Nazim Shikhverdiev is a cardiac surgeon, professor, Doctor of Medical Sciences, Honored Doctor of the Russian Federation, laureate of the State Prize of the Russian Federation. In his new book “The Debt of the Heart. Cardiac surgeon about the cost of mistakes,” the author shares his professional and life experience, interesting and tragic cases from medical practice, and personal stories of patients. Medical errors are not only a matter of the medical community, but also a big social problem that can affect every patient. Unfortunately, in our country there are no clear legal criteria to determine what is considered a medical error. And this problem must be solved. “The Debt of the Heart” is a book-reflection on the degree of responsibility of a doctor for other people’s lives, about a real calling and a difficult ethical choice. The publishing design is preserved in PDF A4 format.