Current research and problems of the coronary circulation.

H EART disease, especially coronary artery disease, continues to be one of the foremost problems in medicine today. A good estimate is that about one third of those who die from heart disease in the United States do so from a primary coronary insufficiency related to atherosclerosis as the dominant factor, one third die from primary coronary insufficiency associated with cardiac hypertrophy and increased cardiac work arising from valvular lesions and increased blood pressure, and one third as a result of a primary myocardial insufficiency. Of the available methods of study, none gives detailed or accurate information regarding the coronary system in the normal or diseased staet. Such studies require precise methodology that is difficult to apply to the heart because of its gross inaccessibility. For this reason various types of instrumentation are introduced in order to obtain hemodynamic and metabolic data, but such data are often of doubtful value. Accordingly, advances in the field of the coronary circulation are based on a combination of difficult precision instrumentation applied directly to the exposed or isolated heart and of questionable indirect methodology applied to the heart in the intact state. By synthesis of available experimental facts, however, considerable progress has been made toward the solution of certain problems in this field. Metabolic Patterns in the Heart. Since the ability of the heart to do work depends basically on its biochemical activity leading to muscular contraction, any definitive analysis