This episode was written by a guest contributor, Simar Bajaj, a student of the History of Science at Harvard University. In it, we cover the story of the mitral valve, from its earliest descriptions, to the discovery of its function and pathology, and of course, the evolution of the surgical treatment of both stenosis and regurgitation. In addition to meeting the surgeon innovators, we will of course take some detours, looking at how percussion became a part of the physical exam, reviewing the origins of the term hyperkalemia, cover some surgical rivalries, and lots more!