuit and a variable capacitance emulation (VCE) circuit. The RRVTD circuit receives an actual signal corresponding to the HV pulse waveform, compares the actual signal with a desired signal and produces an error signal when the actual signal deviates from the desired signal by a predetermined threshold value. The VCE circuit, which is capable of emulating a selected capacitance C, includes a fixed capacitor C.sub.0, and first and second branch circuits including respective resistors R.sub.1 and R.sub.2 and corresponding switching elements, connected in parallel with the load resistance R.sub.L.

Abstract: A graphic user interface for a cardiac implant, such as an implant programmer, includes image generators for generating multiple images on a screen, each image corresponding to as representation of a parameter related to the operation of the implant or a cardiac function, and an indicia generator for superimposing on the images an indicia indicative of the interrelation between the parameters. The indicia allows a user to obtain a clear understanding and appreciation of the cause and effect rules between various cardiac parameters and/or functions, the parameters or functions could be actual, i.e., obtained from the implant and/or the patient's heart, or they can be simulated to provide the user an indication on how the pacemaker will operate under these simulated conditions parameters.

Abstract: An implantable lead for use with an implantable pacemaker/cardioverter/defibrillator. Since irradiation from a radioisotope source is capable of inhibiting the growth of hyperproliferating cells as compared with normal cells, a radioisotope material which is incorporated into the lead can be used to decrease the rate of fibrotic growth. The radioisotope may be located inside the lead, alloyed into the metal from which the lead electrode or conductor is made, molded into rubber portions of the lead, or coated onto the conductor or electrode's surface. Beta emitting radioisotopes would be best suited as a radioactive material because of their comparatively short range of action within human tissue.

Abstract: An electrode cable for implantation in a body cavity has a tube made of a biodegradable, biocompatible polymer material attached to the exterior of the cable, the tube forming a channel for a stylet.

Abstract: A diagnostic device makes use of knowledge based rule system for making a prognosis of a cardiac malfunction based on operation parameters and/or patient characteristics received from a cardiac implant. The device generates a symptoms vector from the information received from the implant, and using the expert rules to generate an appropriate prognosis. Both pathological problems and programming problems may be detected in this manner.

Abstract: A method of operating a pacemaker and a pacemaker system that cuts short a pacemaker-defined refractory time period whenever capture is not achieved. The pacemaker generates a cardiac stimulation pulse, and in response thereto, initiates an evoked response detection time period and a refractory time period. If an evoked response occurs during the evoked response detection time period, capture is presumed. If an evoked response does not occur during the evoked response detection time period, then capture is not achieved and the refractory time period is terminated, or cut short, thereby lengthening the window during which natural cardiac activity may be sensed. In the event natural cardiac activity is not detected following the termination of the refractory time period, a backup stimulation pulse may be generated.

Abstract: A method for characterizing the degree of similarity between phase space representations of trajectories of different dynamical systems. This method provides a computationally efficient technique for comparing different dynamical systems, or different dynamics exhibited by the same system. A first trajectory is designated as a template against which other trajectories are compared. A test trajectory is characterized by providing a measure based on determining the smallest distance between each point of the test trajectory to the template and then determining the largest of these smallest distances. The similarity of the two trajectories is quantified by establishing a lattice or grid for the phase space. For each lattice point, the distance, as given by a metric defined for the space, is calculated to the nearest point of the template trajectory. The minimum distance is retained and associated in a memory for each lattice point.

Abstract: A method and apparatus for performing electrophysiologic testing on a patient's heart using an implantable pulse generator system. The system includes an implantable pulse generator such as an implantable cardioverter-defibrillator having high voltage capacitors for storing electrical energy to defibrillate the patient's heart, a means for inducing a cardiac arrhythmia, an electrode system for discharging the stored energy into the patient's heart, and an external programmer for communication with and command of the implantable pulse generator. The method comprises the steps of charging the capacitors to a selected energy level upon command from the external programmer, inducing fibrillation in the patient's heart following the charging step, and discharging the capacitors through the electrodes into the patient's heart to defibrillate the patient's heart. The method and system provides flexibility in electrophysiologic testing by allowing the physician to control the time of delivery of high voltage therapy.

Abstract: A medical implant contains a magnetic field detector with a sensor whose capacitance changes in the presence of a magnetic field with a predefined strength, and a capacitance-controlled unit connected to the sensor. The capacitance-controlled unit sends a measurement signal to a detection unit. If a measurement signal parameter affected by capacitance exhibits a specific change over a predefined period of time, a detection signal is generated by the detection unit to indicate the presence of a magnetic field. The sensor's capacitance also changes when the sensor moves, and this is utilized for measuring activity in an activity measurement circuit connected to the capacitance-controlled unit and for generating an activity signal on the basis of the measurement signal.

Abstract: An implantable suture sleeve for use with an implantable lead with a pacemaker/cardioverter/defibrillator lead. Since irradiation from a radioisotope source is capable of inhibiting the growth of hyperproliferating cells as compared with normal cells, a radioisotope material which is incorporated into the lead can be used to decrease the rate of fibrotic growth. The radioisotope may be located inside the suture sleeve, alloyed into or coated onto the metal from which a wire or coil within the suture sleeve is made, or molded into the rubber of the suture sleeve. Beta emitting radioisotopes having a half-life between 1 and 100 days would be best suited as the radioactive material due to their comparatively short range of action within human tissue, and because of their comparatively short half-life.

Abstract: An appliance for fastening one or more electrode leads in a connector unit of an implantable medical device, for example a heart stimulator, is formed of a wire- or strip-shaped resilient locking member, which is arranged to be inserted and fixed in a cavity in a connector unit, and which is shaped to clampingly engage diametrically opposed circumferential parts of the casing of each electrode lead.