When a patient’s heart disease cannot be treated, heart transplantation is required, but only a few people can receive transplants. These rare opportunities for transplantation have created a demand for artificial hearts.
The mechanical action of the current generation of heart pumps causes blood coagulation (thrombogenesis) and blood cell destruction (hemolysis). To reduce thrombogenesis, an artificial heart pump should be configured to reduce the number of structural components that may hinder the blood, enable the blood flow channel to have a large diameter, operate stably, and reduce the displacement of movable structural components. To reduce hemolysis, an artificial heart should shorten the length of the blood flow channel and lower the rotation speed of the movable structural components.
There are four types of artificial hearts: diaphragm, tube, roller pressure, and radial flow/centrifugal. In the current generation of pumps, however, problems include long blood flows apt to create blood cell destruction, unstable rotation because of drive motor position, and outside supporting magnets located within the blood flow channel, causing blood flow stagnation and clotting. In this design, no structural component such as a magnet hinders the flow of the blood channel, so it is possible to suppress blood flow stagnation and blood coagulation from occurring.
This technology is a single-pivot centrifugal pump that can be used before and after surgery. The non-contact rotating pump uses a centrifugal pump with a non-contact hydrodynamic bearing that can be implanted in the body for long periods of time.
The single-pivot centrifugal pump was designed for external use as a circulatory assist pump that can be used for two weeks or more. External circulatory assist pumps are used before and after surgery. We are performing flow visualization experiments and pivot wear testing to resolve the problems of blood cell damage, clotting, and mechanical wear that occur at pivot bearings.
The impeller is 50 mm in diameter and levitates on two thrust bearings (top and bottom) and a radial bearing. The impeller levitates about 20 micrometers, which leads to blood clots and damage to blood cells. After doing fluid dynamic analysis, the design was altered to give it a deeper hydrodynamic groove. The estimated bearing flow was increased, which resolved inter-bearing clotting.
This technology is offered by AIST, Japan’s National Institute of Advanced Industrial Science and Technology. For more information, view the yet2.com TechPak at http://info.hotims.com/28057-154.