The Effect of Heterogeneity of Capillary Spacing and O₂ Consumption — Blood Flow Mismatching on Myocardial Oxygenation

Abstract

Previously we demonstrated the importance of the heterogeneity of the capillary spacing for the oxygen supply to the myocardial tissue (Turek and Rakusan, 1981). The computed percentage of anoxic myocardial tissue turned out to be a better index of tissue oxygenation than the mean myocardial PO₂. This was especially apparent in situations associated with myocardial hypoxia. The percentage of anoxic myocardial tissue depends not only on the average values of the traditional oxygen determinants included in the Krogh-Erlang equation but also on their variability. In our previous report we analyzed the dependence of myocardial oxygenation on the degree of heterogeneity of capillary spacing for a single value of the mean tissue radius (R) in two situations with respect to blood flow distribution. In the first situation (A) the volume blood flow was perfectly matched to the size of tissue cylinder supplied by a given capillary resulting in uniform end-capillary PO₂. In the second situation (B) identical blood flow was assumed for all capillaries resulting in varying end-capillary PO₂. If uniform oxygen consumption is assumed, then in this situation the O₂ consumption and blood flow must be seriously mismatched. In most cases the real situations obviously lie between these two extreme conditions.