When Harry Selker was working as a cardiologist in the 1970s, clot-busting drugs were showing great promise against heart attacks. But their life-saving properties were very time sensitive. "If you give it within the first hour it has a 47 percent reduction of mortality; if you wait another hour, it has a 28 percent reduction; another hour, 23 percent. And people were taking about 90 minutes to make that decision," he recalls. "So they were losing the opportunity to save patients' lives."