Dr. Michael Gibson was the cardiologist on call Monday at Beth Israel Deaconess Medical Center in Boston when twin bombings struck the city. "These are what are generally called battlefield injuries," Gibson said. "What you see often with explosive devices are these lower extremity injuries. And there are a lot of those in the emergency room, frankly, everything from extensive shrapnel all the way to actually what is called traumatic amputation, where a limb is missing from the victim." He said patients arrived in remarkably stable condition, likely in part due to the injury tent at the finish line of the Boston Marathon, where the blasts occurred.