AJP - Heart and Circulatory Physiology, Vol 256, Issue 2 441-H445, Copyright © 1989 by American Physiological Society
Pressure-flow characteristics of coronary collaterals in dogs
K. W. Scheel, H. Mass and S. E. Williams
Department of Physiology, Texas College of Osteopathic Medicine, Fort Worth 76107.
In this study we utilized two methods to investigate the pressure-flow,
P-F, relationship of the coronary collateral vessels in a beating,
blood-perfused, isolated heart preparation. In the first method (free-flow
method), 12 dog hearts were perfused at pressures ranging from 100 to 0
mmHg, whereas the retrograde flow (index of collateral flow) was measured
on the circumflex coronary artery, LCA, against atmospheric pressure, first
during autoregulation and then after maximum vasodilation. In the second
method (back-pressure method), the back pressure to retrograde flow was
varied from 0 to 100 mmHg, whereas the perfusion pressure to the remaining
vessels was maintained constant at 100 mmHg. This procedure was performed
on four hearts with and without embolization of the LCA by 25-microns
spheres. The free-flow method demonstrated a linear P-F relationship with
an average correlation coefficient, r, of 0.98. The pressure intercept was
1.7 +/- 1.2 mmHg. The back-pressure method yielded a relationship that was
more curvilinear with an average pressure intercept of 13 mmHg without
embolization and 38 mmHg with embolization. An analog of the coronary and
collateral circulation was used to illustrate that, in the back-pressure
method, changes in the coronary resistance at low pressures contributed to
the nonlinearity of the collateral P-F characteristics and that the network
formed between the collateral and coronary resistances was responsible for
the higher pressure intercept value.
