title: An implantable centrifugal blood pump with a recirculating purge system (Cool-Seal system).
abstract: A compact centrifugal blood pump has been developed as an implantable left ventricular assist system. The impeller diameter is 40 mm, and pump dimensions are 55 x 64 mm. This first prototype, fabricated from titanium alloy, resulted in a pump weight of 400 g including a brushless DC motor. The weight of a second prototype pump was reduced to 280 g. The entire blood contacting surface is coated with diamond like carbon (DLC) to improve blood compatibility. Flow rates of over 7 L/min against 100 mm Hg pressure at 2,500 rpm with 9 W total power consumption have been measured. A newly designed mechanical seal with a recirculating purge system (Cool-Seal) is used for the shaft seal. In this seal system, the seal temperature is kept under 40 degrees C to prevent heat denaturation of blood proteins. Purge fluid also cools the pump motor coil and journal bearing. Purge fluid is continuously purified and sterilized by an ultrafiltration unit which is incorporated in the paracorporeal drive console. In vitro experiments with bovine blood demonstrated an acceptably low hemolysis rate (normalized index of hemolysis = 0.005 +/- 0.002 g/100 L). In vivo experiments are currently ongoing using calves. Via left thoracotomy, left ventricular (LV) apex descending aorta bypass was performed utilizing an expanded polytetrafluoroethylene (ePTFE) vascular graft with the pump placed in the left thoracic cavity. In 2 in vivo experiments, the pump flow rate was maintained at 5-9 L/min, and pump power consumption remained stable at 9-10 W. All plasma free Hb levels were measured at less than 15 mg/dl. The seal system has demonstrated good seal capability with negligible purge fluid consumption (<0.5 ml/day). In both calves, the pumps demonstrated trouble free continuous function over 6 month (200 days and 222 days).
authors.affiliation: Tokyo Women's College, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Yamazaki
authors.forename: P
authors.initials: P
authors.lastname: Litwak
authors.forename: O
authors.initials: O
authors.lastname: Tagusari
authors.forename: T
authors.initials: T
authors.lastname: Mori
authors.forename: K
authors.initials: K
authors.lastname: Kono
authors.forename: M
authors.initials: M
authors.lastname: Kameneva
authors.forename: M
authors.initials: M
authors.lastname: Watach
authors.forename: L
authors.initials: L
authors.lastname: Gordon
authors.forename: M
authors.initials: M
authors.lastname: Miyagishima
authors.forename: J
authors.initials: J
authors.lastname: Tomioka
authors.forename: M
authors.initials: M
authors.lastname: Umezu
authors.forename: E
authors.initials: E
authors.lastname: Outa
authors.forename: J F
authors.initials: JF
authors.lastname: Antaki
authors.forename: R L
authors.initials: RL
authors.lastname: Kormos
authors.forename: H
authors.initials: H
authors.lastname: Koyanagi
authors.forename: B P
authors.initials: BP
authors.lastname: Griffith
mesh_terms: D000497:Alloys; D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry; D001769:Blood; D001794:Blood Pressure; D001798:Blood Proteins / Q000737:chemistry; D001807:Blood Vessel Prosthesis; D002244:Carbon / Q000737:chemistry; D002417:Cattle; D018130:Diamond / Q000737:chemistry; D011211:Electric Power Supplies; D004560:Electricity; D005500:Follow-Up Studies; D006353:Heart-Assist Devices; D006454:Hemoglobins / Q000032:analysis; D006461:Hemolysis; D018056:Hemorheology; D006358:Hot Temperature; D011138:Polytetrafluoroethylene; D011474:Prosthesis Design; D011489:Protein Denaturation; D013499:Surface Properties; D014025:Titanium; D014462:Ultrafiltration / Q000295:instrumentation
chemical_list: D000497:Alloys; D001672:Biocompatible Materials; D001798:Blood Proteins; D006454:Hemoglobins; C031462:titanium alloy (TiAl6V4); D002244:Carbon; D018130:Diamond; D011138:Polytetrafluoroethylene; D014025:Titanium