Abstract: During the telemetering of telemetry signals between an implantable medical device and an external programmer, the transmitter power of the implantable device is dynamically adjusted. The programmer measures the strength of the telemetry signals transmitted by the implantable device. A power control signal is generated as a function of the measured signal strength, and the transmitter power of the implantable device is set to a power level specified by the power control signal. For example, if the measured signal strength falls below a predetermined minimum signal strength threshold, power must be increased. This process is repeated until the measured signal strength satisfies a predetermined signal strength condition.

Abstract: A movable self-locking suture sleeve which can be securely positioned on the lead body of a pacing lead. The self-locking suture sleeve includes first and second cooperative rigid elements interconnected by a flexible tubing element. The tubing element is constructed from a woven mesh designed to constrict when stretched. A resilient element or spring is interposed between the first and second cooperative rigid elements, tending to force the cooperative rigid elements axially apart. Once the suture sleeve is moved into position, a self-locking feature allows the suture sleeve to secure itself to the lead body.

Abstract: A clinical programming system is disclosed for use with an implanted cardiac pacemaker to automatically determine the minimum pacing energy which is necessary to evoke an atrial depolarization. The system utilizes a series of pacing pulses of progressively decreasing energies to stimulate the atrium and detects following R-waves. The absence of an R-wave indicates the loss of atrial capture.

Abstract: An apparatus for measuring electrical activity in the heart, such as an ECG apparatus, has an input amplifier with multiple inputs to which the respective poles of electrodes introduced into a patient are intended to be connected. The input amplifier includes a sensing stage for sensing the impedance across the amplifier inputs after connection of the electrodes, in order to identify the poles which are in contact with the patient's heart. A display is connected to the input amplifier to graphically indicate which electrode poles are connected, and which are in contact with the heart.

Abstract: A battery powered cardioverter or defibrillator employing a DC-DC converter for charging high voltage output capacitors and for delivering biphasic cardioversion or defibrillation pulses through a bridge circuit including high and low side drive circuits under the control of a microprocessor controlled arrhythmia detection system. Upon the detection of an arrhythmia and the selection of cardioversion/defibrillation therapy, the charging of the high voltage output capacitors is commenced and the capacitor voltage enables a regulated voltage source for the high and low side drive circuits for the high power IGTs of each branch of the bridge circuit. High voltage switching transients are suppressed from re-triggering or otherwise affecting operation of the drive circuits. Fail safe circuitry disables operation of the drive circuits in the event that the first and second control signals are inadvertently provided simultaneously or overlap.

Abstract: A rate responsive pacemaker and method of pacing, having circuitry for controlling the rate of change of pacing rate in response to varying rate sensor signals. The pacemaker increments or decrements pacing rate each cycle, the change in rate being limited as a function of pacing rate, rate of change of sensor rate; the magnitude of the difference between sensor rate and pacing rate; whether prior cycles ended in sense or pace events; and/or a separate fast response sensor.

Abstract: Remote monitoring of cardiac electrical activity and/or pacemaker function under extensive control by personnel at a central station over the operation of a monitoring instrument at the patient's home, to thereby reduce reliance on active participation by the patient and to enhance useful information and suppress undesirable information in the signals transmitted between the home monitoring unit and the central station.

Abstract: A method and apparatus for converting an arrhythmia of a heart using a biphasic truncated exponential waveform wherein the first phase is of shorter duration than the second phase.

Abstract: An implantable lead for use with cardiac pacemakers, defibrillators and other long term implantable electrical devices intended for sensing or tissue stimulation, having a helically wound conductor with a surrounding tubular insulating layer of elastomeric material such as silicone or polyurethane and an additional coaxial tubular exterior biocompatible layer of porous PTFE having a microstructure of nodes interconnected by fibrils. The exterior tubular layer of porous PTFE may be fitted coaxially over the elastomeric tubular layer whereby the porous PTFE tubular layer is in longitudinal compression and the fibrils within the microstructure have a bent and wavy appearance. Any portion of the length of the porous PTFE tubing in longitudinal compression allows that portion of the length of the lead wire to be extensible to a controlled extent limited by the straightening of the bent fibrils within the porous PTFE microstructure.

Abstract: A multi-function implantable medical device having a plurality of microprocessors therein. The device, which may be capable of functioning as a pacemaker, cardioverter, and defibrillator, is equipped with two or more processors, which may be configured in a master/slave, peer, or other type of relationship. In one embodiment, primary device functions to be performed continuously are allocated to a dedicated, master processor, while advanced functions that may be only periodically required, are allocated among one or more slave processors. In this way, processing in the device is not limited to the relatively short refractory periods as in prior devices.

Abstract: Improved implantable defibrillator electrodes and methods of implanting such electrodes are disclosed. One embodiment of the defibrillator electrodes includes a flexible conductive mesh and non-conductive mesh. Another embodiment of the defibrillator electrodes includes a flexible conductive mesh, a non-conductive mesh and an insulator therebetween. A third embodiment of the defibrillator electrode compensates for the shape of a human heart. Methods for implanting the defibrillator electrodes include rolling an electrode and inserting the rolled electrode into a subxiphoid opening while thorascopically observing the insertion and manipulation of the defibrillator electrode.

Abstract: An implantable automatic atrial defibrillator powered by a depletable battery power source conserves battery power for extending the predicted life of the defibrillator by intermittently detecting for atrial fibrillation. The atrial defibrillator includes a real time clock which, at spaced apart predetermined times, causes heart activity data to be stored in a memory. Thereafter, a normally deactivated atrial fibrillation detector is activated for processing the stored data to detect for atrial fibrillation.

Abstract: An apparatus for producing heart defibrillation sequences formed of stimulation pulses and defibrillation shocks contains a unit for delivering pulses through an intracardiac or epicardiac electrode, normally for cardiac pacing, and defibrillator circuitry for delivering defibrillation shocks through defibrillation electrodes. The unit for delivering pacing pulses has an output stage which is capable of generating a stimulation pulse, delivered to the heart via the pacing electrode, having a higher energy content than a pacing pulse, but considerably less energy than a conventional defibrillation shock. A control unit is connected to the unit for delivering stimulation pulses and to the defibrillator circuitry for forming a defibrillation sequence consisting of stimulation pulses and defibrillation shocks. The control unit determines the timing for delivering the stimulation pulses and the defibrillation shocks.

Abstract: An apparatus reliably detects a depolarization activation wave of the heart. The apparatus includes a sensor in electrical contact with the heart for sensing electrical activity of the heart and including an amplifier for amplifying the sensed electrical activity according to a variable gain and providing a signal corresponding to the depolarization activation wave. The apparatus further includes an output circuit coupled to the sensor for producing an electrical output corresponding to the depolarization activation wave sensed by the sensor when the signal exceeds a threshold. The apparatus still further includes a control circuit coupled to the sensor and the output circuit for varying at least one of the gain and the threshold to maintain a predetermined sense margin between the sensed electrical activity and the gain and the threshold.

Abstract: A patient monitoring system utilizes a transmitter associated with each patient. The transmitter is worn by a patient and includes sensors operative to monitor vital signs of the patient. The transmitter transmits an allocated RF frequency which is particularly associated with that patient. A series of antennas are incorporated in a building, each antenna having its own signature signal. As the patient moves throughout the building, the antennas pick up the signals from the patient's transmitter and combines the antenna signature signal with the transmitted patient signal. This combined signal is then analyzed at a central location to determine the exact location of the patient due to the antenna signature signal which is modulated on the transmitted patient signal. Transmitted patient data is also decoded at the central station to provide a signal indicative of the vital signs of the patient.

Abstract: A lead for use with an implantable cardioverter/defibrillator system is disclosed. In the preferred embodiment, the lead combines a right ventricular endocardial electrode, a superior vena cava electrode and one or more atrial sensing electrodes on a single catheter lead. The distal end of the lead is transvenously implanted, typically through an incision in the cephalic or subclavian vein. The proximal end of the lead is then tunneled below the fascia to the location of the pulse generator. Ventricular sensing and/or pacing electrode(s) may also be included at the distal end of the combined lead to provide ventricular intracardiac electrogram sensing and bradycardia pacing.

Abstract: A method and a device for measuring the heartbeat pulse of a person during physical performance on an exercise device. The invention includes processing of a signal carrying pulse data and indicating the pulse frequency to the user of the exercise device. Included are the steps of programming the exercise device to provide a sequence of exercise to the performer, detecting and transmitting during the exercise a heartbeat pulse signal with electrodes and a transmitter attached to the body of the performer, receiving the transmitted pulse signal with a receiver connected to the exercise device, processing the received pulse signal, and calculating a mean pulse value during the performance and presenting the value to the performer.

Abstract: A method and apparatus for detection of the status of a cable termination. The cable is required to be terminated by being in contact with the body of a patient in a medical environment. The apparatus warns a user if the cable is disconnected from the patient. The status of the termination is established by applying a pulse of electrical energy to the cable and detecting the reflections produced in response to application of the pulse. A characteristic of the reflections is detected and compared with a predetermined characteristic to determine whether the cable is connected to the patient.

Abstract: A system including a process for enhancing detection of a pacing artifact in a patient having artificially paced myocardial contractions. The detection is accomplished by sensing seven EKG leads. Each lead provides a view of the heart from a different angle. The process relies on differentially amplifying the sensed pulses separately and passing the pulses through a filter. An algorithm is utilized to detect the noise level and the pacing artifact amplitude, and automatically select a proper trigger level. False pacing artifacts are eliminated by use of the software qualification. The principal is that if the hardware differentiator produces a signal due to noise or a pacing artifact, an interrupt is generated.

Abstract: A transcutaneous uterine contraction inhibiting device comprises a first plurality electrode positioned on an anterior side of an abdomen of a patient, a second plurality electrode positioned on the anterior side, and an electric current generator establishing electric current flow between the first plurality electrode and the second plurality electrode. The first plurality electrode is positioned above an upper portion of the uterus and extends laterally across the uterus. The second plurality electrode is positioned on a mid to lower portion of the uterus and also extends laterally across it. Further, a feedback unit can be provided for generating a signal indicative of any uterine contractions. The electric current generator then establishes an electric current in response to the signal from the feedback unit.