AJP - Heart and Circulatory Physiology, Vol 249, Issue 5 981-H988, Copyright © 1985 by American Physiological Society
Effect of arteriolar dilation on coronary artery diameter distal to coronary stenoses
J. S. Schwartz and R. J. Bache
Previous studies have suggested that worsening hemodynamic severity of
coronary stenoses in response to distal arteriolar dilation may be related
to dilation of the normal epicardial artery adjacent to the stenosis
resulting in increasing percent stenosis. To test this hypothesis we used
sonomicrometry to continuously measure external circumflex coronary artery
diameter distal to snare stenoses of varying severity in 19 open-chest dogs
and 5 awake, chronically instrumented dogs. Arteriolar dilation produced by
release of a transient coronary occlusion or by intracoronary injection of
adenosine caused a decrease in circumflex coronary diameter distal to the
stenosis. Regression analysis showed that circumflex diameter and pressure
distal to the stenosis were directly related (mean r: transient occlusion,
0.86 +/- 0.04; adenosine, 0.97 +/- 0.01). The close relationship between
pressure and diameter suggests that the decrease in diameter in response to
arteriolar dilation was a passive effect. Passive coronary narrowing distal
to a stenosis suggests that a similar effect may occur within a compliant
stenosis, thus partly explaining the increase in severity of compliant
stenoses in response to arteriolar dilation.
