Abstract: A multi-chamber pacing system has a pulse generator for successively delivering pacing pulses to chambers of a patient's heart, and IEGM signal detectors, having blanking intervals following the delivery of pacing pulses, including sensing circuits for sensing IEGM-signals from each of the heart chambers. Each of said sensed IEGM signals has a generally known morphology. A signal-reconstructing unit reconstructs the IEGM signal from one of the heart chambers in the blanking interval following delivery of a pacing pulse to another heart chamber.

Abstract: A pacemaker has a pulse generator for delivering stimulation pulses to a patient's heart, a sensor for measuring a parameter related to cardiac output, and a control unit for controlling the delivery of stimulation pulses from the pulse generator. The control unit includes an altering unit for altering at least one of the VV delay between consecutive stimulation pulses to the right and left ventricles and the AA delay between consecutive stimulation pulses to the right and left atria. The sensor measures the parameter in various time windows within a time of operation of predetermined VV- or AA-delay values. A determining unit includes a calculation unit for calculating an average value of the measured parameter during each of said time windows and the determining unit uses these average values to determine which one of the VV- and/or AA-delay values results in a higher cardiac output.

Abstract: An implantable bi-ventricular heart stimulating device has a control circuit that within a time cycle, delivers pacing pulses with both first and second pacing circuits with a time gap between a pacing pulse delivered by these pacing circuits. The time gap can be such that a pacing pulse delivered by the second pacing circuits falls substantially within a first time interval in which an evoked response can be expected to a pacing pulse delivered by the first pacing circuit. The control circuit performs a temporary modification of the operation of the device such that during at least one time cycle no pacing pulse is delivered by the second pacing circuit during the first time interval.

Abstract: A cardiac pacemaker has a pulse generator for delivering stimulation pulses to a patient's heart and a control unit for controlling the delivery of the stimulation pulses from the pulse generator. The control unit includes an altering unit for altering the AV-delay value from a predetermined first AV-delay value to a predetermined second AV-delay value, and back to the first AV-delay value. A sensor measures a parameter related to cardiac output of the patient, the sensor measuring this parameter in a time window within a time of operation with the first AV-delay value, and in a time window within the time of operation with said second AV-delay value, and in a time window within the time of operation after the return back to the first AV-delay value. A calculation unit calculates respective average values of the parameter during each of the time windows, and a determining unit determines from these average values which of the AV-delay values results in a higher cardiac output.

Abstract: In an implantable heart stimulating device, system and method, a control circuit has first and second circuits for sensing and pacing. The first circuit can be connected to a first electrode member suited to be positioned in or at a first ventricle of the heart. The second circuit can be connected to a second electrode member suited to be positioned in or at a second ventricle of the heart. The control circuit is able to detect whether signals sensed by the second circuit are likely to be far field signals. The control circuit performs this detection by at least determining whether, during a predetermined time (length, more signals are sensed by the second circuit than by the first circuit.

Abstract: An evoked response detector for a biventricular pacing system has a measuring arrangement for measuring a cardiac parameter signal indicative of mechanical contraction of the heart after a biventricular stimulation. A comparator compares the parameter signal, in a time window of predetermined length after the stimulation, with a number of predetermined stored parameter signal templates representing different capture situations to determine most similar template and thus the existing capture situation.

Abstract: An implantable bi-ventricular heart stimulating device (10) has a control circuit with first and second sensing circuits for respectively sensing in the two ventricles and first and second stimulation circuits for respectively stimulating the two ventricles. The control circuit determines whether a signal, sensed by said second sensing circuit, occurs essentially simultaneously with a signal sensed by the first sensing circuit. Furthermore, the control circuit determines whether a further signal is sensed by said second sensing circuit within a predetermined time interval which follows after the signal sensed by the second sensing circuit but within the same time cycle as that signal. If this occurs, the control circuit determines whether the sensed signals represent actual cardiac events, or are likely the result of far field detection.

Abstract: An implantable bi-ventricular heart stimulating device and system operate, within a time cycle, to deliver pacing pulses with both a first and a second pacing circuit with a first time delay between these pacing pulses. The device employs a criterion with which a signal typical for a premature ventricular contraction is detected. The device also operates with a second time delay and/or with a third time delay, and, if a predefined pacing rule is fulfilled, to deliver a pacing pulse with the second time delay or said third time delay. The risk for arrhythmia in connection with a PVC is reduced.

Abstract: A multi-chamber pacing system has a pulse generator for successively delivering pacing pulses to chambers of a patient's heart. Evoked response detectors having blanking intervals following the delivery of pacing pulses include sensing elements for sensing IEGM-signals from each of the heart chambers and an integrating unit that integrates the IEGM-signal within evoked response detection time windows after delivery of pacing pulses for detecting evoked response. The evoked response detection time window for a heart chamber contain at least one blanking interval resulting from delivery of a pacing pulse to another chamber and each of the sensed IEGM signals having a generally known morphology. An integral reconstructing unit reconstructs the time integral of the IEGM signal from one of the heart chambers in the blanking interval following delivery of a pacing pulse to another heart chamber.

Abstract: A multi-chamber pacing system has a pulse generator for successively delivering pacing pulses to chambers of a patient's heart, and IEGM signal detectors, having blanking intervals following the delivery of pacing pulses, including sensing circuits for sensing IEGM-signals from each of the heart chambers. Each of said sensed IEGM signals has a generally known morphology. A signal-reconstructing unit reconstructs the IEGM signal from one of the heart chambers in the blanking interval following delivery of a pacing pulse to another heart chamber.

Abstract: An implantable bi-ventricular heart stimulating device and system, suitable for treating congestive heart failure, have a control circuit with first and second pacing circuits and first and second sensing circuits. The device operates with time cycles corresponding to normal heart cycles. The control circuit determines: (a) whether a signal typical of an evoked response to a pacing pulse delivered by the first pacing circuit is sensed within a first time interval and (b) whether a signal typical for an R-wave transferred from the second ventricle, or from some other part of the heart, to the first ventricle is detected within a first time window. The operation of the device depends on whether the conditions (a) and (b) are fulfilled.

Abstract: In a method and an apparatus for verifying the occurrence of an evoked response in the atrium, following emission of a stimulation pulse to the atrium, an impedance signal is measured in a time window following the emission of the stimulation pulse. The impedance signal is high pass filtered and a characteristic of the high pass filtered impedance signal, such as its amplitude or its morphology, is compared to a predetermined criterion in a comparison unit. The occurrence of an evoked response is verified if the characteristic equals or exceeds the predetermined criterion. The occurrence of an evoked response can therefore be monitored on a beat-to-beat or pulse-to-pulse basis.

Abstract: An implantable bi-ventricular heart stimulating device has a control circuit that within a time cycle, delivers pacing pulses with both first and second pacing circuits with a time gap between a pacing pulse delivered by these pacing circuits. The time gap can be such that a pacing pulse delivered by the second pacing circuits falls substantially within a first time interval in which an evoked response can be expected to a pacing pulse delivered by the first pacing circuit. The control circuit performs a temporary modification of the operation of the device such that during at least one time cycle no pacing pulse is delivered by the second pacing circuit during the first time interval.

Abstract: In an implantable heart-monitoring device and system, and a heart-monitoring method, a control circuit is connected to one or more sensors, a first of which is positionable in the coronary sinus region of a heart and senses at least one blood constituent, and at least one other of the sensors supplying a signal to the control circuit indicative of the activity of the heart. In response to signals from the first sensor and with information about the activity of the heart from the other sensor, the control circuit determines a first value of the blood constituent during a first portion of a heart cycle, and determines a second value of the blood constituent during a second portion of the heart cycle.

Abstract: A heart stimulator for electric stimulation of a patient's heart has an impedance measuring unit that measures the impedance between at least two measurement electrodes implanted in a patient such that volume changes of at least one of the chambers of the left heart result in changes in the measured impedance. An analyzer analyzes the measured impedance for the control of the stimulation of the heart. A calculation unit calculates an average impedance morphology curve during a time interval of several cardiac cycles. The analyzer analyzes the average impedance morphology curve for use for the control of the stimulation to optimize the patient hemodynamics.

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 pacemaker has a stimulation threshold measuring unit which measures a stimulation threshold voltage value of a heart and a pulse generator for deliverying stimulation pulses of variable amplitudes and durations to the heart. The pulse generator is controlled by a control unit to deliver the stimulation pulses with respective amplitudes related to the measured threshold value and a safety margin. The control unit automatically changes the safety margin in accordance with a predetermined relationship between the safety margin and the measured threshold value, so that the safety margin is progressively increased as the measured threshold value increases.

Abstract: A pacemaker has a pulse generator for delivering stimulation pulses to a patient's heart and a control unit for controlling the delivery of stimulation pulses from the pulse generating means. A sensor is provided to measure a parameter related to cardiac output of the patient. The control unit includes an altering unit for altering at least one of the VV-delay between consecutive stimulation pulses to the right and left ventricles and the AA-delay between consecutive stimulation pulses to the right and left atria, from a predetermined first VV- or AA-delay value to a predetermined second VV- or AA-delay value, and back to the first VV- or AA-delay value. The sensor measures the parameter in a time window within a time of operation with the predetermined first VV- or AA-delay value, in a time window within a time of operation with the predetermined second VV- or AA-delay value and in a time window within a time of operation after the return back to the first VV- or AA-delay value.