The invention relates to the field of blood pumps.
A blood pump here and hereinafter is to be understood as a pump which serves for supporting or creating a blood flow within a human or animal body and is suitable for implantation into the thorax of a human or animal, outside the heart. With left ventricular assist devices (LVAD), a connection exists between the left heart half and an inlet of the blood pump as well as between the outlet of the blood pump and the aorta departing from the heart, for the support or creation of the blood circulation through the body (systemic circulation). With right ventricular assist devices (RVAD) there exists a connection between the right heart half and the pulmonary artery stem which leads to the left and to the right pulmonary artery, (or a direct connection between the RVAD and the left and/or right pulmonary artery) for the support or creation of the blood circulation through the lung (pulmonary circulation). The blood, within the blood pump, is led through a hollow body which is part of a pump housing or is arranged in such a pump housing. A rotating impeller, with a blading for producing a pressure and a flow of the blood resulting therefrom, is provided in the hollow body. So-called total artificial hearts (total heart pumps) contain a left ventricular and a right ventricular assist device (blood pump) for the support or the creation of the complete blood circulation. Flexible connection tubes or connection pipes as well as, as the case may be, flow bends or elbows, are applied for creating the mentioned connections between the blood pump and the heart or blood vessels. Moreover, at least one cable line is necessary for the energy supply and, as the case may be, for the control of the blood pump, said cable line connecting the blood pump to an energy storer and, as the case may be, to a control unit.
A main problem with the implantation and the use of such blood pumps, in particular total artificial hearts, is the spatial requirement of such blood pumps and the flexible connection tubings as well as the cable line in the thorax space in the vicinity of the heart.
A further difficulty lies in the danger of destruction of the blood cells (hemolysis) due to the blood pump, in particular at the mechanical bearings of the impeller, narrowings and abrupt changes in direction of the blood flow through the blood pump, as well as by way of large pressure gradients within the blood pump. With the design of blood pumps, for this purpose, often mechanical bearings of the impeller are replaced by a magnetic and/or hydrodynamic bearing.
An additional problem lies in the fact that a significantly smaller blood pressure needs to be created for the pulmonary circulation, than for the systemic circulation, wherein however the same blood volume per time needs to be transported through both blood circulations. The blood pressure produced by the blood pump depends on the rotational speed of the impeller of the blood pump. It has been found to be difficult to design a pump which is suitable for setting very different values of the blood pressure within a range of about 5 mmHg up to about 150 mmHg with a stable, constant volume flow between 0 l/min to 20 l/min adapted to the physiological conditions, and which in this manner may be applied as an RVAD as well as an LVAD, or which is suitable for the design of a total artificial heart.
It is therefore the object of the present invention, to suggest a blood pump as well as a total artificial heart, which solves or at least reduces the problems mentioned above. A corresponding blood pump or total artificial heart should thus have an as low as possible spatial requirement and be suitable for the support or creation of blood pressure, in a manner which as gentle as possible to the blood. Moreover, it should be suitable for covering a large range of the blood pressure with an as suitable as possible volume flow.