Abstract: An implantable cardiac device wherein a reliability indicator is developed for cardiac classification based on the presence or absence of noise. If the classification is unreliable a robust therapy is applied until the cardiac condition is confirmed.

Abstract: An electrolytic capacitor with several conductive layer portions, including some anode layers and some cathode layers in alternating arrangement. A set of insulator layers is interleaved with the conductive layers, and the conductive and insulator layers are laminarly stacked with an anode layer being outermost on one surface. The stack is positioned adjacent a metal heat sink, with an outer insulator layer positioned between and closely contacting the stack and the heat sink. The cathode layers may be connected to the heat sink.

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, includes of a rapid response voltage threshold determination (RRVTD) 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. A method for operating a RRVTD circuit is also described.

Abstract: A system and method for a pacemaker are provided, for monitoring cardiac performance and adjusting a pacing regime to ensure hemodynamically optimal pacing therapy. The pacemaker includes a sensor for measuring a physiological parameter as an indicator of cardiac performance. A processing system dithers various programmable pacing parameters and notes the resulting changes in cardiac performance. The processor analyzes the changes in cardiac performance corresponding to changes in the pacing parameters and selects those parameters resulting in maximum cardiac performance. An activity sensor may be provided to allow the processing system to consider the activity level of a patient when determining a hemodynamically optimal pacing regime.

Abstract: An implantable cardiac device includes electrodes for sensing and pacing the heart, and optionally, defibrillation electrodes. The IECG with a noise component sensed in the heart is processed to derive raw sense signals indicative of whether the sensed QRS complexe's range is outside a certain range. This range is dynamically adjusted to compensate for the noise component. Preferably this range is defined by a threshold signal generator which generates a threshold signal including a first part which varies dynamically in accordance with a preset criteria and a second part which is at least equal to the peak amplitude of the noise.

Abstract: An improved pacemaker programmer and diagnostic system retrieves information stored within a pacemaker and analyzes the retrieved data in real time. The information stored within the pacemaker can be retrieved by means of a telemetry communication link. The system automatically identifies significant patient events (such as regions of increased heart rate, or loss of atrial or ventricular capture) and displays the significant events to the monitoring physician so that the physician is not required to scroll through the retrieved data to identify significant events. Furthermore, the system automatically suggests modifications to pacemaker parameters based upon certain retrieved data. The physician need only confirm the changes in order to modify the parameters within the pacemaker, so that the modification of pacemaker parameters is reduced to a "one step" process.

Abstract: An antitachycardia stimulation device that automatically adjusts its detection rate threshold as a function of a sensed physiological parameter indicative of cardiac rate. The implantable antitachycardia stimulation device includes heart rate detection circuitry and antitachycardia therapy circuitry for applying a specific antitachycardia therapy in the event that the detected heart rate falls within at least one tachycardia rate zone. The tachycardia rate zone is defined by a lower threshold limit, and may also be defined by an upper threshold limit if more than one rate zone is used. The lower threshold limit is automatically adjusted as a function of an independently sensed physiological parameter that predicts a normal or natural change in the heart rate. If more then one rate zone is used, other threshold limits may also be adjusted automatically as a separate function of the same sensed physiological parameter.

Abstract: Particularly applicable to implantable stimulation devices, a system is provided for laser-welding an electrically conductive elongate member, typically a lead, or elongate member, interconnecting operating components of a stimulation device. A bore is formed in a termination component for the slidable reception of the elongate member. Also formed in the termination component is an aperture in communication with the bore and having an axis which extends in a direction transverse that of the axis of the bore. The elongate member is positioned so it extends through the bore in the termination component and is thereby coplanar with and intersects the axis of the aperture.

Abstract: An implantable medical device, in the form of a cardiac defibrillator, has a support structure of molded thermoplastic foam surrounding the components of the device within a case to provide the components with shock and vibration resistance. The thermoplastic foam is produced by a process using dry nitrogen blowing, so as to be chemically inert. This prevents harmful outgassing of chemicals from the foam. The thermoplastic foam is a low density, crosslinked foam of polyethylene or polypropylene composition. The support structure includes an opposite pair of supports molded from the thermoplastic foam, so as to have facing portions configured to the irregular shape and size of the components. Each support is made by preheating an opposing pair of dies and a thermoplastic foam element, compressing the preheated foam element between the opposing dies, and heating for a predetermined time at a predetermined temperature, cooling the dies, and then removing the formed support from the dies.

Abstract: A special type of AV/PV hysteresis is provided in a dual-chamber pacemaker. A long AV delay is initially provided, thereby affording as much opportunity as possible for natural AV conduction to occur. Such long AV delay is automatically shortened should AV block occur. Periodic scanning for the return of AV conduction (absence of AV block) is performed so that the AV delay can be returned to its long value as soon as possible. In one embodiment, the pacemaker "learns" the natural conduction time (AR interval) of the patient and thereafter uses such learned natural conduction time as a reference against which subsequently measured AR intervals are compared to better distinguish conducted ventricular contractions from ectopic, pathologic, or other nonconducted ventricular contractions (e.g., PVC's).

Abstract: In a method and apparatus for removing data outliers in measured signals in an implanted medical apparatus, such as data outliers produced by GSM disturbance picked up by an implanted cardiac stimulator lead and superimposed on the sensed cardiac activity signal, the signal from the implanted lead is subjected to median filtering. The median filtering minimizes, or eliminates, the effect of highly aberrational data points in the incoming signal, without the necessity of actually removing the components in the signal produced by the disturbance from the incoming signal itself. Since no portion of the actual incoming signal is removed by the median filtering, the data integrity of the sensed cardiac signal is preserved.

Abstract: A heart stimulator, operable for single-chamber and/or dual-chamber pacing, includes a first unipolar electrical lead placeable in the atrium of a heart, and a second unipolar electrical lead placeable in the ventricle of the heart. In the heart stimulator, a differential detector is connected to each of these unipolar leads and detects a differential signal representative of cardiac activity between the atrial electrode and the ventricular electrode. The differential signal is supplied to decision logic which evaluates each of those outputs including using a morphology analysis, if necessary. Depending on the type of cardiac activity identified as a result of the evaluation, the decision logic supplies a signal to a control unit in the heart stimulator to cause the therapy administered by the heart stimulator to be altered as warranted. The decision logic may also derive a respiration signal from the differential signal, which can also be used to modify the administered therapy.

Abstract: A method is presented of welding an electrically conductive termination component having first and second opposed surfaces to an electrically conductive elongate member extending to a terminal end. The method comprises the steps of forming a substantially circular aperture through the termination component and defined by a rim having a diameter substantially equivalent to the transverse dimension of the elongate member. The terminal end of the elongate member is positioned proximate the termination component overlying the rim of the aperture such that the longitudinal axis of the elongate member is generally coplanar with the center of the aperture. Then, a laser beam is directed transversely of the termination component through the aperture therein toward and onto the elongate member to simultaneously melt the elongate member and the termination component in the region of the aperture and create a mixture of the molten material of both the elongate member and the termination component within the aperture.

Abstract: In a system for detecting changes in body posture, electrocardiograms are recorded. The recorded electrocardiograms analyzed are to determine changes in the body posture of a patient from changes in the morphology of the recorded electrocardiograms. The electrocardiogram analysis can be augmented by obtaining and analyzing an accelerometer signal as well.

Abstract: In an apparatus for terminating atrial fibrillation using pulses having an energy content which is the same as the energy content of conventional pacing pulses, stimulation pulses are respectively emitted by a number of electrodes disposed at different sites in or on a heart experiencing atrial fibrillation. When atrial fibrillation is detected, waveforms are measured at each of the electrodes, and the electrode having the waveform exhibiting the shortest interval between successive identifiable, cyclical waveform characteristics, such as successive P-waves, is selected as a first electrode for beginning an atrial defibrillation attempt. Stimulation pulses are emitted from the first electrode at a stimulation rate which is slightly shorter than the aforementioned shortest interval and the other electrodes are stimulated at a rate which is slightly shorter than the rate for the first electrode. All of the stimulation pulses are delivered starting at the latest local detection point in time.

Abstract: A heart stimulating device has pulse generators which can operate in either a first mode wherein the stimulation pulse energy is adjusted to a capture threshold of a patient's heart, or a second mode wherein the stimulation pulse energy is fixed. An evoked response detector senses IEGM signals to detect capture or non-capture subsequent to an emitted stimulation pulse. A noise detector detects as noise IEGM signals having predetermined signal characteristics. The noise detector, after having detected noise, sets the pulse generators to operate in the second mode. A lead arrangement connects the pulse generators, the evoked response detector, and the noise detector to a patient's heart.

Abstract: An implantable lead includes a distal portion carrying a tissue-stimulating electrode having an outer surface and an inner surface, at least a portion of the outer surface of the electrode being adapted to stimulate cardiac tissue. At least one of the surfaces of the stimulating electrode includes an overlay of a sulfonated thermoplastic elastomer/rubber for minimizing adhesion and tissue ingrowth while passing sufficient electrical current to stimulate the tissue. The overlay may comprise a coating, film, tube, sleeve or other encapsulation. Sulfonated block copolymers of styrene-ethylene-butylene-styrene (SEBS), styrene-ethylene-propylene-styrene (SEPS), styrene-isoprene-styrene and styrene-isobutylene-styrene are effective to inhibit the formation of thrombus at the shocking electrode. In addition, when these copolymers absorb body fluids, they swell and infiltrate the interstices of the electrode coils thereby inhibiting tissue ingrowth.

Abstract: A circuit module for use in an implantable cardiac stimulation device contains a plurality of stacked substrate platforms. Electrical components of a hybrid circuit structure are attached to respective mounting surfaces of the substrate platforms. Electrical connectivity between components mounted on separate platform levels is established by connecting the components via wire bonds or other means. The wire bonds pass through a slot formed in an upper level substrate and are attached to electrical contacts of an associated lower level substrate.

Abstract: A method for defibrillating a patient's atria with an implantable defibrillator having defibrillation synchronized to the atrial fibrillation waveform. The defibrillator is used to detect fibrillation in a patient's aria, monitor at least one atrial fibrillation signal across two electrodes, then deliver a high energy shock during a period of atrial fibrillation when the cycle lengths are stable within a desired measure of the cycle lengths monitored during the monitoring time period. The shock is then delivered synchronous with the R wave to avoid inducing ventricular fibrillation. The defibrillator also includes a timer so that if the desired cycle length stability is not reached within a specified time limit, the shock will be delivered with less stringent cycle length stability criteria.

Abstract: An electrical joint is provided between first and second electrical leads having different inner diameters. It comprises 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.