[Coronary vasomotion in coronary heart disease--significance of epicardial and microcirculatory vessels for myocardial perfusion].

The most important function of the coronary vasculature is the effective regulation of coronary blood flow according to the metabolic needs of the myocardium. Under physiological conditions, coronary blood flow is regulated by a balance of vasoconstricting and -dilating components which can be differentiated with regard to the site (macro- vs. microcirculation), compartment (endothelium vs. vascular smooth muscle), and mechanism of action (receptor dependent vs. independent). This balance includes on the one hand the ability of the coronary circulation to maintain a relatively constant blood flow at any given oxygen demand irrespective of perfusion pressure (coronary autoregulation). On the other hand, coronary blood flow can be increased rapidly and effectively several-fold when myocardial oxygen demand increases. Previous investigations have demonstrated that the coronary endothelium plays a key role in the development of arteriosclerotic vascular lesions. In the time course of arteriosclerosis, functional alterations in endothelium dependent vasodilatation alterations are already present before angiographically demonstrable morphologic lesions. In the present manuscript, the diagnostic methods used to assess clinically the coronary macro- and microcirculation with regard to endothelium and smooth muscle dependent vasomotion are reviewed. In addition, present pharmacotherapeutic strategies to improve myocardial perfusion in coronary artery disease are discussed.