New concepts regarding constriction within a stenosis Influence of intraluminal pressure changes

Morphologic and clinical studies clearly show that most human coronary lesions exhibit vasomotion. Variable ischemic thresholds, ischemia unrelated to workload, and variant angina further prove the presence of vasoconstriction in coronary artery disease. While vasoconstriction is important in the presentation of coronary artery disease, the unique type of contraction present in an arterial stenosis has been only recently examined. In normal large conduit arteries, the afterload opposing smooth muscle contraction is the intraluminal pressure, which remains relatively constant. In stenotic arteries, as the artery constricts, the pressure (or afterload) opposing smooth muscle shortening decreases, leading to exaggerated constriction and augmented arterial narrowing. Physiologically, this implies that a unique type of contraction ("heterotonic") occurs within an arterial stenosis. Clinically, this type of contraction might explain the exaggerated shortening observed within an arterial stenosis. It also suggests that stenotic pressure is an important variable in the pathophysiology and potential treatment of angina pectoris.