Spatial Distribution of Coronary Capillaries: A-V Segment Staggering

Abstract

The modelling of oxygen transport to tissue necessitates a concerted effort in linking structural and functional data. In our laboratory, we are interested in the geometrical distribution of coronary capillaries. Traditionally, capillary supply has been characterized only by measures of capillary density, from which it is possible to calculate average inter-capillary distance (ICD). The deficiency in such a calculation is the assumption of a uniform distribution of capillaries. The heterogeneity of inter-capillary spacing is clearly an important factor in myocardial oxygenation, over and above average ICD. Methods for assessing the heterogeneity of capillary spacing, and it’s effect on myocardial oxygenation have been recently analyzed (Rakusan and Turek, 1985 and Turek et. al., 1987). Another important parameter for modelling oxygen transport is the knowledge of the direction of blood flow in adjacent capillaries. Our recent application of coloured microspheres, for the analysis of myocardial flow pattern, revealed a predominance of concurrent flow in neighboring capillaries (Reeves and Rakusan, 1987). Nonetheless, a uniformity in flow direction does not ensure that the spatial position and P02 values of neighboring capillaries are synchronous. One may envision a situation where the transverse arteriole furnishes capillaries at staggered levels in the tissue.