In a compact lab space at Stanford University, Oscar Abilez, MD, trains a microscope on a small collection of cells in a petri dish. A video recorder projects what the microscope sees on a nearby monitor. The cells in the dish pulse rhythmically, about once a second. The cells are cardiomyocytes, which drive the force-producing and pacemaker functions of the human heart. They are programmed to pulse. They will beat this way until they die.