Pump thrombosis has been such a well-established shortcoming of left ventricular assist devices (LVADs), that one heart surgeon went so far as to borrow Winston Churchill's phraseology to describe it as "a riddle, wrapped in a mystery, inside an enigma" for the title of his September 2014 article in the Annals of Cardiothoracic Surgery. But St. Jude Medical Inc. may have unraveled that riddle with its Heartmate 3 LVAD system.