MORPHOMETRY OF PIG CORONARY VENOUS SYSTEM

This is a third part of tripartite morphometric data of the pig corona ry blood vessels, giving a complete quantitative description of the ar terial tree [Kassab et al., Am. J. Physiol. 265 (Heart Circ. Physiol. 34): H350-H365, 1993], capillary network [Kassab and Fung, Am. J. Phys iol. 267 (Heart Circ. Physiol. 36): H319-H325, 1994], and venous tree (this article). Together they provide the quantative anatomic foundati on for coronary hemodnamics. The coronary venules have a unique morpho logy. Unlike coronary arterioles, which have cylindrical cross section s and a fairly constant diameter in each segment, the venules have app roximately elliptical cross sections, are usually wavy in the longitud inal direction, and often converge like fingers to a hand. Measurement s were made with the silicone elastomer casting method on five pig hea rts. Data on smaller vessels were obtained from histological specimens by optical sectioning. Data on larger vessels were obtained from vasc ular casts. Arcading veins and anastomoses on the epicardial surface h ave a unique topology. Data on the number of vessels in each order, th e major and minor axes, length, connectivity matrix, and the fractions of the vessels of a given order connected in series in all orders of vessels of the sinusal and thebesian veins are presented. It is shown that of the blood in the coronary blood vessels of a pig heart 27.4% i s in the arteries (> 200 mu m), 37.1% is in veins (> 200 mu m), and 35 .5% is in microcirculation (< 200 mu m), of which 89.4% is in the capi llaries.