For nearly two years, Dick Cheney lacked a detectable pulse. In the summer of 2010, Cheney was facing end-stage heart failure. He had suffered his first heart attack in 1978, his second and third in the 1980s, and his fourth in November 2000, presumably when the strain of stealing a presidential election proved too much to bear. Despite these valiant efforts, Cheney’s heart was unable to kill him off. Not even a fifth heart attack, in February 2010, when Cheney’s two terms as “vice” president had finally come to an end, could finish the job. That’s when Cheney’s doctors decided that his defibrillator was no longer sufficient, and five months later, they outfitted him with something called a left ventricular assist device, or LVAD. Though designed to compensate for the diminished capabilities of Cheney’s heart by facilitating the circulation of his blood, the LVAD did not pump blood like a real heart does. Instead of discrete beats, the LVAD produced an even, continuous flow, like a river.…