This project seeks to address a particular unmet need for mechanical circulatory support in children with heart failure. Pediatric heart patients possess several unique features, such as small body size, reduced blood volume, and altered hemodynamic properties. We have sought to account for these features by developing a miniature, low-cost, centrifugal left ventricular assist device for use as an extracorporeal mechanical support system. Our approach will feature a magnetically levitated, and thus friction-less, rotor/stator configuration, which efficiently generates flow, with minimum hemolysis. The major advantages of the current design are its small and relatively simple extracorporeal design, its ability to efficiently regulate pump output over a large range of flow conditions, and its ease of production. This program's overall goal will be to demonstrate that the hemodynamic performance and degree of biocompatibility for the magnetically levitated, centrifugal pump support is appropriate for children with severe heart failure. We contend that the development of a small, inexpensive pump, which requires a minimal priming volume, and which eliminates seals and bearings, is highly desirable. The specific aims of this proposal are as follows: 1) Design and fabricate a pediatric blood pump and motor. 2) Fabricate the system controller, employing optimized flow regulation and power use. 3) Determine pressure-flow characteristics of the ventricular assist device over the range of cardiac output conditions spanning neonates to young children (0.3 to 1.5 L/min). 4) Determine hemolysis levels over the expected range of cardiac outputs. 5) Perform preliminary in vitro endurance testing for the blood pump. 6) Conduct three short-term (< 24 hours) in vivo experiments to demonstrate hemodynamic performance and biocompatibility, and, thus, suitability, of the device for the intended application. We believe that our technology, which provides effective left ventricular assistance with a small, disposable device, may provide needed benefits to the health of children with severe cardiac disease, while not adding significantly to cost of caring for these patients. If we successfully meet the Phase I goals, we will propose in a Phase II program to refine the mechanical design with respect to manufacturing, optimize the ventricular assist control console (with appropriate safety and alarm systems), and expand the in vivo data to include longer-term animal experiments. This would provide a database to support the use of our device for durations consistent with current clinical practice for short-term mechanical support for children.