Rotary Blood Pump

Abstract

The present invention provides a rotary blood pump with both an attractive magnetic axial bearing and a hydrodynamic bearing. In one embodiment according to the present invention, a rotary pump includes an impeller assembly supported within a pump housing assembly by a magnetic axial bearing and a hydrodynamic bearing. The magnetic axial bearing includes at least two magnets oriented to attract each other. One magnet is positioned in the spindle of the pump housing while the other is disposed within the rotor assembly, proximate to the spindle. In this respect, the two magnets create an attractive axial force that at least partially maintains the relative axial position of the rotor assembly. The hydrodynamic bearing is formed between sloping surfaces that form tight clearances below the rotor assembly.

Description

RELATED APPLICATIONS [0001] This application claims priority to U.S. Provisional Application Ser. No. 60 / 787,738 filed Mar. 31, 2006 entitled Rotary Blood Pump which is hereby incorporated by reference.BACKGROUND OF THE INVENTION [0002] Blood pumps remain particularly useful for the treatment of cardiac disease and especially heart failure. Typically, blood pumps are implanted within a patient and connected to the patient's circulatory system as a ventricular assist device or, in some circumstances, as an artificial heart. However, the fragile nature of blood and the absolute necessity of the pump's reliability have presented numerous obstacles to designing a more perfect blood pump. [0003] For example, most blood pumps contain moving parts, such as an impeller, that force blood into and out of the pump housing. If these moving parts are not properly designed and adjusted, the blood passing through the pump can be damaged, causing hemolysis or thrombosis. Further, these moving parts...

AI Technical Summary

Benefits of technology

[0010] It is another object of the present invention to provide a rotary pump that minimizes damage to a patient's blood.

[0011] It is yet another object of the present invention to provide a rotary pump that includes reduced power consumption over prior art designs.

[0012] It is another object of the present invention to provide a rotary pump that more efficiently pumps blood through a circulatory system of a patient.

[0049] Another preferred embodiment of the present invention includes a method of pumping blood comprising: providing a pump housing defining a pump chamber moving blood from an inlet in said pump housing through an impeller of said pump chamber to an outlet in said pump housing; and increasing the pressure of said blood in said pump chamber upstream of said outlet so as to force a leakage flow blood between mating surfaces of said impeller and said pump housing.

[0052] In another aspect of this preferred embodiment passing blood through a throttling volute in said pump chamber comprises increasing the pressure inside the pump relative to the outlet between about 50% and about 100%.

Problems solved by technology

However, the fragile nature of blood and the absolute necessity of the pump's reliability have presented numerous obstacles to designing a more perfect blood pump.

If these moving parts are not properly designed and adjusted, the blood passing through the pump can be damaged, causing hemolysis or thrombosis.

Further, these moving parts can wear on each other, causing an increased likelihood of part failure and heat buildup that is imparted to the blood.

Both blood pumps suffer from hydraulic inefficiencies due at least in part to the large, unconventional impeller blade geometry required for containing the motor rotor magnets.

Further inefficiencies of these designs arise because of the natural attraction between the motor rotor magnets of the impeller and the back iron of the electromagnets.

Additionally, these blood pump designs exclusively rely on hydrodynamic bearing for axial support, which can result in excessive shear forces that can damage the blood and cause medical complications in the patient's health.

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