The an initial concept of disease of the myocardium as well as the subsequent changes in concepts have been closely related to the availability of diagnostic and research tools, to periodic advancements in general scientific knowledge, and to the development of technics whereby this knowledge could be applied to medicine. The beginning of the 19th century has been selected as the starting point of this discussion as concepts existing prior to that period were in most part based on theory and fantasy. Period 1800 to 1900 In the year 1800, all the physician had to aid him in his recognition and study of heart disease besides his eyes and hands was the crude stethoscope as introduced by Laennac, and simple light microscopy. Bacteriology and immunology were nonexistent, and knowledge of biochemistry and physiology were very meager. The prevailing clinical concept of heart disease was that there were two basic types