Effect of a bearing gap on hemolytic property in a hydrodynamically levitated centrifugal blood pump with a semi-open impeller

Ryo Kosaka, Masahiro Nishida, Osamu Maruyama, Tomoyuki Yambe, Kou Imachi, Takashi Yamane

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)

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.

Original languageEnglish
Pages (from-to)37-47
Number of pages11
JournalBio-medical materials and engineering
Volume23
Issue number1-2
DOIs
Publication statusPublished - 2013

Keywords

  • Hydrodynamic bearing
  • animal experiment
  • bearing gap
  • hemolysis
  • step type thrust bearing

ASJC Scopus subject areas

  • Biomaterials
  • Biomedical Engineering

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