Noninvasive measurements of myocardial oxygen consumption--can we do better?

Normal cardiac performance reflects the interdependence between myocardial mechanical function, myocardial oxygen consumption (MVO2), and blood flow. Indeed, physiologic processes directly associated with systolic function (e.g., wall stress, shortening, heart rate, contractility) are major determinants of MVO2. Conversely, when myocardial blood flow is interrupted, there is rapid cessation of MVO2 and systolic function. The linkage between myocardial blood flow and mechanical function provided by MVO2 reflects primarily the oxidation of substrates for myocardial energy production. Consequently, because of the central role of MVO2 in cardiac physiology, the noninvasive quantification of MVO2 is crucially important in both cardiovascular investigation and clinical cardiology.