Abstract: A method for processing a signal characteristic of cardiac activity in the atrium (A) and/or ventricle (V) of a heart (H) and for evaluating this signal with a view to obtaining a control signal for a cardiac pacemaker and/or defibrillator (3) can be carried out by: receiving a time dependent signal from at least one intracardial signal sensor (1, 2) in the atrium and/or ventricle; feeding the signal picked up by each signal sensor (1, 2) to a read and evaluation circuit (6) with a threshold characteristic; comparing the signals with a detection threshold; evaluating the result of the comparison to obtain an indication as to the presence of normal sinus-type cardiac activity or fibrillations; and producing the control signal, which characterizes the comparison result.

Abstract: An arrangement is provided for controlling a stimulation frequency of a pacemaker. The arrangement includes an atrial bipolar electrode system and a ventricular bipolar electrode system. A first electrode pair comprises an electrode from each of the atrial and ventricular bipolar electrode systems, with the electrodes of the first electrode pair being disposed intracardially in the atrium and ventricle, respectively. A pacemaker control unit generates stimulation pulses for stimulating the heart. A constant current source impresses a constant current to a second electrode pair, comprising at least one electrode from one of the atrial and ventricular bipolar electrode systems being disposed intracardially in one of the atrium and ventricle, for developing an electrical potential between the electrodes of the first electrode pair during predetermined cardiac phases.

Abstract: An ultrasound apparatus permitting dynamic variation of the position of the reception focus of a prescribable number of ultrasound transducer elements has a reception channel including a time-delay circuit for the received ultrasound echo signal following every ultrasound transducer element. For switching between different, prescribed time-delay values (T.sub.1, T.sub.2, . . . T.sub.n), the time-delay circuit is connected to a control device. A part of the time-delay circuit is redundantly designed, so that first and a second sub-circuits for forming the time-delayed ultrasound echo signal are present. A dissolve circuit is provided which causes the second sub-circuit to be faded in the reception channel when the first sub-circuit, in a blanked condition, is switched to a different time-delay value (T.sub.1, T.sub.2, . . . T.sub.n), and vice versa, by a control device. Significant time is thus saved when switching between the different focus positions of the ultrasound apparatus.