AJP - Heart and Circulatory Physiology, Vol 245, Issue 6 1054-H1060, Copyright © 1983 by American Physiological Society
Effect of distal coronary pressure on rigid and compliant coronary stenoses
J. S. Schwartz
The effects of changes in distal coronary pressure on the hemodynamics of
rigid and compliant coronary stenoses were studied in anesthetized
open-chest dogs. In dogs with severe compliant circumflex stenoses produced
with an external snare, pressure distal to the stenosis was lowered by
closing a catheter connecting the carotid artery to the distal circumflex
artery and was raised by reopening the catheter. Lowering mean distal
circumflex pressure from 57 +/- 14 to 18 +/- 3 (SE) mmHg (P less than 0.01)
increased stenotic resistance (2.1 +/- 0.7 to 14.1 +/- 7.8 units, P less
than 0.01) and decreased circumflex flow (19 +/- 6 to 6 +/- 4 ml/min, P
less than 0.01). Raising distal pressure (18 +/- 3 to 49 +/- 15 mmHg, P
less than 0.05) decreased stenotic resistance (14.1 +/- 7.8 to 3.7 +/- 0.9
units, P less than 0.05) and increased circumflex flow (6 +/- 4 to 13 +/- 3
ml/min, P less than 0.05). In dogs with rigid stenoses produced with
plastic tubing, a fall in distal pressure significantly increased flow
without a change in stenotic resistance. Therefore, changes in resistance
and flow through compliant coronary stenoses occur in response to changes
in distal pressure. These hemodynamic changes are consistent with passive
collapse and distension of the stenotic segment.
