The promise of integrating magnetic bearing systems into mechanical circulatory assist devices has been acknowledged for some time and includes patents that have since expired. Several decades later, many of the devices in use incorporate some aspects of magnetic bearings and a few fully magnetically suspended pumps exist, but they are still far from ubiquitous in clinical use. The most commonly implanted pumps in 2015 remain mechanically suspended rotary type devices, such as the HeartMate II. This is likely a reflection of both increased size and decreased reliability that accompany magnetic bearing system, both resulting from additional components described in this monograph. The slow adoption of this technology is also the results of the complex regulatory and scientific environment, where the true performance of mechanical assist devices is often not known until used in humans and the costs of developing a device to the point of clinical trials is enormous.
