Abstract: An implantable cardiac device incorporating a processor and a waveform generation circuit incorporating a high voltage capacitor wherein the processor is adapted to charge the capacitor to an initial voltage, less than the peak voltage, and then measure the leakage current occurring across the capacitor at the initial voltage. If the leakage current occurring across the capacitor at the initial voltage is less than a preselected value, selected so that the corresponding leakage current across the capacitor when the capacitor is charged to the peak voltage is within an acceptable tolerance range, the processor then does not perform any further reforming of the capacitor.

Abstract: An implantable cardiac stimulator has a connector with at least two terminals, each terminal being connectible to an implantable electrode for delivering stimulation pulses to a heart and/or for sensing cardiac activity signals. The stimulator also has a switch and a control unit which operates the switch, so that one or both terminals are connectible to the pulse generator and/or to an input stage. The control unit identifies a position status for at least one of the electrodes in response to a signal received by the input stage at the time of implantation of the stimulator. The control unit also can select a terminal to be connected to the pulse generator, dependent on the established position status.

Abstract: An electrical joint is provided between first and second electrical leads having different inner diameters. The electrical joint is formed using an electrically conductive transition post including a disk-shaped a separation member, a first cylindrical mounting post having a first diameter integral with the separation member and extending away therefrom in a first direction, and a second cylindrical mounting post having a second diameter integral with the separation member and extending away therefrom in a second direction generally opposite the first direction. The separation member lies in a plane transverse to the longitudinal axis of the first and second mounting posts and has a diameter greater than that of either the first or the second mounting post. A first electrical lead is fittingly received on the first mounting post and a second electrical lead is fittingly received on the second mounting post. In each instance, the free ends of the electrical leads abut the separation member.

Abstract: Methods and apparatus for achieving atrial defibrillation in a heart. Atrial pacing is first conducted from a single pacing site so as to have the desired effect of maximizing the extent of phase-locked area of atrial tissue. Next, an ADF shock is introduced, if still needed, to achieve atrial defibrillation. ADFT energy requirements have been shown to be dramatically reduced on account of using a pacing rate set proportionally to the atrial fibrillation cycle length such that large areas of atrial tissues are phase-locked, and consequently atrial defibrillation can be effected in the patient with greatly reduced energy requirements for ADFTs.

Abstract: A dual-chamber implantable pacemaker is configured to operate in the DDD or DDDR mode with its AV (or PV) interval automatically set to be a small time interval less than the natural conduction time of a patient. The pacemaker shortens the AV (or PV) interval in response to a verified R-wave occurring within the AV (PV) interval, which it discriminates from an ectopic R-wave by requiring the occurrence of at least three consecutive R-waves or, alternatively, the occurrence of an R-wave having a morphology that matches the morphology of a reference R-wave stored in the pacemaker's memory. When the AV (or PV) interval is set to a value that is less than the natural conduction time, preemptive ventricular pacing.

Abstract: Methods and apparatus for achieving atrial defibrillation in a heart. Atrial pacing is first conducted from multiple pacing sites in a synchronous manner so as to have the desired effect of maximizing the extent of phase-locked area of atrial tissue. Next, an ADF shock is introduced, if still needed, to achieve atrial defibrillation. ADFT energy requirements have been shown to be dramatically reduced on account of using pacing rates set proportionally to the sensed atrial fibrillation cycle length(s) such that large areas of atrial tissues are phase-locked, and consequently atrial defibrillation can be effected in the patient with greatly reduced energy requirements for ADFTs.

Abstract: An abrasion resistant implantable lead is described including a protector for preventing abrasion to lead insulation. A helix-shaped protector can be placed around portions of the implantable lead to prevent frictional contact between the lead and the metallic casing of an implantable medical device, known as a pulse generator. The protector can have a cross-section and end-view of various shapes. The protector can be made of a flexible, elastomeric biocompatible material and can be coated by a hydrophilic surface to minimize the coefficient of friction between the protector and the casing of the pulse generator. The protector can have an inner cross-sectional diameter equal to or less than an outer cross-sectional diameter of the lead insulation, ensuring a snug fit. A toolkit for selecting, sizing and positioning the proper protector is described.

Abstract: A pacemaker has control circuits contained in an enclosure and a lead containing an electrical conductor connected to an electrode for delivering electrical stimulation pulses to a heart. The stretching of a wall in the ventricle, corresponding to adequate filling of the ventricle in the heart, is determined in order to identify a time of emitting the stimulation pulses. This stretching is measured indirectly by measurement of pressure in the ventricle using a pressure sensor disposed near the lead in the ventricle. The signal from the sensor is supplied via the lead to circuitry in the enclosure, wherein the signal is amplified and is supplied to an edge detector, which detects an increasing or positive edge of the signal.

Abstract: A method for treating arrhythmias which includes the steps of detecting an arrhythmia, and, in response to detection of the arrhythmia, delivering electrical energy to a targeted part of myocardial tissue in such a manner as to create a transient conduction block in the targeted part of the myocardial tissue without causing permanent damage to the targeted part of the myocardial tissue. The electrical energy can be continuous or pulsed RF, or continuous or pulsed DC. The detected arrhythmia can be atrial fibrillation, atrial flutter, ventricular fibrillation, or other type of arrhythmia. The targeted part of the myocardial tissue constitutes a critical part of the reentrant pathway or reentrant circuit required to sustain the detected arrhythmia. The electrical energy is preferably delivered via a catheter-based electrode which is in direct contact with the targeted part of the myocardial tissue, for either a prescribed period of time or until the arrhythmia is no longer detected (i.e., is terminated).

Abstract: An implantable atrial defibrillator for converting atrial arrhythmias into normal sinus rhythm includes a patient activated mode, a programmable safety timer, and means for deactivating the patient activated mode. The programmable safety timer starts counting down when AF is detected. If the safety timer times out before the patient activates delivery of an atrial defibrillation shock, the device will deactivate the atrial defibrillation function, and will not allow an atrial defibrillation shock to be delivered until the physician reactivates it with a programmer. This allows the physician to administer anticoagulants to the patient prior to atrial cardioversion. The preferred length of time between AF detection and lock out of the atrial defibrillation function is 24 hours.

Abstract: A device for determining the respiration rate and/or respiration depth of a patient includes a sensor for sensing heart sounds and an analyzer for analyzing the variation of the amplitude of the sensed heart sounds to determine the respiration rate and/or respiration depth from this amplitude variation. An apparatus for monitoring the respiration of a patient includes such a device and the analyzer is arranged to determine an anomaly in the amplitude variation of the sensed heart sounds as an indication of a respiration anomaly.

Abstract: A technique is presented for joining an elongated wound element having a plurality of filars and a mating component of a body implantable lead assembly. The wound element has a longitudinally extending interior passage and an end portion extending to a terminal end. The mating component includes a shoulder and an integral post extending away therefrom having an outer surface for receiving the end portion of the wound element, the diameter of the outer surface being smaller than that of the shoulder and larger than the diameter of the interior passage of the wound element. At a location spaced from the terminal end of the wound element, the end portion of the wound element and the receiving portion of the mating component are thermally fused together. This is performed by targeting a laser beam on the end portion of the wound element at a location spaced from the terminal end thereof to melt the wound element and the receiving portion of the mating component and thereby create a weld nugget.

Abstract: Preemptive tachyarrhythmia pacing is provided in an implantable cardiac-stimulation device, such as an implantable pacemaker or defibrillator, by modifying the operation of the implantable device in a way that minimizes the likelihood of occurrence of a tachyarrhythmia. The behavior modification is achieved through the use of an appropriate preemptive tachyarrhythmia pacing control routine stored within the memory of the device. Depending upon the needs of the patient, preemptive tachyarrhythmia pacing is invoked continuously or on demand. If invoked on demand, Preemptive tachyarrhythmia pacing is triggered only upon the sensing of one or more conditions suggest that the onset of a tachyarrhythmia is imminent. When thus invoked, preemptive tachyarrhythmia pacing remains invoked only for as long as the onset-of-a-tachyarrhythmia-is-imminent conditions persist.

Abstract: A heart stimulator has a pulse generator for producing stimulation pulses of varying amplitudes and varying durations for stimulating the heart of a patient, and an evoked response detector. The evoked response detector includes measuring and memory circuitry for measuring the charge delivered by a stimulation pulse. The measuring and memory circuitry determine and store, as a reference voltage, a charged voltage value related to the measured charge. Monitoring circuitry monitors the combined polarization and possible evoked response signal picked up from the patient's heart after the delivery of a stimulation pulse and derive a corresponding monitoring voltage value therefrom. A comparator compares the monitoring voltage value to the charged voltage value for determining, from the result of the comparison, the presence or absence of an evoked response.

Abstract: An implantable medical device has a housing containing an accelerometer which detects vibrations of the housing. The accelerometer generates a vibration signal in response to the detected vibrations, which is supplied to a signal processing unit. The signal processing unit generates, for each of a number of predetermined frequency ranges, a parameter value indicative of a defined attribute of the vibration signal. The signal processing unit forms a ratio between any two of these parameter values, and emits at least one status value dependent on this ratio. The status value is uniquely indicative of a predetermined type or level of cardiac activity, and the status values can be used as a control signal for controlling therapy, such as cardiac stimulation, administered by the implantable medical device.

Abstract: Methods and apparatus are provided for measuring the impedance of a patient's body. Pulse generating circuitry within a rate-responsive pacemaker is used to generate an impedance measurement signal that is applied to the body of the patient with conventional pacemaker leads. The impedance measurement signal contains a series of multiphasic impedance measurement waveforms, which have no net DC value and zero value after second integration. The impedance measurement signal allows the impedance of the body to be measured without interfering with external cardiac monitoring equipment such as electrocardiogram machines.

Abstract: An implantable stimulation device (ISD) for recording and displaying cardiac episode history for analyzing efficacy of cardiac therapy. The ISD applies anti-bradycardia therapy in patients who suffer from a slow heart rate, and antitachycardia therapy in patients who experience episodes of high heart rate and/or fibrillation. The ISD detects the occurrence of these episodes, applies the necessary therapy, and stores the chronology of these events in a special memory unit. An external device may be employed to telemetrically retrieve the stored data from the ISD memory unit, and display the data in a time-line fashion for analysis by a physician. The recordation of such data provides a valuable tool for the physician to track cardiac episode history and recommend the appropriate therapy for the patient.

Abstract: An implantable cardiac stimulation lead comprises an elongated electrical conductor with an electrode configured to deliver a tiered level of drug therapy to a patient. An insulative electrical sheath covers the electrical conductor and an electrical connector is coupled to the proximal end of the electrical conductor, adapted for connection with the pulse generator. An electrically conductive electrode is located at a distal end of the electrical conductor whose proximal end is adapted for connection to an implantable stimulation device, the electrode having an interior cavity and an axial bore extending between an exterior surface and the interior cavity. A matrix member, preferably composed of silicon rubber, is received within the interior cavity and contains a therapeutic drug.

Abstract: An evoked response detector for a heart stimulator determines evoked response in the presence of polarization. The heart stimulator has a pulse generator which produces stimulation pulses of varying amplitudes, and a lead adapted for introduction into the heart of a patient is connected to the pulse generator for delivering stimulation pulses to the heart. The evoked response detector includes measuring and memory circuitry for measuring and storing the electrode signals picked up by the lead in response to the delivered stimulation pulses, at least one of these stimulation pulses having a sufficiently high amplitude for obtaining capture. Each measured electrode signal contains two signal components, one of these signal components being proportional to the amplitude of the associated stimulation pulse and the other signal component being substantially constant, independent of the associated stimulation pulse amplitude.