Pumps – Including disengageable rotary or frangible drive connection
Patent
1998-12-16
2000-09-12
Walberg, Teresa
Pumps
Including disengageable rotary or frangible drive connection
417366, 417420, 4174231, 41742312, 604151, F04B 900
Patent
active
061168629
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention refers to a blood pump, preferably to an implantable blood pump for supporting or replacing the cardiac function on the left and/or the right hand side.
From U.S. Pat. No. 4,994,078, an implantable blood pump is known that is shaped like a snail shell, the stator of the motor being integrated in the pump housing, while the rotor is firmly connected to a pump impeller wheel and is flushed by the blood flow. Thus, the blood flows through the inside of the motor, with one wall of the annular channel formed by the motor being stationary, while the other wall rotates. This gives rise to the risk of damage to the blood caused by shear forces occurring there.
EP 0 611 580 A2 describes an artificial cardiac pump, wherein blood also flows around the rotor and the stator of the motor. At the outlet side, a pump impeller wheel is arranged that is designed as a radial pump and pumps blood, drawn axially along the stator, into a surrounding annular channel from which the blood exits tangentially. Here, there are two suction paths, namely the main suction path surrounding the stator and a relatively narrow annular channel between the stator and the rotor. Again, there is a risk of damaging the blood by shear forces.
Finally, a blood pump is known from WO 94/09274 that has a helical rotor surrounding a stator.
It is the object of the present invention to provide a blood pump in which damage to the blood and thrombogenesis are substantially avoided.
According to the invention, the object is solved with the features of claim 1.
SUMMARY OF THE INVENTION
In the blood pump of the present invention, the motor is disposed coaxially as a self-contained unit inside an elongate pump housing, an annular channel being formed between the pump housing and the motor housing, through which channel blood flows. The pump impeller wheel is arranged at the inlet end of the motor and, together with a transition portion of the pump housing, forms a pump that is flown through diagonally and creates an whirling axial flow flowing annularly around the motor housing. Thus, in the region of the motor, the blood flows between two stationary parts, namely the pump housing and the motor housing, whereby additional shearing stresses of the blood outside the rotating part of the pump blades are avoided. The blood flow passing along the motor housing causes a constant cooling of the motor for as long as the motor operates. Accordingly, the motor is cooled by the blood flowing along the same. The pump housing is elongate and substantially tubular and formed without any rotating annular channels or other enlargements. This allows for a simple and compact implantation in the vicinity of the heart, taking into consideration the physiological boundary conditions.
The axial blood flow along the pump housing may have a circumferential component, the blood flowing helically around the motor housing. The pump housing has a length of about 5 to 10 cm and an outer diameter of about 2 to 3 cm. The inlet and the outlet are tapered with respect to the outer diameter of the pump housing.
In a preferred embodiment of the blood pump, the outlet exits on the side of the pump housing. Here, an end wall may be provided at the outlet end of the pump housing, the wall including a helical channel leading to the outlet at the angle of the flow present there. Such a blood pump is particularly suited for patients having irreversible cardiac failure of the left ventricle. In this case, a connection site is inserted into the ventricle so that the same is relieved by taking blood therefrom. The connection site is connected to the pump inlet, while the outlet of the pump is connected to the aorta. The outlet of this embodiment, shifted by about 90.degree. with respect to the inlet, is physiologically favorable also for a cannulation between left atrium and aorta.
The connection of the inlet of the blood pump with the atrium may be closed again after removal of the connection site. Thus, the heart may return to working on its own
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patent: 6042347 (2000-03-01), Scholl et al.
Rau Guenter
Reul Helmut
Siess Thorsten
MEDOS Medizintechnik GmbH
Pwu Jeffrey
Walberg Teresa
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