[The concept of "dynamic" coronary artery stenosis].

The present understanding of the pathogenesis of myocardial ischemia is primarily based on the concept of either a high-grade "fixed" coronary artery obstruction or a spastic vasoconstriction of an epicardial coronary artery. Both these mechanisms do not sufficiently explain the variable clinical syndromes of angina pectoris, particularly not the variation in anginal threshold experienced by many patients. Therefore, the concept of a variable vasoconstriction ("functional component") superimposed on an atherosclerotic lesion ("organic component") constitutes a plausible hypothesis connecting both pathogenetic mechanisms. The pathophysiological basis for this concept of "dynamic" changes in the degree of coronary artery stenosis, the clinical relevance and the therapeutical consequences are discussed.