title: Effect of a bearing gap on hemolytic property in a hydrodynamically levitated centrifugal blood pump with a semi-open impeller.
abstract: We have developed a hydrodynamically levitated centrifugal blood pump with a semi-open impeller for long-term circulatory assist. The pump uses hydrodynamic bearings to enhance durability and reliability without additional displacement-sensors or control circuits. However, a narrow bearing gap of the pump has a potential for hemolysis. The purpose of this study is to develop the hydrodynamically levitated centrifugal blood pump with a semi-open impeller, and to evaluate the effect of a bearing gap on hemolytic property. The impeller levitates using a spiral-groove type thrust bearing, and a herringbone-groove type radial bearing. The pump design was improved by adopting a step type thrust bearing and optimizing the pull-up magnetic force. The pump performance was evaluated by a levitation performance test, a hemolysis test and an animal experiment. In these tests, the bearing gap increased from 1 to 63 μm. In addition, the normalized index of hemolysis (NIH) improved from 0.415 to 0.005 g/100 l, corresponding to the expansion of the bearing gap. In the animal experiment for 24 h, the plasma-free hemoglobin remained within normal ranges (<4.0 mg/dl). We confirmed that the hemolytic property of the pump was improved to the acceptable level by expanding the bearing gap greater than 60 μm.
authors: Human Technology Research Institute, National Institute of Advanced Industrial Science and Technology, Ibaraki, Japan. ryo.kosaka@aist.go.jp
authors: Ryo
authors: R
authors: Kosaka
authors: Masahiro
authors: M
authors: Nishida
authors: Osamu
authors: O
authors: Maruyama
authors: Tomoyuki
authors: T
authors: Yambe
authors: Kou
authors: K
authors: Imachi
authors: Takashi
authors: T
authors: Yamane
mesh_terms: D000818:Animals; D002498:Centrifugation / Q000295:instrumentation; D004867:Equipment Design; D005260:Female; D006041:Goats; D006353:Heart-Assist Devices; D006461:Hemolysis; D057446:Hydrodynamics; D008280:Magnetics / Q000295:instrumentation / Q000379:methods; D015203:Reproducibility of Results