The Journal of Thoracic and Cardiovascular Surgery, Vol 77, 377-388, Copyright © 1979 by The American Association for Thoracic Surgery and The Western Thoracic Surgical Association
The coronary hemodynamics of left main and branch coronary stenoses. The effects of reduction in stenosis diameter, stenosis length, and number of stenoses
RL Feldman, WW Nichols, CJ Pepine, DA Conetta and CR Conti
Although considerable investigation has been devoted to the concept of
"critical" coronary stenosis, there is general lack of agreement on which
coronary stenoses consistently decrease coronary blood flow (CBF). In 32
open-chest dogs we studied CBF and the aorta-distal coronary pressure
gradient 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, reduction in 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 the diameter of the
LCA or either major branch more than 80%. Lengthening 50 to 60% LAD or LCx
stenoses decreased CBF and increased the pressure gradient. There were
small increases in pressure gradients but no change in CBF with multiple
stenoses in either the LAD or LCx branch. During peak RH, CBF was decreased
by a 60% LCA or branch snare stenosis. Peak RH CBF responses decreased
further as length of an LAD or LCx stenosis increased. Multiple stenoses
affected peak RH CBF responses significantly more than a single stenosis of
the same total length. These data indicate that several anatomic variables
of coronary stenosis affect the physiological responses of the coronary
circulation. The variables are (1) reduction in lumen diameter, (2) length
of stenosis, and (3) number of stenoses in one vessel.
