Abstract: In a method and an apparatus for detecting the status of a battery in an implantable heart stimulator, the battery impedances measured and an increased value of the measured impedance is detected, from which an impedance based value of the remaining battery capacity is determined. The increase in impedance is analyzed to determine whether the impedance increase is a reliable indicator of the remaining battery capacity. If it is determined that the impedance increase is not reliable for determining the battery capacity, the total charge depletion of the battery is measured and a charge depletion-based value of the remaining battery capacity is determined.

Abstract: An implantable heart stimulator has an electrode lead adapted to detect electrical heart signals and a cardiac activity sensor connected to the electrode lead for detecting heart signals above a sensitivity level. A heart signal classifier is also connected to the electrode lead, and classifies the incoming heart signals in a histogram with regard to their respective peak amplitude values. The heart signal classifier has a sensitivity level lower than the sensitivity level of the cardiac activity detector so that incoming heart signals are included in the histogram data which are below the level that would be detected by the cardiac activity detector. An analyzer in communication with the classifier and the activity detector analyzes the histogram data and adjusts the sensitivity level of the activity detector dependent on the histogram data.

Abstract: An apparatus for treating an infection which may occur in the biofilm which surrounds an implanted cardiac stimulation device, e.g., a cardioverter-defibrillator)ICD) or pacemaker. Such inflections are relatively untreatable by conventional antibiotics treatments. Thus, explanting of the implanted devices may be required. Accordingly, the present apparatus provides an electrical treatment that enables a biocide, i.e., an antibiotic, to successfully treat the infection within the biofilm and thus avoid the necessity to explant the device. Furthermore, the present invention provides this electrical treatment in a manner to not interfere with the stimulation pulses of the cardio stimulation device by alternatively delivering current pulses during atrial and ventricular refractory periods or a high frequency square wave at a frequency that exceeds the frequency response of the heart muscle.

Abstract: An implantable heart stimulator has an electrically conductive housing containing a pulse generator, with an electrode lead connected to the housing. The electrode lead has a proximal portion extending substantially from the housing to a location, after implantation, which is beyond the entry of the lead into the venous system and before the entry of the lead into the superior vena cava. A current source supplies an infection control current between the housing and an electrically conductive surface on the exterior of the proximal portion of the electrode lead, for counteracting bacterial growth. The housing may have a header to which the electrode lead is connected, in which case the header is provided with an electrically conductive surface as well, which can serve as an electrode for the infection control current.

Abstract: An implantable heart stimulator, comprises a pulse generator for delivering electric stimulation pulses to a patient's heart (21) through a lead (14) connectable to said pulse generator, possibly through a connector top (12) on a of pulse generator housing (10). The pulse generator housing is electrically conductive. IN an infection control apparatus for such a heart stimulator the exterior surfaces of the possible connector top and of a proximal part (16) of the lead are electrically conductive. The proximal lead part extends to a position, which after implantation of the lead is situated between a location beyond the entry to the venous system and the entry into vena cava superior.

Abstract: A heart monitoring device has a control circuit that derives an impedance value indicative of the impedance between different electrode surfaces. The control circuit determines and monitors a negative rate of change of the impedance value and determines whether the negative rate of change, or its absolute value, increases or decreases over a number of heart cycles. Alternatively or additionally, the control circuit may determine and monitor a relationship between a positive rate of change and a negative rate of change of the impedance value. The device can, in particular, be used to detect and treat a diastolic dysfunction of a heart.

Abstract: In a cardiac stimulating device and method for biventricular stimulation, the V-V interval between the stimulation pulses to the right and left ventricles is variable, and a farfield ECG obtained from measuring electrodes located outside of the heart is used for monitoring the mechanical synchronization between the right and left ventricles. The mechanical synchronization is optimized by an automatic adjustment of the V-V interval until the ORS duration is minimized.

Abstract: A heart monitoring device has a control circuit, the control circuit being adapted to be electrically connected to electrode surfaces arranged at two different positions of the heart. The control circuit derives an impedance value indicative of the impedance between the electrode surfaces. Furthermore, the control circuit is arranged to determine and monitor a relationship between a positive rate of change and a negative rate of change of the impedance value. The device can, in particular, be used to detect and treat a systolic dysfunction of a heart.

Abstract: A method of detecting the status of the battery of an implantable heart stimulator comprises the steps of measuring the impedance of the battery, detecting an increased value of the measured impedance, determining an impedance based value of the remaining capacity of the battery from the detected impedance increase, combined with the steps of measuring the total charge depleted from the battery, and determining a charge depletion based value of the remaining capacity of the battery. A battery status detecting circuit for an implantable heart stimulator includes a first measurement means (12) for measuring the impedance of the battery (6), a detection means (14) for detecting an increased value of the measured impedance, a first determination means (16) for determining an impedance based value of the remaining capacity of the battery from the detected impedance increase.

Abstract: Implantable heart stimulator comprising a pulse generating means 4 for generating stimulation pulses adapted to be applied to a heart via at least one electrode lead 6, a control means 8 with threshold search means 10 for initiating a stimulation threshold search in order to determine a stimulation threshold of heart tissue. The control means further comprises threshold search timing means 12 that generates a timing signal at same time(s) every day in order to initiate threshold searches provided that a stable condition index fulfils predetermined criteria. The stable condition index is related to the condition of the heart and is based on result from at least one heart stability test.

Abstract: Implantable heart stimulator (2) comprising a control and detection means (4), a pulse generator (6) adapted to generate stimulation pulses to a heart via at least one electrode lead (8) adapted to be inserted into the heart of a patient The electrode lead is provided with an electrode surface (10) intended to be in contact with heart tissue. A microinstability test is performed by the control means during a predetermined number of stimulation pulses, e.g. 15, where all pulses during the test have the same stimulation energy, and a microinstability test value is determined, wherein said value is a measure of the contact between the electrode surface and heart tissue.

Abstract: An implantable lead for an implantable active device, such as a pacemaker, has at least two electrodes, and a proximal end adapted for electrical and mechanical connection to the active device and a distal end opposite the proximal end. A ventricular electrode is carried at the distal end of the lead for sensing and/or electrical interaction with the ventricle, and an atrial electrode is carried on the lead for sensing and/or electrical interaction with the atrium, the atrial electrode being disposed between the proximal end and the ventricular electrode. The lead at its distal end has a first part with a first predetermined length, which is between 9 and 13 cm, and which exhibits a first stiffness. Adjacent to this first part is a second part, having a second predetermined length, which exceeds 15 cm, and which exhibits a second stiffness.

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: 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: A heart stimulating device for avoiding problems related to fusion beats contains a pulse generator for delivering stimulation pulses to a patient's heart and having a basic escape interval, a detector with a filter which senses QRS characteristics in IEGM signals, a logic stage which controls the pulse generator, and a detector without a filter which senses QRS characteristics in IEGM signals. The logic stage activates the detector without a filter preceding an end of the basic escape interval and prolongs the basic escape interval by a predetermined extension interval if the detector without a filter senses a QRS indication.

Abstract: An implantable heart defibrillator includes a pulse generator controlled by a control unit for emitting defibrillation pulses. The pulse generator is controllable to emit a number of low-energy defibrillation pulses, having a lower pulse amplitude and a shorter pulse duration than a conventional defibrillation pulse, with the total energy in the number of low-energy defibrillation pulses being less than the energy in a conventional defibrillation pulse. Each pulse in the number of low-energy defibrillation pulses, however, contains enough energy to depolarize heart cells oriented favorably in relation to the direction of the electrical field of the low-energy defibrillation pulse.

Abstract: A temporarily implantable electrode device, intended for sensing electrical signals from living tissue, has an insulating sheath of resorbable material, and at least one non-toxic, liquid conductor contained inside the insulating sheath in order to form an electrical conductor which, via an electrode adapted for interaction with living tissue can sense and carry electrical signals from living tissue to a medical apparatus connected to the electrode device. The resorbable material ultimately dissolves completely into the body of the subject in whom the electrode device was temporarily implanted, and the non-toxic, liquid conductor simultaneously mixes with other fluids, making explantation of the electrode device unnecessary.

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: In order to be able to set the distribution of current of the defibrillation current across the heart muscle, a defibrillator/cardioverter has n (n.gtoreq.3) electrodes connected to a pulse generator having n-1 outputs with a total of n output terminals to which the electrodes are connected. A measuring unit generates a measured signal dependent on the geometrical arrangement of the electrodes with reference to the heart. This measured signal is utilized for setting the pulse heights of the defibrillation pulses to be simultaneously generated at the outputs.