Contribution of Nuclear Cardiology to the Diagnosis of the Various Stages of Coronary Artery Disease

Abstract

Nuclear cardiology claims to be able to contribute information on various aspects of myocardial diseases. The complete description of the myocardial state includes the perfusion, metabolism, and function of the myocardium. The immediate cause of myocardial disease is insufficient oxygen delivery, whereaus substrate delivery is not that important. The sensitivity of the system to very small perfusion defects results from the high extraction rate of oxygen, which in the myocardium reaches 75%; in normal muscle the extraction rate is only 25%. This is a critical point, because oxygen delivery cannot be effectively improved by an increase in extraction rate. Improvement is possible only by increasing the myocardial blood flow. Thus far, perfusion imaging is of paramount importance for detection of oxygen deficiency in the myocardium. Subsequent metabolic disorders, e.g., anaerobic glycolysis, call for their respective metabolic radionuclide indicators [1]. Finally, the metabolic failure results in functional abnormalities of the myocardium, which implies motion abnormalities (hypokinesis, dyskinesis), which can be visualized by radionuclide ventriculography.