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Ando M.,Japan National Cardiovascular Center Research Institute | Ando M.,University of Tokyo | Nishimura T.,University of Tokyo | Takewa Y.,Japan National Cardiovascular Center Research Institute | And 7 more authors.
Journal of Artificial Organs | Year: 2011

Recent developments in adjunct therapeutic options for end-stage heart failure have enabled us to remove implanted left ventricular assist devices (LVADs) from more patients than before. However, a safe and proper protocol for pump-off trials is yet to be established, because diastolic backward flow in a pump circuit turns up when it is driven at low-flow conditions. We have developed a novel drive mode of centrifugal pumps that can change its rotational speed in synchronization with the cardiac cycle of the native heart. The purpose of this study was to test-drive this novel system of a centrifugal pump in a mock circulation and to evaluate the effect of the counterpulse mode, which increases pump speed just in diastole, on the amount of this nonphysiological intracircuit retrograde flow. A rotary pump (EVAHEART, Sun Medical Technology Research Corporation) was connected to the mock circulation by left ventricular uptake and ascending aortic return. We drove it in the following four conditions: (A) continuous mode at 1500 rpm, (B) counterpulse mode (systolic 1500 rpm, diastolic 2500 rpm), (C) continuous mode at 2000 rpm, and (D) counterpulse mode (systolic 2000 rpm, diastolic 2500 rpm). Data concerning the rotation speed, pump flow, left ventricular pressure, aortic pressure, and pressure head (i.e., aortic pressure-left ventricular pressure) in each condition were collected. After data collection, we analyzed pump flow, and calculated its forward and backward flow. Counterpulse mode decreased the amounts of pump backward flow compared with the continuous mode [mean backward flow, -4, -1, -0.5, 0 l/min, in (A), (B), (C), and (D) conditions, respectively]. The actual amounts of mean backward flow can be different from those in clinical situations; however, this novel drive mode for rotary pumps can relatively decrease pump backward flow during pump weaning and can be beneficial for safe and proper pump-off trials. Further investigations in in vivo settings are currently ongoing. © 2011 The Japanese Society for Artificial Organs. Source


Ando M.,Japan National Cardiovascular Center Research Institute | Ando M.,University of Tokyo | Nishimura T.,University of Tokyo | Takewa Y.,Japan National Cardiovascular Center Research Institute | And 7 more authors.
Journal of Artificial Organs | Year: 2011

Bridge to recovery has become a major goal after left-ventricular-assist- device (LVAD) implantation thanks to recent development in adjunctive therapies. Precise assessment of native heart function under minimum LVAD support is the key for successful LVAD explantation. However, weaning of centrifugal LVADs normally generates diastolic intracircuit backward flow. This retrograde flow may become excessive load for the native heart during off-pump test. The flow itself is an inevitable characteristic of centrifugal pumps. Therefore, evaluating this retrograde flow in vitro is of considerable significance, even if its amount is different from that in clinical settings. The purpose of this study was to assess diastolic backflow of continuous-flow centrifugal LVADs in a mock circulation model. A centrifugal LVAD (EVAHEART, Sun Medical Technology) was installed in a mock circulation model by the left ventricle uptake and the ascending aortic return. Pump flow was measured at the pump rotational speed of 1000, 1500, 2000, and 2500 rpm, and pulse rate of the virtual native heart was varied to 60, 90, and 120 beats/min. After data collection, pump flow was integrated, and forward and backward intracircuit flow were calculated. As a result, nonphysiological reverse flow of approximately 2.0 L/min exists at the rotational speed, providing 0 L/min mean pump flow. An ideal off-test trial condition should be realizing both ±0 L/min pump flow and no intracircuit backward flow at the same time. We are developing a novel EVAHEART drive mode that can change its rotational speed in synchronization with cardiac cycle with the aim of controlling this retrograde flow with the new drive mode and creating an ideal off-test condition. © 2011 The Japanese Society for Artificial Organs. Source


Yamane T.,Japan National Institute of Advanced Industrial Science and Technology | Yamane T.,Kobe University | Nishida M.,Japan National Institute of Advanced Industrial Science and Technology | Kawamura H.,Tokyo University of Science | And 2 more authors.
Journal of Artificial Organs | Year: 2013

The hemocompatibility for the recently approved ventricular assist device EVAHEART® was examined through flow visualization with a 300 % scale-up model. The absence of flow separations around the centrifugal vanes indicated that the curvature of the open vanes was suitable. The flow in the vane-shaft clearance was found to effectively produce sufficient shear stresses along the stationary shaft surface. The hemocompatibility was verified for a wide range of flow conditions. © 2012 The Japanese Society for Artificial Organs. Source


Patent
Sun Medical Technology Research Corporation | Date: 2013-08-23

An auxiliary artificial heart pump drive device for driving an auxiliary artificial heart pump includes first and second pump control parts which are arranged in duplexed configuration. Each pump control part controls the auxiliary artificial heart pump by outputting a drive signal to the auxiliary artificial heart pump. Each pump control part has a means which, when a failure is detected in the pump control part, electrically cuts off a path through which the drive signal is outputted to the auxiliary artificial heart pump. According to the present invention, it is possible to provide an auxiliary artificial heart pump drive device and an auxiliary artificial heart system which exhibit high availability even when a serious failure occurs by any chance without duplexing a pump device.


Patent
Sun Medical Technology Research Corporation | Date: 2011-11-29

An artificial heart device includes: a blood pump which assists flow of blood in a heart; a blood pump control part which controls the blood pump; a first data processing part which performs first data processing on at least one data in a first period out of operation data on the blood pump, operation data on a cool sealing unit which circulates lubrication fluid in the blood pump, biological data corresponding to a state of a patient and operation data on a battery; and a TR data storing part which stores data after the first data processing in association with date-and-time data corresponding to date and time at which the data is stored each time the first period elapses, wherein the data stored in the TR data storing part is retrievable.

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