DEVELOPMENT OF THE NIMBUS PITTSBURGH AXIAL-FLOW LEFT-VENTRICULAR ASSIST SYSTEM/

Nimbus, Inc. and the University of Pittsburgh's School of Medicine hav e been collaborators developing rotary blood pump technology since 199 2. Currently, a major focus is on an implantable left ventricular assi st system (LVAS) that utilizes an electric powered axial flow blood pu mp. In addition to the blood pump, a major development item is the ele ctronic controller and the control algorithm for modulating the pump s peed in response to varying physiologic demands. Methods being used in developing the axial flow LVAS include the use of computational fluid dynamic modeling of the interior flow field of the pump, flow visuali zation of the flow field using laser based imaging, and computer simul ation of blood pump-physiological interactions as well as an extensive in vivo test program. Results to date include successful in vivo test s of blood pumps with nonlubricated bearings and demonstrations of aut o speed control using electrical current as the observable parameter.