Abstract: An implantable cardiac stimulating device has an atrial pulse generator and an atrial sensor connected to an atrial electrode, for delivering stimulating pulses to the atrium and sensing events in the atrium. The stimulating device also has a ventricular pulse generator and a ventricular sensor connected to a ventricular electrode for delivering stimulating pulses to the ventricle and for sensing events in the ventricle. The ventricular sensor also includes an evoked response detector. A control unit causes the ventricular pulse generator to deliver a back-up pulse if no evoked response is detected. The control unit operates the atrial pulse generator in a first manner wherein no stimulating pulse is delivered to the atrium and in a second manner wherein stimulating pulses are delivered to the 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: An electrode lead for a medical implant, such as a pacemaker, has a proximal end for connection to the implant and a distal end opposite thereto having an electrode and fixation structure for holding the distal end in place relative to surrounding tissue. A distal end part at the distal end has a tape ring shape, in the form of a truncated cone, and the fixation structure forms a helical thread around the distal end part. The height of the thread is such that the crest of the thread is located within an imaginary, second truncated cone that is coaxial with the distal end part. The crest of the thread is located within an imaginary cylinder that is coaxial with the cylindrical lead body and which has the same diameter as the lead body, this imaginary cylinder intersecting the imaginary, second truncated cone.

Abstract: In a method and circuit for monitoring an oscillator in a medical implant, a physiological parameter is obtained from a subject in whom the medical implant is implanted and an electric signal containing a time component, is generated based on the physiological parameter. The functioning of the oscillator is monitored using this electric signal to identify if the functioning of the oscillator deviates from a specified functioning of the oscillator.

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: A pacemaker has a metallic housing with a connector arrangement adapted to receive a contact plug, with contact surfaces, at the proximal end of an electrode lead. The connector arrangement includes a metallic tubular member with opposite ends which are welded or bonded to respective openings in the metallic housing. The metallic tubular member is substantially continuous along its length between the opposite ends. All components which are needed for making electrical contact with the contact surfaces of the lead are contained within the interior of the metallic tubular member.

Abstract: A housing for an implantable tissue stimulating device is connectable to an electrode lead having an electrode. A portion of the housing also functions as an electrode. The walls of the housing are shaped so that when a voltage is applied between the electrode at the electrode lead, and the housing electrode, the electric field associated with the voltage has a low field strength in regions at which unwanted stimulation of muscles can occur.

Abstract: A cardiac pacemaker has a pulse generator which emits stimulation pulses which are respectively separated by stimulation intervals and which collectively have an average duration. A modulation device alternatingly shortens and lengthens the stimulation intervals, without changing the average duration. An evaluation unit analyzes signals detected after each stimulation pulse and determines the electric restitution of the heart at the average stimulation interval duration on the basis of a measurement of the duration of the action potential. Changes in a measuring variable, associated with the duration of the action potential, caused by the modulation of the stimulation intervals is determined in a relationship to the average duration of the stimulation interval. This relationship is compared with at least one predetermined value, and the average duration of the stimulation interval is controlled on the basis of this comparison.

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 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: 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: The invention relates to a locking device (1) for a female connector part for cooperation with an elongate, male connector part (30), said female connector part being intended for use in a pacer housing. Said female connector part comprises a longitudinal bore defining a longitudinal space for said locking device. Said locking device comprises one or several tongues (19, 19?) being swingable between two positions, a first position in which the tips of the tongues (19, 19?) can engage said male elongate connector part (30) and a second position in which the tips of the tongues (19, 19?) will not engage the male elongate connector part (30). Said tongues are biased towards said first position by means of a spring force. A pivot (9) is associated with each tongue and each tongue has a first part engaging said connector means (30) and being located on one side of said pivot and a second part being located on the other side of said pivot.

Abstract: A fluid pressure sensor for a lead or catheter intended for placement in a living organism, such as a human heart, includes a rigid annular or tubular supporting structure and a piezoelectric element disposed on at least a portion of the outer surface thereof. The piezoelectric element delivers an electrical signal when subjected to a pressure variation, and exhibits circumferential sensitivity. The rigidity of the sensor is defined to satisfy predetermined criteria to ensure that the sensor, when sensing pressure transferred to the sensor through an on-growth of tissue on the sensor, which is at least 90% of the signal which the sensor would emit without the on-growth.

Abstract: A rate adaptive pacemaker has a measuring unit which interacts with a patient to determine a demand, a pacing rate controller connected to the measuring unit for controlling the pacing rate in response to the demand, and a pacing rate limiter connected to the pacing rate controller which upwardly limits the pacing rate so as to always maintain the energy supplied to the myocardium at a level which exceeds the energy consumed by the myocardium.

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: A pacemaker is operable in a tracking and a non-tracking mode and has an automatic mode switching function for switching the pacemaker into the non-tracking mode of operation in response to the detection of atrial tachycardia. A comparator compares an atrial interval, between detected atrial events, with a predetermined atrial tachycardia limit value and records a tachycardia indication if the interval is less than the atrial tachycardia limit value. The mode switching unit switches the mode of operation to the non-tracking mode if the number of recorded tachycardia indications reaches a predetermined tachycardia count limit. Intervals between other cardiac events detected by the atrial detector or a ventricular detector also are supplied to the comparator wherein they are compared with the atrial tachycardia limit value.

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: 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: A heart stimulator has a pulse generator which emits stimulation pulses for delivery to the heart of a patient through a lead connected to the pulse generator and introduced into the heart. The heart stimulator has an evoked response detector which includes a measuring unit for measuring electrode signals picked up by the lead. An averaging unit is supplied with the electrode signals and forms an average value of the amplitude of the respective electrode signals for each heartbeat. A comparator in the evoked response detector compares the average value for each heartbeat with two predetermined limit values and emits a signal indicating that the electrode signal results from a fusion beat if the average values are between the two limit values.

Abstract: An implantable heart stimulating device with atrial overdrive capability has an atrial stimulation unit for stimulating the atrium via stimulation electrode(s), an atrial evoked response detector adapted to determine an atrial evoked response amplitude, and an atrial control unit to control an atrial timing unit to set an atrial stimulation time interval length between consecutively applied atrial stimulation pulses. The atrial stimulation time interval length is set in dependent on the determined atrial evoked response amplitude such that the next time interval length is a predetermined percentage of the present time interval length. If the ER signal amplitude decreases, the stimulating interval has to be decreased. The pacemaker can also try to increase the stimulating interval back to back until a decrease in ER signal amplitude is seen in order to avoid too high stimulating rate.