Development of the NEDO Implantable Ventricular Assist Device with Gyro Centrifugal Pump

Abstract

The Gyro centrifugal pump, PI (permanently implantable) series, is being developed as a totally implantable artificial heart. Our final goal is to establish a "functional TAH," a totally implantable biventricular assist system (BiVAS) with centrifugal pumps. A plastic prototype pump, Gyro PI 601, was evaluated through in vitro and in vivo studies as a single ventricular assist device (VAD). Based upon these results, the pump head material was converted to a titanium alloy, and the actuator was modified. These titanium Gyro pumps, PI 700 series, also were subjected to in vitro and in vivo studies. The Gyro PI 601 and PI 700 series have the same inner dimensions and characteristics, such as the eccentric inlet port, double pivot bearing system, secondary vane, and magnet coupling system; however, the material of the PI 700 is different from the PI 601. The Gyro PI series is driven by the Vienna DC brushless motor actuator. The inlet cannula of the right ventricular assist system (RVAS) specially made for this system consists of 2 parts: a hat-shaped silicone tip biolized with gelatin and an angled wire reinforced tube made of polyvinylchloride. The pump-actuator package was implanted into 8 calves in the preperitoneal space, bypassing from the left ventricle apex to the descending aorta for the left ventricular assist system (LVAS) and bypassing the right ventricle to the main pulmonary artery for the RVAS. According to the PI 601 feasibility protocol, 2 LVAS cases were terminated after 2 weeks, and 1 LVAS case and 1 RVAS were terminated after 1 month. The PI 700 series was implanted into 4 cases: 3 LVAS cases survived for a long term, 2 of them over 200 days (72-283 days), and 1 RVAS case survived for 1 month and was terminated according to the protocol for a short-term antithrombogenic screening and system feasibility study. Regarding power consumption, the plastic pump cases demonstrated from 6.2 to 12.1 W as LVAS and 7.3 W as RVAS, the titanium pump cases showed from 10.4 to 14.2 W as LVAS and 15.8 W as RVAS. All cases exhibited low hemolysis. The renal function and the liver function were maintained normally in all cases throughout these experimental periods. In the 2 RVAS cases, pulmonary function was normally maintained. No calves demonstrated thromboembolic signs or symptoms throughout the experiments except Case 1 with the plastic pump. However, in the plastic pump cases, bilateral renal infarction was suspected in 2 cases during necropsy whereas no abnormal findings were revealed in the titanium pump cases. There were also no blood clots inside the PI 700 series. As for the 601, the explanted pumps demonstrated slight thrombus formations at the top and bottom pivots except in 1 case. The Gyro PI series, especially the PI 700 series, demonstrated superior performance, biocompatibility, antithrombogenicity and low hemolysis. Also, the durability of the actuator was demonstrated. Based on these results, this titanium centrifugal pump is suitable as an implantable LVAS and RVAS. It is likely that the Gyro PI ...

Evaluation of Floating Impeller Phenomena in a Gyro Centrifugal Pump

“…This pump, from the permanently implantable (PI) series, is being developed as a totally implantable artificial heart. 5,6 This pump is composed of the housing, impeller, and actuator. The pump has ultrahigh molecular weight polyethylene female bearings and alumina ceramic male bearings.…”

Performance analysis of ventricular assist devices using finite element flow simulation

“…The shear-slip layer accommodates the rotation of the impeller and surrounding mesh with respect to the housing by deforming and regenerating as frequently as once per time step. The uid is assumed to be Newtonian, with a constant viscosity of 3:354 cP, and a density of 1 g/cm 3 , corresponding to the glycerin solution used in the experiment.…”

“…Axial pumps, such as the DeBakey=NASA pump [2], propel the uid using a miniature turbine, with an axis parallel to the ow direction. Centrifugal pumps, such as the Baylor=Kyocera KP and Baylor PI series [3], use pressure variations produced by rotating vanes to drive the uid from a central inlet towards the peripheral outlet. While the centrifugal pumps are larger than the axial pumps, their rotational speed is typically lower, leading to 'gentler' ow ÿelds and more physiological conditions.…”

Mechanical circulatory support devices for bridge to heart transplantation, bridge to recovery, or destination therapy

“…The system of the Aisin group is the electro-hydraulic TAH, 15 whereas the Baylor group is developing the biventricular bypass system using two pivotbearing supported seal-less centrifugal blood pumps. 16 At Tokyo Medical and Dental University (TMDU), the Department of Artificial Organs was established in April 1999 in the Institute of Biomaterials and Bioengineering to initiate the research and development of artificial organs as an advanced surgical therapeutic method for treating various end-stage diseases. One of them is the artificial heart program, which focuses on the immediate clinical as well as the future needs.…”