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We developed a small, lightweight, low-cost implantable ventricular assist device (VAD) for use in smaller Japanese subjects. The major advantage of this pump is the simplicity of its fabrication. Most parts of the pump were shaped from a transparent acrylic block by a turning process, and the diaphragm was made from a silicon sheet. Since this method of construction did not require any complex processes, we could manufacture many pumps of various shapes. We determined the most efficient shape for the Ebacor VAD using the flow visualization technique. The pump showed an output above 6 liters/min under a driving pressure of 300/-100 mmHg. The pump performance of current VADs is superior to that of the Ebacor VAD, because these pumps are larger. Since the Ebacor VAD is small in size, it can be driven by the driving system of a normal IABP control unit, which many hospitals already have in place. During a 30day continuous driving performance test of this pump, no problems like performance decrements or water and air leakage were observed.

We have developed a practical, low-cost ventricular assist device (VAD) comprising a newly designed blood chamber with a silicone lenticular sac and two silicone tri-leaflet valves (STV), made en bloc. This new VAD is seamless, can be made cost-effectively and assembled with the blood chamber and valve as one body. This novel design should reduce the incident of thrombus formation because of the absence of a junction at the connecting ring and because of the use of flexible silicone materials which have both antithrombogenecity and biocompatibility. In in vitro hemodynamics testing, a batch of 3 consecutively manufactured V ADs with STV s underwent hydrodynamic functional testing. These showed less regurgitation, a lower value of water hammer phenomenon, and a slightly greater pressure gradient across the valves than a mechanical valve (MV) [Björk-Shiley monostrut valve]. The flow and pulsatile efficiency were adequate and similar to that of a VAD with MVs. In in vitro durability and hemolysis tests, a V AD with STV functioned well for 54 days and showed similar hemolytic profiles to a V AD with MVs. In an in vivo acute experiment using an adult sheep, our device was promblem-free providing sufficient output as a left ventricular assist device (LVAD). Although it will be necessary to decrease the pressure gradient across this STV in the future, our device showed efficient performance as a practical and cost-effective V AD for short term use., This work was supported in part by the Tsuchiya Foundation and by a Research Grant for Cardiovascular Diseases (7A-1) from the Ministry of Health and Welfare, Japan