Evolving trends in mechanical circulatory support: Clinical development of a fully magnetically levitated durable ventricular assist device.

Early generation left ventricular assist devices (LVAD) for treatment of refractory heart failure attempted to mimic the pulsatility of a native heart and were bulky and less durable due to valves within the inflow and outflow pathways. The next disruption came with the introduction of continuous flow pumps characterized by a low-pulse pressure circulation. Since the mechanism of action did not involve displacement of blood, these pumps were much smaller and less noisy in part due to fewer moving parts. Such devices include the HeartMate II axial-flow pathway pump which is implanted thoraco-abdominally and the HVAD, a centrifugal-flow pathway pump which is smaller and is implanted entirely within the thoracic cavity and uses a combination of hydrodynamic and magnetic levitation of the internal rotor. These pumps improved survival compared with the early generation LVADs and in a trial, the HVAD demonstrated non-inferiority compared with the HeartMate II but with an increase in ischemic and hemorrhagic strokes. The HeartMate 3 LVAD is an intrapericardial centrifugal-flow pathway pump with a full magnetically levitated, frictionless rotor with a fixed intrinsic pulse. In a randomized trial, the HeartMate 3 "hybrid" pump was associated with near-elimination of pump thrombosis, a reduction in strokes of any type or severity and lower mucosal bleeding rates. Despite improvements in hemocompatibility, right heart failure and infections contribute to significant morbidity, and devices designed to be internally contained with a wireless power source and physiological flow characteristics are still required despite great strides in the field.