Low bearing wear in explanted HeartMate II left ventricular assist devices after chronic clinical support.

The primary objective of this study was to evaluate bearing wear during clinical use of the HeartMate II (HMII) left ventricular assist device. Bearings obtained from HMII pumps explanted after clinical use in the Destination Therapy and Bridge to Transplantation clinical trials were analyzed for wear using surface profilometry. Geometric profile variations measured on the inlet bearing ball were used to calculate the wear.

Controller for an Axial Flow Blood Pump.

A rotary blood pump inherently provides only one noninvasive "observable'" parameter (motor current) and allows for only one "controllable" parameter (pump speed). To maintain the systemic circulation properly, the pump speed must be controlled to sustain appropriate outlet Hows and perfusion pressure while preventing pulmonary damage caused by extremes in preload. Steady-state data were collected at repeated intervals during chronic trials of the Nimbus AxiPump (Nimbus, Inc.