For decades, engineers have attempted to design implantable artificial hearts and LVADs (left ventricular assist devices), but with only mixed success. The same devices that save many of those suffering from life-threatening heart disease-by assisting their heart until a suitable donor organ becomes available-can damage the blood it pumps, causing a 15% incidence of strokes in patients. And each LVAD failure means another perilous surgery for the patient. Fortunately, two devices that minimize these potentially harmful side effects have made the breakthrough to animal testing and may become clinically available in the next few years. Both replace standard blood-lubricated bearings with magnetic bearings that promise to improve pump reliability, extend operating life, and minimize blood damage. Magnetically levitated propellers distinguish these from clinically available devices. Because conventional bearings suffer from friction and wear--and opportunities for clotting and infection-- these maglev designs suspend the rotor in a magnetic field. Moreover, these maglev pumps are intended as permanent alternatives to a transplant--an important attribute given the shortage of donor organs.