Abstract: A circuit and method for detecting cardiac rhythm abnormalities employ unipolar signals respectively obtained from a cardiac lead having a tip at which a number of separate electrodes are disposed, the electrodes being simultaneously in contact with cardiac tissue. The respective unipolar signals which are obtained from the multiple electrodes exhibit a time relationship relative to each other, and this time relationship is analyzed to determine whether a cardiac rhythm abnormality is present or one or more of the unipolar signals is compared to a template which is known to represent a cardiac abnormality. Analysis of the time relation is undertaken by determining the absolute value of a time offset between any two of the unipolar signals, or by correlating any two of the unipolar signals.

Abstract: An implantable heart monitoring and stimulating device has a control circuit and a memory, the control circuit receiving signals representing detected cardiac events respectively from the right and left ventricles of a heart. The control circuit controls a pulse generator to transmit stimulation pulses to the right and left ventricles as well. The control circuit determines the time, within a heart cycle, between a first event related to the right ventricle and a second event related to the left ventricle, or vice versa. The determined time is stored in the memory. The determination and storage of the aforementioned time are repeated at a number of occasions.

Abstract: In a method for automatic creation of a template for a morphology sensitive detector for an implantable cardiac stimulating device and a cardiac stimulating device operating according to the method, a predetermined length of the heart signal is recorded and filtered, all deflections exceeding a predetermined amplitude are identified and stored based on the condition that selected deflections must be separated at least by a predetermined amount of time, all selected deflections are categorized into separate classes, and the most representative class or classes for creation of the template is selected.

Abstract: In an implantable heart stimulating device, system and method, electrical stimulation pulses are delivered to first and second ventricles of a heart with a variable time interval therebetween, and signals are sensed at two different positions in the heart, from which an impedance value is derived. A minimum value and a maximum value of the impedance value are determined during a heart cycle, and a relationship between the minimum and maximum values also is determined. The time interval is varied and the relationship is monitored over a number of heart cycles. The time interval is set so that the relationship satisfies a predetermined requirement.

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 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: 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 a method for identifying and classifying premature atrial contractions, a cardiac lead having multiple electrodes, electrically separated from each other, at its tip is placed in contact with cardiac tissue, so that at least two of the electrodes are simultaneously in contact with the cardiac tissue. When a depolarization wave arrives at the tip, respective unipolar signals are detected from multiple electrodes in contact with the cardiac tissue, and these signals are analyzed, such as by identifying a time offset between pairs of the signals, to identify a propagation direction of the depolarization wave. Dependent on this propagation direction, the depolarization wave is classified as representing a normal sinus beat or a premature atrial contraction. By further analysis, the premature atrial contraction, if present, is classified as originating either from the right atrium or the left atrium.

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: 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: In a method for identifying and classifying premature atrial contractions, a cardiac lead having multiple electrodes, electrically separated from each other, at its tip is placed in contact with cardiac tissue, so that at least two of the electrodes are simultaneously in contact with the cardiac tissue. When a depolarization wave arrives at the tip, respective unipolar signals are detected from multiple electrodes in contact with the cardiac tissue, and these signals are analyzed, such as by identifying a time offset between pairs of the signals, to identify a propagation direction of the depolarization wave. Dependent on this propagation direction, the depolarization wave is classified as representing a normal sinus beat or a premature atrial contraction. By further analysis, the premature atrial contraction, if present, is classified as originating either from the right atrium or the left atrium.

Abstract: A circuit and method for detecting cardiac rhythm abnormalities employ unipolar signals respectively obtained from a cardiac lead having a tip at which a number of separate electrodes are disposed, the electrodes being simultaneously in contact with cardiac tissue. The respective unipolar signals which are obtained from the multiple electrodes exhibit a time relationship relative to each other, and this time relationship is analyzed to determine whether a cardiac rhythm abnormality is present or one or more of the unipolar signals is compared to a template which is known to represent a cardiac abnormality. Analysis of the time relation is undertaken by determining the absolute value of a time offset between any two of the unipolar signals, or by correlating any two of the unipolar signals.

Abstract: In a method for automatic creation of a template for a morphology sensitive detector for an implantable cardiac stimulating device and a cardiac stimulating device operating according to the method, a predetermined length of the heart signal is recorded and filtered, all deflections exceeding a predetermined amplitude are identified and stored based on the condition that selected deflections must be separated at least by a predetermined amount of time, all selected deflections are categorized into separate classes, and the most representative class or classes for creation of the template is selected.