More than 4,000 people in the U.S. are waiting for a new heart, that’s according to the organization Donate Life America. Anxiety, fear and frustration are some of the emotions people go through while waiting for a lifesaving organ. Dr. Lisa LeMond, a Mayo Clinic cardiologist, says perfusion technology, sometimes called “heart in a box,” is giving hope to transplant patients. Watch the video from the Mayo Clinic.