Three years ago, surgical resident Bilal Shafi was in the thick of a heart transplant. The patient was a heart attack survivor whose heart function had silently continued to deteriorate, as it does in 30 percent of such cases. When that happens, the heart works harder, expanding to keep up its pumping ability and stretching its walls thin. Shafi had previously helped to install a permanent textile mesh around the patient's heart, an experimental and extreme procedure meant to prevent further dilation and ultimate heart failure. But the patient grew sick enough to require a transplant. During the surgery, Shafi thought, "Why aren't we treating this disease much earlier?"

So he became a fellow in the Stanford Biodesign Innovation program and, over the next three years, developed a biopolymer coating that wraps around the heart and prevents dilation. The coating, which starts out as a liquid, is injected through a catheter immediately following a heart attack. Then it gels, becoming flexible enough to expand with each heartbeat, yet firm enough to support the heart and allow it to heal. After six months, the polymer degrades and the body absorbs it. So far, Shafi has successfully tested it in mice and sheep. He recently returned to his surgical residency at the University of Pennsylvania and has launched a company, COR Innovations, to further develop the technology. --Jennifer Chu