Abstract: An implantable cardiac stimulation device has an atrial detector that detects atrial events of a patient's heart, and a memory in which sequences of IEGM signals are stored, having a predetermined length, and an analyzing unit that analyzes the sequences to determine if the stored sequences contain atrial events having a lower amplitude than the current sensitivity setting of the atrial detector. A control unit is connected to the atrial detector to adjust the sensitivity setting thereof to a threshold that is determined based on the aforementioned analysis of the IEGM signals.

Abstract: In a method and an arrangement for evaluating operational effectiveness of an implantable medical device for different lead placements associated with the medical device, a measuring unit records signals that are characteristic of cardiac activity at respectively different lead positions, and these signals are stored. A processor accesses the stored signals and, from the stored signals, determines a measure of cardiac activity at each of the lead positions. The recorded signals may be intracardiac ECG signals, surface ECG signals, heart sound signals obtained from a microphone, or impedance signals. The lead position at which the best hemodynamic behavior of the heart is identified from the analysis of the stored signals, and is determined as being the optimum site for placement of the electrode leads.

Abstract: In an electrically conductive lead adapted for implantation in a human or animal body, and a method for making such a lead, a drug-dispensing member is disposed at a distal end portion of the lead, at which an electrode member is disposed that is adapted to emit and/or sense electrical signals associated with medical therapy. The drug-dispensing member has a configuration so that, after implantation, the amount of drug released into the body per time unit is automatically controlled to smoothly vary with time from al larger amount to a smaller amount in accordance with a predetermined relationship of the amount of drug released as a function of time.

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: 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 has a pulse generator, implantable in a subcutaneous pocket, and an electrode lead connected thereto for delivering stimulation pulses to a patient's heart. The pulse generator has an electrically conductive housing, and the electrode lead has a proximal portion which after implantation, extends substantially from the housing to a location situated beyond entry into the venous system and before entry into the superior vena cava. The proximal portion has an exterior with an electrically conductive surface, which together with the housing, form an infection control current electrode. A counter electrode is disposed outside of the subcutaneous pocket, and a current source supplies an infection control current between the infection control current electrode and the counter electrode for counteracting bacterial growth at least on an exterior of the housing.

Abstract: In a cardiac stimulating device for biventricular stimulation, an intracorporeal ECG signal obtained from measuring electrode leads located outside of the heart is used for monitoring capture of the right and left ventricles. If loss of capture is detected in any of the ventricles then the pacing pulse energy will be adjusted to obtain complete biventricular capture.

Abstract: In a cardiac stimulating device, an infection control current is generated and applied to a subject in whom a medical device is implanted by completing a circuit including an entirely electrically conductive exterior of a housing of the device, an electrode carried by an electrode lead of the device, and an electrically conductive surface of a proximal portion of the electrode lead, extending from the housing to a location, after implantation, situated beyond entry of the electrode lead into the venous system and before entry of the electrode lead into the superior vena cava. The infection control current can be a current with a square waveform, and the circuit can be completed at selected times, such as only during the refractory period of the subject's heart.

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 congestive heart failure monitor has an impedance measuring unit that measures the impedance between at least two electrodes implanted in a patient, to use a detected change of the measured impedance as an indication of a change in the left atrium volume. Any analyzing unit analyzes the measured impedance and detects insipient congestive heart failure dependent on a quotient of a maximum value of the measured impedance and a minimum value of the measured impedance during a cardiac cycle.

Abstract: In a method and apparatus for determining the depleted capacity of a CFx type battery used in an implantable medical device, average values of battery voltage and battery current drawn from the battery are measured during a measurement time, the length of which exceeds a battery voltage recovery time after a load change, and wherein the actual depleted capacity of the battery is determined by predetermined relations between combinations of the average values of voltage and current and depleted battery capacity.

Abstract: A heart stimulator has an atrial and ventricular pulse generator for producing atrial and ventricular stimulation pulses, an atrial sensor for sensing atrial signals and an evoked response detector for detecting the occurrence of incipient fusion beats from measured ventricular signals. A determination unit determines an incipient fusion AV-interval from the sensed atrial signals and the detected fusion beats, and a controller controls the pulse generator to deliver stimulation pulses at a controlled AV-interval which is shorter than the incipient fusion AV-interval.

Abstract: An implantable heart stimulator has a heart signal detector adapted to detect electrical heart signals and to apply the detected signals to at least two detection channels. Each detection channel includes a filter, with each filter having a passband that differs from the passband of the other filters. Each channel also includes a threshold detector and a peak amplitude determining unit connected to the output of the filter in that channel. A heart event identifying unit is connected to the outputs of each channel and unambiguously identifies a type of signal which produced a detected heart event by applying predetermined identifying criteria to the outputs of the threshold detector and the peak amplitude determining unit from each channel.

Abstract: The invention relates to an implantable dual chamber heart stimulator comprising a stimulation threshold detector arranged to activate a stimulation threshold search algorithm to perform a stimulation threshold search at predetermined time intervals in order to determine a stimulation threshold of heart tissue. The heart stimulator comprises an AV-interval generator adapted to generate an AV-interval and a controller arranged to temporarily shorten the AV-interval to a threshold search AV-interval when this threshold search is performed. The heart stimulator further comprises AR/PR-interval measure adapted to measure the actual AR/PR conduction time in which this threshold search AV-interval is set by the AV-interval generator and the controller to the measured AR/PR-interval shortened by a predetermined time.

Abstract: An implantable cardiac stimulating device has a control circuit which varies the rate of stimulation pulses up to a maximum pacing rate. A sensor senses at least one evoked response parameter to a delivered stimulation pulse, and the control circuit compares a time gap between the stimulation pulse and its associated evoked response parameter. The control circuit lowers the maximum pacing rate if the time gap does not increase as the pulse rate is increased.

Abstract: An implantable heart stimulator has an AV-interval generator which generates a variable AV-interval and which is provided with a predetermined basic AV-interval. The heart stimulator has a counter that counts the number of times the AV-interval is changed in response to a fusion avoidance algorithm or a stimulation threshold search algorithm during a predetermined time period. The basic AV-interval is changed if the number of times counted by the counter is greater than a predetermined value.

Abstract: An implantable cardiac stimulating device has a control circuit connected to first and second electrodes respectively for stimulating first and second ventricles of a heart. Evoked response sensors respectively sense evoked response parameters to stimulation of the two ventricles. Delivery of stimulating pulses via the respective electrodes to the respective ventricles in the same cycle of the heart is controlled so that there is a time interval between the pulses respectively delivered to the two ventricles. The control circuit controls delivery of the stimulating pulses so that the respective evoked response parameters of the two ventricles occur substantially simultaneously.

Abstract: An implantable heart stimulator has a control and detection circuit which operates a pulse generator which emits stimulation pulses which are delivered to cardiac tissue via at least one electrode lead adapted for insertion in the heart of a patient. The electrode lead has an electrode surface which is intended to be in contact with heart tissue. The control and detection circuit performs a microinstability test by causing the pulse generator to emit a predetermined number of stimulation pulses, each having the same stimulation energy. The control and detection circuit determines a microinstability test value, representing a measure of the contact between the electrode surface and the heart tissue, as a ratio of a number of stimulation pulses, within said predetermined number of stimulation pulses, for which capture is detected, and the predetermined number of stimulation pulses.

Abstract: In an electrically conductive lead adapted for implantation in a human or animal body, and a method for making such a lead, a drug-dispensing member is disposed at a distal end portion of the lead, at which an electrode member is disposed that is adapted to emit and/or sense electrical signals associated with medical therapy. The drug-dispensing member has a configuration so that, after implantation, the amount of drug released into the body per time unit is automatically controlled to smoothly vary with time from al larger amount to a smaller amount in accordance with a predetermined relationship of the amount of drug released as a function of time.

Abstract: In a cardiac stimulating device for biventricular stimulation, an intracorporeal ECG signal obtained from measuring electrode leads located outside of the heart is used for monitoring capture of the right and left ventricles. If loss of capture is detected in any of the ventricles then the pacing pulse energy will be adjusted to obtain complete biventricular capture.