An emotion is much more than a state of feeling. Intense fear, grief, anger or even joy begins as a sort of cortical storm which involves an energetic disturbance of the entire body. Such a disturbance may be a very serious or even fatal complication of a pre-existing disease. Thus John Hunter, suffering from chronic heart disease and liable, when excited, to attacks of angina, said that his life was at the mercy of any scoundrel who should make him angry. While to all appearance in his usual health, he was debating a question of personal importance to himself at a board meeting at St. George's Hospital. One of his opposing colleagues flatly contradicted him, a cardiac attack came on, he instantly ceased speaking, went into the next room and fell dead in the arms of a friend.
Not many cases are so dramatic and angina is fortunately not common
PERSHING HT. THE TREATMENT OF EMOTIONAL DISTURBANCES.. JAMA. 1904;XLII(5):300-304. doi:10.1001/jama.1904.92490500020001g