Effect of Coronary Perfusion Pressure or Coronary Flow on Oxygen Usage of the Myocardium

H A major pastime in which most cardiovascular physiologists have engaged at one time oi" another is the search for the primary determinant of the oxygen usage by an organ. The heart has been a favorite organ for this endeavor. One of the early studies related oxygen usage to the diastolic volume of the ventricle; one of the more recent studies related it to the area under the systolic portion of the aortic pressure curve. In addition, attempts (with varying degrees of success) have been made to relate the oxygen usage per heart beat of the left myocardium to its stroke work, the mean arterial blood pressure, left A'entricular filling pressure or mean atrial pressure, tension within the myocardial wall, oxj-gen tension within the myocardium, action of local metabolites and vasodilating substances, and to other parameters. The occasion for this editorial and four associated manuscripts from the laboratories of Braumvald, Katz, and Sarnoff, is the consideration of the possibility of another controlling influence on myocardial oxygen usage. The view has long been held that change in coronary perfusion pressure cannot of itself alter myoeardial metabolism. In 1957, however, experiments were reported