Abstract: The pump (10) has variable volume means (24) co-operating with a distinct volume (20) through which the blood flows for the purpose of varying said volume (20) through which the blood flows in cyclical and controlled manner. According to the invention, the control circuit for the pump comprises: means for sensing data representative of aortic pressure (P(t)); means for sensing data representative of venous oxygen concentration (PO.sub.2V); means for sensing data representative of aortic oxygen concentration (PO.sub.2A); means for sensing data representative of heartbeat frequency (F); and/or means for sensing data representative of the myocardial contractility (dP/dt). The circuit can control the rates (u(t), v(t)) at which said volume varies during the systolic and diastolic phases of the myocardium, and also the instants (t.sub.A ; t.sub.R) at which said variation of the volume starts during the systolic and diastolic phases.

Abstract: The pump comprises: an essentially rigid body open at both ends and designed to be inserted in the down aorta artery; a flexible and elastic membrane (18) in the form of a sleeve connected in sealed manner to the body at the periphery of the ends thereof so as to define firstly, between the body and the sleeve, a closed intermediate space (20) of variable volume, and secondly, inside the sleeve, a variable volume (22) through which the blood to be pumped passes; and means for connecting the intermediate space to a source of hydraulic fluid suitable for causing the membrane to pass from a free state to a tensioned state in which it is urged radially inwards, thereby correspondingly reducing the volume through which the blood passes, and vice versa.

Abstract: A pump comprises variable volume means inserted in an artery, in particular, the descending aorta, enabling the volume through which the blood flows in this location to be modified cyclically and in a controlled manner. The device comprises a deformable enclosure in fluid communication with the variable volume. The variable volume and a spring coil urge the deformable enclosure against an increase of volume resulting from a pressure increase in the variable volume, and in the corresponding enclosure, in a way which produces additional elastance for the artery during the heart cycle. In addition, an electric motor can control the deformable enclosure to increase or decrease its volume, and can exert its force in addition to or in subtraction from the force of the spring coil during the systolic and diastolic phases of the heart cycle. This produces an additional pumping effect on arterial blood and correspondingly relieves the effort required of the heart.

Abstract: A heart signal sensor 11 is connected by a flexible cord 13 to a catheter 17. The sensor 11 and the catheter 17 are attached to install the sensor in the cardiac wall, and thereafter are disunited and separately attached to the cardiac wall 1. The sensor is attached to the cardiac wall by claws projecting from the sensor surface, and may be installed by rotating or by deformation of the sensor.