title: Improvement of hemocompatibility in centrifugal blood pump with hydrodynamic bearings and semi-open impeller: in vitro evaluation.
abstract: We have developed a noncontact-type centrifugal blood pump with hydrodynamic bearings and a semi-open impeller for mechanical circulatory assist. The impeller is levitated by an original spiral-groove thrust bearing and a herringbone-groove journal bearing, without any additional displacement-sensing module or additional complex control circuits. The pump was improved by optimizing the groove direction of the spiral-groove thrust bearing and the pull-up magnetic force between the rotor magnet and the stator coil against the impeller. To evaluate hemocompatibility, we conducted a levitation performance test and in vitro hemocompatibility tests by means of a mock-up circulation loop. In the hemolysis test, the normalized index of hemolysis was reduced from 0.721 to 0.0335 g/100 L corresponding to an expansion of the bearing gap from 1.1 to 56.1 microm. In the in vitro antithrombogenic test, blood pumps with a wide thrust bearing gap were effective in preventing thrombus formation. Through in vitro evaluation tests, we confirmed that hemocompatibility was improved by balancing the hydrodynamic fluid dynamics and magnetic forces.
authors.affiliation: National Institute of Advanced Industrial Science and Technology, Institute for Human Science and Biomedical Engineering, Tsukuba, Ibaraki, Japan. ryo.kosaka@aist.go.jp
authors.forename: Ryo
authors.initials: R
authors.lastname: Kosaka
authors.forename: Osamu
authors.initials: O
authors.lastname: Maruyama
authors.forename: Masahiro
authors.initials: M
authors.lastname: Nishida
authors.forename: Toru
authors.initials: T
authors.lastname: Yada
authors.forename: Sakae
authors.initials: S
authors.lastname: Saito
authors.forename: Shusaku
authors.initials: S
authors.lastname: Hirai
authors.forename: Takashi
authors.initials: T
authors.lastname: Yamane
mesh_terms: D000818:Animals; D002417:Cattle; D004867:Equipment Design; D006353:Heart-Assist Devices / Q000009:adverse effects; D006461:Hemolysis; D018056:Hemorheology; D008280:Magnetics; D008422:Materials Testing; D012399:Rotation; D013314:Stress, Mechanical; D013927:Thrombosis / Q000209:etiology / Q000517:prevention & control; D013997:Time Factors