We hear stories about young, apparently healthy athletes who suddenly die after an intense performance. What’s going on? For some, about one in five thousand, a heart disorder known as ARVD is to blame. It’s a genetic condition that affects heart tissue, causing fat and scar fibers to build up, interfere with electrical impulses, and disrupt the heart’s rhythm.Hopkins cardiologist Dr. Hugh Calkins says treatment includes this sobering advice exercising: no endurance sports, no competitive sports. And we hear from Preston Haugh, who thought soccer might be his path to the Olympics, until a fainting episode altered his dream.