Abstract: A heart stimulator has a pulse generator which periodically emits stimulation pulses, least one electrode connectable to the pulse generator and to the heart for transmitting said pulses to the heart and a respiration monitor for monitoring the respiration of the pacemaker user. The heart stimulator adapts the energy to be delivered in a stimulation pulse in response to the information acquired by the respiration monitor which indicates the current stage in the user's respiration cycle.

Abstract: An implantable medical apparatus includes a therapy unit which produces a medical therapy regimen which is administered by the implantable medical apparatus to a subject. The implantable medical apparatus obtains an electrical signal representing physiological activity of the subject and performs detrended fluctuation analysis on the electrical signal so as to obtain a self-similarity parameter for the electrical signal. Deviations of the self-similarity parameter from a nominal value indicate the severity of the pathology of the subject which the implanted medical apparatus is intended to treat. The self-similarity parameter can be made extracorporeally available for use by a physician to evaluate the effectiveness of a treatment program currently in place, and/or can be supplied to a control unit of the implantable medical apparatus for use in automatically adjusting the therapy regimen administered by the implantable medical apparatus.

Abstract: In a method and apparatus for automatically adjusting the threshold detection level of a detector unit for detecting physiological events, e.g. heart contractions, a cardiac signal is sensed and sampled, the samples of the cardiac signal are stored in a memory. A timer starts the sampling and stops the sampling after a predetermined time. An analysis unit analyzes the stored cardiac signal samples to generate a first set of values which represent physiological events, such as average peak signal value, the average maximum signal slope or an integrated signal value. The analysis unit calculates at least one derived parameter from the whole of the first set of values and automatically determines a new threshold detection level for the sensor as a function of this at least one derived parameter.

Abstract: An implantable heart defibrillator includes a pulse generator controlled by a control unit for emitting defibrillation pulses. The pulse generator is controllable to emit a number of low-energy defibrillation pulses, having a lower pulse amplitude and a shorter pulse duration than a conventional defibrillation pulse, with the total energy in the number of low-energy defibrillation pulses being less than the energy in a conventional defibrillation pulse. Each pulse in the number of low-energy defibrillation pulses, however, contains enough energy to depolarize heart cells oriented favorably in relation to the direction of the electrical field of the low-energy defibrillation pulse.

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: A device for detecting a state of imminent cardiac arrhythmia, relative to a normal state for a heart, in response to activity in nerve signals conveying information from the autonomic nerve system to the heart, contains a sensor body for sensing neural activity, a comparator with a threshold value forming a condition for the presence of an arrhythmia, the comparator emitting an arrhythmia-indicating output signal depending on whether neural activity meets the condition, and the sensor body being placeable in an extracardiac position for at least one of the sympathetic and vagus nerves. The sensor body directly senses activity in the nerve at that location in direct contact with the nerve. An implanted blood pressure sensing cuff also can be provided which generates signals indicative of blood pressure which can be evaluated in combination with the nerve signals for identifying the state of imminent cardiac arrhythmia.

Abstract: A device for preventing a fixation element on the distal end of an implantable lead, during introduction into a body cavity, from coming into contact with and damaging the cavity has a protective body, which completely encloses the fixation element, and which is made of a gel-forming material. After introduction and contact with body fluid and when pressure is applied to the material against body tissue, the material permits mechanical penetration of the protective body by the fixation element, whereupon the fixation element can be affixed to the body cavity.

Abstract: In a method and apparatus for stimulating and/or diagnosing the heart, a voltage is applied to the heart over at least a selected portion of the heart during an activation interval with a rise and fall, with the voltage having a first derivative with an absolute value that is less than the value of the derivative which, for a patient in question, would trigger the patient's heartbeat, and with a duration from beginning to end of each applied voltage signal of at least 30 ms.

Abstract: A method and apparatus for calculating and monitoring the impedance of an implanted pacemaker lead, and in particular to such a method and apparatus for monitoring the impedance to determine whether a lead fault, such as a lead rupture or a lead dislocation, has occurred. In order to avoid reprogramming the implanted pacemaker to deliver a pulse having known parameters in order to permit an impedance measurement to be made, the method and apparatus operate on the basis of the system formed by the pulse generator, the electrode leads and body tissue being considered to behave as an RC circuit, with the pulse generator emitting an ideal square wave pulse which then exhibits an exponential decay in the body tissue having a decay time constant associated therewith. From surface ECG measurements, the decay time constant is estimated, and since the capacitance of the pulse generator is known, the lead impedance can then be calculated.

Abstract: An apparatus for preventing an anchoring element on the distal end of an implantable medical electrical conductor from coming into contact with and damaging the wall of a body cavity during advancement of the conductor into the cavity has a sleeve element attachable to the outer surface of the distal end of the conductor to enclose the entire length of the anchoring element, and a pulling element attached to the distal end of the sleeve element. Pulling on the pulling element from the proximal end of the conductor retracts the sleeve element after introduction of the conductor has been concluded, to expose the anchoring element for active fixation to adjacent body tissue. An implantable electrode cable equipped with such an end protector.

Abstract: A device for indicating that an electrode cable is correctly connected to a medical implant for emitting electrical pulses, the implant being equipped with a connection part for the electrode cable's proximal end, has a contact for making electrical connection with the proximal end of the electrode cable and an indicator, the contact electrically causing the indicator to emit at least one indication signal which is perceptible outside of the implant when the electrode cable is correctly attached to the implant.

Abstract: A method for making an electrical contact for a vitreous carbon electrodes includes the steps of making a bore in an electrode blank of a cross-linked artificial resin forming the electrode blank into an electrode body. A solid or hollow pin, or a sleeve, composed of a biocompatible, refractory metal is introduced into the bore. If a pin is to be used, the bore is made to extend only partially into the electrode body, if a sleeve is used the bore extends completely through the body. The pin or sleeve has smaller dimensions than the bore; if a pin is used it projects from one side of the electrode body and if a sleeve is used it projects from both sides of the electrode body. The electrode blank is subjected to a pyrolysis, whereby the cross-linked artificial resin is converted into vitreous carbon and the electrode body shrinks onto the pin or sleeve.

Abstract: An implantable heart defibrillator contains a pulse generator controlled by a control unit for emitting a number of heart stimulation pulses at a rate of several Hertz or more. The control unit causes the pulse generator to emit heart stimulation pulses with an energy content of the same, or somewhat greater, magnitude than conventional pacemaker pulses for a period of time long enough for the entire heart to become refractory.

Abstract: A device for detecting hemodynamic conditions in a heart, in particular conditions corresponding to dangerous arrhythmias contains a sensing unit for a physiological variable, such as blood pressure, the unit emitting a signal on the basis of the variable having an average value, a signal conditioning unit connected to the sensing unit, a calculation unit connected to the signal conditioning unit and a comparator after the calculation unit. The calculation unit is devised to calculate a variability measure relative to the signal's average value, the variability measure being correlated to average blood pressure, and the variability measure is compared in the comparator to an adjustable threshold value corresponding to a specific hemodynamic condition, whereupon the comparator emits an indication signal when the variability measure falls below the threshold value.

Abstract: A device for transmitting binary information, in the form of two information-carrying symbols, between two or a number of units, in which transmission is by optical means in free medium, includes an optical transmitter module with a transmitter unit for transmitting an optical transmission signal and an optical receiver module with a receiver unit for receiving the optical transmission signal, and the device is arranged for high speed communications without a carrier wave. The transmitter module is equipped with a formatting unit devised to activate the transmitter unit to emit the transmission signal only during part of a complete symbol interval corresponding to one of the symbols, and the receiver module is equipped with a normalizing unit devised to recreate, from the transmission signal received by the receiver unit, both the symbol corresponding to the transmission signal throughout its entire symbol interval and the residual information-carrying symbol in the digital information.

Abstract: In a method for manufacturing a working electrode for an implantable, electrochemical oxygen sensor a thin layer of a uniform mixture composed of an epoxy-based resin, a hardener and powdered vitreous carbon is applied onto a ring or hollow cylinder of biocompatible, inert, electrically conductive material, and the resin is hardened.

Abstract: An electrode device, for intracardiac stimulation of heart tissue and/or sensing heart signals in a patient, has an electrode cable containing at least two elongate, flexible conductors, insulated from each other, and with an electrode head, arranged at the distal end of the electrode cable and at least two conductive surfaces, each connected to a separate conductor. In order to permit the distance between the conductive surfaces to be varied over a continuous range, simply and easily, the electrode head has at least two parts, moveable in relation to each other, each part being provided with at least one conductive surface, and the a control element is movably arranged at the distal end of the electrode cable immediately behind the electrode head, so any change in the position of the control element causes the control element to act on the parts of the electrode head such that the distance between the conductive surfaces is varied.

Abstract: In a method and apparatus for determining whether electrical signals in a heart are caused by atrial depolarizations or ventricular depolarizations, heart signals are sensed in the upper part of the ventricular heart tissue, preferably the upper part of the ventricular septum. The detection of heart signals from both the atrium and ventricle and the identification of depolarization is facilitated if the course of the signals is monitored, with monophasic heart signals being caused by an atrial depolarization and biphasic signals being caused by a ventricular depolarization.

Abstract: In a method for measuring the flow of an electrolytic fluid, the voltage or current is measured between two stationary electrodes immersed in the electrolytic fluid. A device for measuring the flow has at least two electrodes intended for immersion in the electrolyte. The electrodes are stationary, and a measurement unit is arranged to measure the voltage or current between the electrodes.

Abstract: In a method for manufacturing electrodes for medical applications, particularly implantable stimulation electrodes, having an active layer of porous titanium nitride, a substrate of electrically conductive material that is in an atmosphere containing titanium, nitrogen and hydrogen is irradiated with an excimer laser through an optical mask, and a structure of porous titanium nitride is deposited on the substrate.