Development of an axial flow blood pump LVAS

Nimbus, Inc., (Rancho Cordova, CA) and the University of Pittsburgh (Pittsburgh, PA) are collaborating to develop an implantable rotary blood pump that can be used as a left ventricular assist system (LVAS). The short-term goal of this project is to show that an LVAS based on this pump can operate safely and reliably during chronic implantations in animals. Work conducted to date includes in vitro testing of hydraulic performance, hemolysis, endurance demonstration, and flow visualization. Results indicate that the pump is capable of generating an output of up to 10 L/min at physiologic pressures. Associated electrical power to drive these pumps is in the range of 6-10 watts. One integrated pump was placed in a mock flow loop and operated continuously at a fixed speed (10,000 rpm), pressure (100 mmHg), and flow rate (6 L/min) for 90 days with no apparent difficulty. In vitro hemolysis test results have consistently ranged between 3-6 g of liberated hemoglobin/day, which is an acceptable range for chronic use. Two in vivo trials of 7 and 14 days were performed using calves, after which tests have been done using sheep as the animal model. Five short-term sheep experiments have been conducted with good results. Future studies will include implantations in sheep of 3 months duration.