Abstract: A rate controlled cardiac pacemaker stimulates the heart of a patient at a stimulation rate and includes a stress sensor for sensing actual physical stress of the patient. The device includes control logic for adapting the stimulation rate of the pacemaker to the actual physical stress of the patient and determining circuitry for determining the activity of the patient. The determining circuitry includes an activity sensor for sensing the activity state of the patient and a rate control circuit having an input connected with an output of the activity sensor. A timer generates a signal based on a 24-hour rhythm indicating a rest phase or an activity phase, and is synchronized by the activity sensor in a 24-hour rhythm with patient activity and rest phases that occur in continuous alternation.

Abstract: A cardiac pacemaker implantable in a patient, including: a unit for apply stimulating pulses to the heart of the patient; a device for detecting at least one physiological parameter which is a function of left-ventricular systolic time intervals of the heart; a circuit connected to the detecting device for deriving a reference value which is a function of the physiological parameter; and a signal circuit connected between the circuit and the pulse applying unit for producing stimulating pulses at a rate based on the reference value in the absence of spontaneous heart action.

Abstract: Pacer control information adapting the pacers to an individual relating a ysiological parameter obtained from a first sensor to a corresponding parameter obtained from a second sensor is stored in a memory for later address in response to a signal from the first sensor to provide the corresponding pacer control information to the pacer generator.

Abstract: A pacemaker electrode has an axially open, hollow cylinder, a plunger axiy displaceably received in the cylinder and a securing element for attaching the electrode to the heart. The securing element is mounted on the plunger for movement therewith as a unit. The securing element and the plunger have a withdrawn position in which the securing element is in a substantially fully retracted state within the cylinder. Further, the securing element and the plunger have an advanced position in which the securing element projects from the cylinder. The cylinder has a portion which is substantially pervious to X-rays. The plunger substantially blocks the path of X-rays across the cylinder through the X-ray pervious portion when the plunger and the securing element are in the withdrawn position.

Abstract: A signal processing device composed of: a signal input for receiving an electrocardiographic signal containing a succession of QRS complexes; a signal output; a digitally operating unit having a transmission factor which is variable in discrete steps and connected between the signal input and output for supplying to the signal output a signal containing representations of the QRS complexes contained in the signal received by the signal input, with the relation between the amplitude of the signal at the signal output and the amplitude of the corresponding portions of the signal received by the signal input being proportional to the existing transmission factor of the digitally operating unit; and a transmission factor control unit connected to monitor the signal at the signal output for increasing the transmission factor of the digitally operating unit by one step in response to each appearance at the signal output of a QRS complex representation having a peak value between selected first and second threshold