Abstract: A sensor arrangement, and a heart stimulator employing such a sensor arrangement, identify bending of an electrode lead. A lead which is implantable in a patient is subjected to bending due to movement of the surrounding tissue, and the lead has a deformation sensor therein which emits an electrical signal dependent on the magnitude and orientation of the bending. The deformation sensor can be formed by two parallel channels extending from the tip of the lead within an insulating sleeve of the lead which encloses a conductor element. The channels are filled with an electrically conductive fluid and are connected at their opposite ends to a resistance measuring unit. Bending of the lead causes the resistance of the fluid to change, which is measured by the resistance measuring unit. The channels can be disposed asymmetrically relative to a longitudinal axis of the lead, so that orientation of the bending can also be identified by comparing signals from the respective channels to each other.

Abstract: An implantable medical device, such as a cardiac stimulator, has a noise cancelling circuit which cancels noise signals relating to body movements which originate outside of the heart, and which are sensed between a noise sensing electrode located outside of the heart and the indifferent electrode of the stimulator housing. The noise cancelling circuit cancels these noise signals from the electrical signals which originate within the heart and which are sensed between the tip electrode of a stimulator lead and the indifferent electrode of the stimulator housing.

Abstract: A heart stimulator has a circuit for determining cardiac output and for producing a control signal corresponding to the determined cardiac output, and a controller for controlling cardiac stimulation dependent on the control signal. The circuit for determining cardiac output includes a pressure sensor which measures pressure in the right ventricle and which generates an electrical pressure signal corresponding to the measured pressure, and an integrator supplied with the pressure signal which integrates the pressure signal between a start time and stop time to produce an integration result corresponding to the cardiac output, which is used to form the control signal. The pressure signal is bandpass filtered during a systolic phase to identify opening of a valve at the right ventricle as the start time, and to identify closing of the valve as the stop time.

Abstract: An ischemia detector has a patient workload sensor and a patient breathing sensor which emits a signal representing sensed workload, and a patient breathing sensor which emits a signal representing sensed breathing activity of a patient. These signals are supplied to a detector unit which identifies a state of ischemia upon an occurrence of a predetermined relation between the sensed workload and the sensed breathing activity. This predetermined relation is a sensed low workload and a simultaneously sensed high breathing activity.

Abstract: An implantable heart stimulator has a control unit which controls the delivery of stimulation pulses to a subject, and an ischemia detector. The control unit is connected to the ischemia detector and reduces the stimulation rate in response to a detection of ischemia.

Abstract: An implantable stimulating device for electrical stimulation of a heart has a stimulus generator which generates electrical stimuli and at least one lead for delivering the stimuli from the generator to the heart. A measurement unit detects spontaneous intervals between successive intrinsic heartbeats, and forms an average of at least five of these spontaneous intervals. A variation with respect to this average for later spontaneous intervals is then identified, and this variation is then used to control a pacing parameter of the stimulus generator.

Abstract: An ischemia detector has a sensor unit which determines the systolic pressure of a subject, a unit wherein a relation is established between the systolic pressure and the subject's heart rate, as the heart rate is varied over a range, and an analyzer which determines the occurrence of ischemia from this relation.

Abstract: An ischemia detector includes repolarization sensor which senses repolarization of the heart of a patient and delivers corresponding repolarization signals to a detecting unit and a workload sensor which senses the workload of the patient and delivers corresponding workload signals to the detecting unit. The detecting unit identifies a state of ischemia as existing upon the occurrence of a predetermined relation between sensed repolarization and sensed workload.

Abstract: An implantable medical device has a pulse generator for generating electrical pulses, an electrical energy storage element connectable to an output stage, and an electrode arrangement for conducting the electrical pulses to tissue, the electrode arrangement having an input end and an output end. The output means of the pulse generator is connectable to the input end of the electrode arrangement, and the capacitance of the output stage is less than 1 .mu.F and the electrode arrangement has a capacitor with a capacitance greater than 1 .mu.F.

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: 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: An electrode apparatus, such as an intravascular or intracardiac pacemaker or defibrillation electrode with an electrode cable has a jacket of insulation enclosing a first elongated, flexible conductor, connected to a first electrode arranged on the electrode cable, and also enclosing at least a second conductor, connected to a conductive surface forming a second electrode arranged on the electrode cable at a distance from the first electrode.

Abstract: An electrode device, for intracardiac stimulation and/or defibrillation of heart tissue and/or sensing heart signals in a patient, has a soft, flexible electrode cable with an outer coating of insulation containing at least one elongate conductor connected to an electrode arranged on the electrode cable. In order to attain an electrode device of this kind which is structurally very simple and in which all the electrodes on the electrode cable can be applied to the heart wall in a very simple manner so the entire electrode surface faces the wall and firmly presses against it, the electrode cable is at least partially ribbon-shaped.

Abstract: A magnet position detector, particularly for implantable medical devices, has a resiliently supported coil, a current source delivering a current to the coil and a detecting device for detecting the movement of the coil in a magnetic field when fed with an electric current from the current source. The coil has a core with a non-linear B-H curve and the current source is a pulse source delivering current pulses with at least one positive and one negative side. The detecting device detects the movements of the coil in opposite directions respectively excited by differentiated signals respectively corresponding to the leading and trailing edges and permits the magnitudes of the respective, oppositely directed movements to be compared to each other, thereby indicating the position of a source of the magnetic field, relative to the coil, to be determined.

Abstract: A magnetic field detector, particularly for implantable medical apparatuses, has a coil mounted at the free end of a resilient member fixed at its opposite end portion, and a detecting device for detecting, as a measure of a magnetic field, the movement of the coil in the field when fed with an electric current from a controllable current source. The resilient member is bent to form at least two shanks interconnected at one end. The coil is mounted at the free end of one of the shanks and the resilient member is fixed at the free end portion of the other shank.

Abstract: A pacemaker has a pulse source for delivering heart stimulation pulses to at least one heart stimulation electrode which includes a source for charging a charge storage element with a prescribed amount of charge for each heart stimulus. The charge storage element is then caused to discharge a predetermined amount of charge through the stimulation electrode to form a heart stimulation pulse.

Abstract: A device for analyzing the function of a heart has an electrical measurement unit for generating a measurement signal related to an electrical or mechanical heart variable, and an evaluation unit for evaluating the measurement signal. The device further includes circuitry for generating at least one parameter signal from the measurement signal. The evaluation unit analyzes related values in the measurement signal and the parameter signal, these related values corresponding to coordinates which form a curve in a coordinate system, the measurement signal and the parameter signal serving as coordinate axes, by sensing the sequence in which the curve passes a predesignated number of areas in the coordinate system. The device is capable of detecting spontaneous and stimulated heartbeats, tachyarrhythmias, retrograde conduction, ectopic beats, etc.

Abstract: It is known that modern implantable electromedical devices for the stimulation of a physiological function, such as pacemakers, are programmable to work in different stimulating modes and comprise sensing and evaluating means for monitoring the capacity of the battery within the device. In order to achieve a constant time duration between the point in time when the battery capacity drops below a threshold value and the end of life of the battery, said threshold value is varied in dependence on the utilized stimulating mode in such a way that a higher threshold value is selected for a stimulating mode with a high energy consumption and vice versa.

Abstract: A medical device adapted to be implanted in a patient includes components for detecting physiological events and/or for stimulating physiological events, and includes control logic connected to the detecting and or stimulating components, and further components for the telemetric transmission of data relating to the logical status of the control logic to and from an external receiver. The components for telemetrically transmitting data are connected to the control logic, and continuously transmit data identifying the current logical status of the control logic to the external receiver.

Abstract: A pacemaker lead analyzer for measuring impedance during standard operation of an implanted pacemaker. The analyzer makes separate measurements of lead impedance during each heart signal and each pacing pulse. A moving average of measured parameters is maintained and recurring deviations from the norms are noted in separate event counters for subsequent analysis of the noted events as possible indications of impending failure of an implanted lead.