Implantable centrifugal blood pump with hybrid magnetic bearings

Abstract

A pump for pumping sensitive fluids, such as blood, has no mechanical contact between the impeller and any other structure.

Description

RELATED APPLICATION[0001]This application is a continuation of and claims priority to U.S. patent application Ser. No. 09 / 673,922, filed Oct. 24, 2001, entitled “Hybrid Magnetically Suspended and Rotated Centrifugal Pumping Apparatus and Method,” which is the National Stage of International Application No. PCT / US99 / 08870, filed Apr. 22, 1999, entitled “Implantable Centrifugal Blood Pump With Hybrid Magnetic Bearings,” which claims priority from abandoned U.S. patent application Ser. No. 09 / 064,352, filed Apr. 22, 1998, entitled “Implantable Centrifugal Blood Pump With Hybrid Magnetic Bearings,” which was a continuation-in-part of U.S. patent application Ser. No. 08 / 850,598, filed May 2, 1997, entitled “Hybrid Magnetically Suspended and Rotated Centrifugal Pumping Apparatus and Method,” now U.S. Pat. No. 6,074,180, which claims priority from U.S. Provisional Patent Application No. 60 / 016,856, filed May 3, 1996, entitled “Hybrid Magnetically Suspended and Rotated Centrifugal Pumping A...

AI Technical Summary

Benefits of technology

"This patent describes a pump system for sensitive fluids such as blood that can be implanted in the human body. The system uses magnetic bearings to gently handle the fluid with low heating. The pump is small and can be used as a heart assist device or replacement heart. It has a long life with minimal maintenance. The pump can provide constant or pulsed flow and can change direction of the fluid without damaging it. The system includes a motor and magnetic bearing system that are controlled by a controller that senses the position of the impeller without needing additional sensors. The pump is suitable for short or long-term implantation and can be used as a ventricular assist device or replacement heart."

Problems solved by technology

However, pumps for pumping sensitive fluids, such as blood, introduce special design requirements.

The design problems associated with sensitive fluids, including blood, generally relate to problems caused by contact of the fluid with mechanical parts and other substances present in the pump.

For example, it is well known that rotating shaft seals are notoriously susceptible to wear, failure, and even attack by some fluids.

Many types of pumps may also increase mechanical working of the fluid and precipitate detrimental processes such as chemical reactions or blood clotting.

Thus, rolling element bearings are generally not practical for blood pumps.

However, such pumps known in the art present several drawbacks.

First, an external motor with its own means of bearing support (ball bearings) is still required to rotate the impeller.

Though the motor is sealed from contact with blood and other bodily fluids, and is magnetically coupled to the suspended impeller, it still employs bearings which produce heat and pose the potential of failure.

Naturally, such pumps tend to be bulky in part because of the size of the electric motor.

These pumps are frequently unsuitable for implantation in a human patient because of size, weight, power consumption, and durability problems.

This approach also leaves certain problems unsolved.

These problems are well known by designers of electromechanical devices, where significant steps are normally taken to reduce the dependency of device performance on homogeneous magnets.

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