Abstract: An implantable medical device has a pressure sensing arrangement to measure right ventricular pressure of a heart including a pressure sensor adapted to be positioned in the right ventricle of the heart, to measure the pressure and to generate a pressure signal in response to the measured pressure. The pressure sensing arrangement also has a pressure signal processor and a timing unit. The processor determines from the pressure signal, using diastolic timing signals from the timing unit based on the pressure signal identifying the diastolic phase, a diastolic pressure signal representing the ventricular pressure only during the diastolic phase of the heart cycle.

Abstract: In an implantable intravascular pressure determining device and method, a pressure sensor generates a raw pressure signal and an acceleration sensor measures acceleration in a patient. Time intervals are identified wherein the raw pressure signal accurately represents the intravascular pressure, these intervals being identified as the time intervals wherein the measured acceleration is below a predetermined threshold. The raw pressure signal is processed, to generate a processed signal which is used as an intravascular pressure signal, only in the aforementioned time intervals.

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: A method that determines if a sender's message is to be sent to a recipient is presented. A challenge module analyzes the message and sends a challenge message to the sender if the sender is not in the recipient's address store. The challenge message includes a pseudo unique token for the sender recipient pair such that the sender must respond differently to each challenge message for a particular message. In one embodiment, the challenge message requires the sender to obtain a certificate from a certificate authority or a set of authorities.

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: 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 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: 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: A cardiac lead has an end adapted for contact with cardiac tissue that has a number of dot-like electrodes which are separated from each other by electrically insulating material, and which are positioned at respective locations adapted for simultaneous contact with the cardiac tissue. The dot-like electrodes produce respective unipolar signals. At least one difference signal from the unipolar signals of a pair of the dot-like electrodes. The difference signal is edited in circuitry of a cardiac assist device and is compared to a threshold. If the threshold is exceeded, a signal indicating a cardiac rhythm abnormality, such as fibrillation, is generated for triggering electrical therapy delivered to the cardiac tissue by the cardiac assist device.

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: An implantable cardiac stimulation device operates according to a first pacing algorithm executable by a microprocessor and which is able to independently perform stimulation therapy for a patient's heart, as well as according to a second pacing algorithm which is also microprocessor-executable. The first and second algorithms actively generate stimulation parameters during each cardiac cycle, but the stimulation parameters generated by the second algorithm are only permitted to result in actual stimulation therapy if those parameters fall within parameter ranges that are calculated to be allowable for stimulation by the first algorithm.

Abstract: In an implantable intravascular pressure determining device and method, a pressure sensor generates a raw pressure signal, an acceleration sensor generates an acceleration signal, and an evaluation unit determines a disturbance pressure signal from the acceleration signal. A processed signal is generated as the difference between the raw pressure signal and the disturbance pressure signal. The processed signal corresponds to intravascular pressure.

Abstract: A cardiac lead has an end adapted for contact with cardiac tissue that has a number of dot-like electrodes which are separated from each other by electrically insulating material, and which are positioned at respective locations adapted for simultaneous contact with the cardiac tissue. The dot-like electrodes produce respective unipolar signals. At least one difference signal from the unipolar signals of a pair of the dot-like electrodes. The difference signal is edited in circuitry of a cardiac assist device and is compared to a threshold. If the threshold is exceeded, a signal indicating a cardiac rhythm abnormality, such as fibrillation, is generated for triggering electrical therapy delivered to the cardiac tissue by the cardiac assist device.

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 an implantable intravascular pressure determining device and method, a pressure sensor generates a raw pressure signal, an acceleration sensor generates an acceleration signal, and an evaluation unit determines a disturbance pressure signal from the acceleration signal. A processed signal is generated as the difference between the raw pressure signal and the disturbance pressure signal. The processed signal corresponds to intravascular pressure.

Abstract: In an implantable intravascular pressure determining device and method, a pressure sensor generates a raw pressure signal and an acceleration sensor measures acceleration in a patient. Time intervals are identified wherein the raw pressure signal accurately represents the intravascular pressure, these intervals being identified as the time intervals wherein the measured acceleration is below a predetermined threshold. The raw pressure signal is processed, to generate a processed signal which is used as an intravascular pressure signal, only in the aforementioned time intervals.

Abstract: In an implantable electrode for an electrode lead for a stimulation device for stimulating tissue, the electrode is formed as a biocompatible piezoelectric electrode which is adapted to be in direct electrical contact with tissue for electrically and mechanically stimulating the tissue and for detecting electrical and mechanical evoked response of the stimulated tissue. The stimulation device can include circuitry for making a diagnosis of a heart condition using signals received from the implantable electrode.

Abstract: An implantable medical device has a pressure sensing arrangement to measure right ventricular pressure of a heart including a pressure sensor adapted to be positioned in the right ventricle of the heart, to measure the pressure and to generate a pressure signal in response to the measured pressure. The pressure sensing arrangement also has a pressure signal processor and a timing unit. The processor determines from the pressure signal, using diastolic timing signals from the timing unit based on the pressure signal identifying the diastolic phase, a diastolic pressure signal representing the ventricular pressure only during the diastolic phase of the heart cycle.

Abstract: A pacemaker has control circuits contained in an enclosure and a lead containing an electrical conductor connected to an electrode for delivering electrical stimulation pulses to a heart. The stretching of a wall in the ventricle, corresponding to adequate filling of the ventricle in the heart, is determined in order to identify a time of emitting the stimulation pulses. This stretching is measured indirectly by measurement of pressure in the ventricle using a pressure sensor disposed near the lead in the ventricle. The signal from the sensor is supplied via the lead to circuitry in the enclosure, wherein the signal is amplified and is supplied to an edge detector, which detects an increasing or positive edge of the signal.