CORONARY HEMODYNAMICS OF LEFT MAIN AND BRANCH CORONARY STENOSES - EFFECTS OF REDUCTION IN STENOSIS DIAMETER, STENOSIS LENGTH, AND NUMBER OF STENOSES

Abstract

Although the concept of critical coronary stenosis was studied extensively, there is the agreement on which coronary stenoses consistently decrease coronary blood flow (CBF). In 32 open-chest dogs CBF and aorta-distal coronary pressure gradient were studied at rest and with reactive hyperemia (RH) as stenoses were created in the left coronary artery (LCA) or its major branches-anterior descending (LAD) or circumflex (LCx) arteries. The effects of stenosis location, reduced stenosis diameter, stenosis length and the number of stenoses were studied. Resting CBF and resting distal coronary pressure were decreased by short snare stenoses, which reduced LCA diameter or either major branch > 80%. Lengthening LAD or LCx stenoses 50-60% decreased CBF and increased the pressure gradient. Small increases in pressure gradients occurred but with no change in CBF with multiple stenoses in either the LAD or LCx branch. During peak RH, CBF was decreased by 60% LCA or branch snare stenosis. Peak RH CBF responses decreased further as length of LAD or LCx stenosis increased. Multiple stenoses affected peak RH CBF responses significantly more than a single stenosis of the same total length. Several anatomic variables of coronary stenosis affect the physiological responses of the coronary circulation including reduction in lumen diameter, length of stenosis and number of stenoses in 1 vessel.