Resistive vessel function in coronary artery disease.

Traditionally, the coronary circulation was divided into two arterial compartments: the conduit and the resistive vessels. It has become apparent that there is substantial heterogeneity in resistive vessels with respect to the regulation of coronary flow, which is modified by the perfusion pressure, flow, myocardial metabolism, and ventricular wall tension. Early in the atherosclerotic process, the ability of the coronary resistive vessels to vasodilate maximally under physiological or pharmacological stress is impaired,' often in the presence of coronary risk factors and before the development of angiographically apparent disease." There is also some evidence showing that myocardial ischaemia may be caused or exacerbated by an inappropriate vasoconstriction of resistive vessels.45