Abstract: In a compression and decompression coding method, arrangement and computer program product, a data signal containing a number of symbols is converted into a series of codewords. A set of codewords is established and the data signal is monitored to determine the most frequently occurring symbols therein and/or sequences of symbols therein containing at least two symbols. A codeword is then allocated to each of the most frequently occurring of the symbols and/or symbol sequences. At least one codeword is reserved for indicating uncompressed data. When compressing a signal, the incoming symbols are first checked to determine if they correspond to a codeword. If a symbol corresponds to more than one codeword, further symbols are read until a symbol occurs which corresponds to one codeword only. That codeword is then transmitted. Any symbol that does not correspond to a codeword is supplemented with a codeword indicative of no compression and is then transmitted.

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 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: In an apparatus for determining the actual status of a piezoelectric sensor in a medical implant, electrical charges generated in the sensor, in response to changes in acceleration and/or gravitational force or other loads acting on the sensor, are continuously detected and the charges are then removed from the sensor, thereby maintaining the voltage across the sensor at a substantial constant zero level. The detected charges, both negative and positive, are integrated, thereby providing a resulting integrated signal representing the actual status of the sensor. The integrated signal is then evaluated for determining the physical activity and/or the posture of a patient in whom the medical implant is implanted.

Abstract: The invention relates to a fluid pressure sensor for a lead (18) or catheter preferably intended to be placed in a living organism, such as the heart of a human being, said sensor comprising a piezoelectric element (4, 10, 11, 14) delivering an electric signal when subjected to a pressure variation, said piezoelectric element (4, 10, 11, 14) being designed to exhibit circumferential sensitivity and being disposed on at least parts of the outer surface of a rigid annular or tubular supporting structure (2). The rigidity of said sensor is such that the signal from the sensor relating to the pressure transferred to the sensor through an ongrowth of for instance tissue on the sensor would be at least 90% of the signal from the sensor without the ongrowth.

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: A medical implant has an element with at least a part thereof which is composed of piezoelectric material. The piezoelectric material is suitable for contact with body tissue and/or body fluids, and has the formula NaxKyNbO3, with 0≦x≦0.8, 0.2≦y≦1, and x+y=1.

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 biocompatible medical implant has at least one part thereof composed of ceramic material with the formula NaxKyNbO3, wherein 0≦x≦0.8, 0.2≦y≦1, and x+y=1. The ceramic material can be polarized to give the implant spatially varying piezoelectric properties. Signals can be measured from the respective piezoelectric regions of the selectively polarized ceramic material to provide an indication of the degree of fixation of the implant to surrounding tissue.

Abstract: A system for individually adapted interactive training, knowledge maintenance and for offering knowledge support, said system including an apparatus (1) comprising means representing a software-based service, said apparatus being arranged in a communications network (2), to which network a user can connect by means of a user terminal (3) in order to utilise said service. A subject database (4), adapted for storage of data relating to said service, can be connected to said apparatus. Said apparatus comprises a processing means (5) functioning to process and convey data from the subject database to the user, whereby a registration means (6) is provided, functioning to register transactions performed by the user within said service, and to store transaction data in a knowledge database (7) comprised in the apparatus. Said processing means is, according to the invention, arranged to adapt said service to said user in dependence of transactions stored in said knowledge database.

Abstract: In the determination of an optimal rate for the delivery of stimulation pulses to a heart, the stroke volume (SV) of a heart ventricle is measured as a function of heart rate (HR), e.g. by determination of impedance in individual heart cycles whose duration is varied from the duration corresponding to the prevailing rate or the basic rate regarded as optimal for stimulation. The optimal rate should lie at the knee of this function. A corresponding knee is also found in the curve for cardiac output (CO). This rate is determined by calculation of an auxiliary function, e.g. HF=HR.times.CO, which displays a peak at the heart rate at which the knee is located, and the heart rate is determined which yields this maximum. The heart rate determined in this manner is subsequently employed as a basic rate.

Abstract: A device for determining the respiration rate and/or respiration depth of a patient includes a sensor for sensing heart sounds and an analyzer for analyzing the variation of the amplitude of the sensed heart sounds to determine the respiration rate and/or respiration depth from this amplitude variation. An apparatus for monitoring the respiration of a patient includes such a device and the analyzer is arranged to determine an anomaly in the amplitude variation of the sensed heart sounds as an indication of a respiration anomaly.

Abstract: In a system for detecting changes in body posture, electrocardiograms are recorded. The recorded electrocardiograms analyzed are to determine changes in the body posture of a patient from changes in the morphology of the recorded electrocardiograms. The electrocardiogram analysis can be augmented by obtaining and analyzing an accelerometer signal as well.

Abstract: In a magnetic field detector as well as in a combined telemetry and magnetic field detector unit in a medical implant, a magnetic field sensor with a coil and a diode are employed for determining the presence of a magnetic field. For making such a determination, the coil is charged by a source of voltage for a defined period of time, the time for the discharge of the coil through the diode depending on whether a magnetic field is present. A detection signal indicating the presence of a magnetic field is generated if the discharge time is less than a defined time threshold value.

Abstract: In a magnetic field detector as well as in a combined telemetry and magnetic field detector unit in a medical implant, a magnetic field sensor with a coil and a diode are employed for determining the presence of a magnetic field. For making such a determination, the coil is charged by a source of voltage for a defined period of time, the time for the discharge of the coil through the diode depending on whether a magnetic field is present. A detection signal indicating the presence of a magnetic field is generated if the discharge time is less than a defined time threshold value.