Thrombosis and failure of a HeartMate II device in the absence of alarms.

Next-generation left ventricular assist devices such as the HeartMate II (Thoratec Corporation, Pleasanton, CA) have significantly improved patient outcomes. In particular, the incidence of thromboembolic events appears to be significantly reduced. Pump thrombosis has occurred, however, and is well reported in the literature. The thromboses reported with next-generation devices have generally been partial thromboses associated with significant abnormalities in the system performance data as displayed on the system monitor. We describe a case of complete thrombosis of a HeartMate II axial-flow pump resulting in cardiac arrest but in the absence of alarms or significant aberrations in the performance data.