In the spring of 2005, cardiologist Barbara Natterson-Horowitz was called to consult on an unusual patient: an Emperor tamarin at the Los Angeles Zoo. While examining the tiny monkey's sick heart, she learned that wild animals can die of a form of cardiac arrest brought on by extreme emotional stress. It was a syndrome identical to a human condition but one that veterinarians called by a different name-and treated in innovative ways. This remarkable medical parallel launched Natterson-Horowitz