Total and shunting circulation in human central hemodynamics

Abstract

The goal of the study was to develop a method for the separate measurement of capillary and metarteriolar circulation. Data on the cardiovascular system of 301 male patients (1–49 years of age) and 344 female patients (1–50 years of age) with a diagnosis of functional murmur were used. In the process of heart and major vessel diagnostic catheterization, the diagnosis of heart defect was excluded. The cardiac output (Q) was estimated. The calculated oxygen consumption was converted using the Hüfner’s coefficient to the equivalent quantity of hemoglobin (Hb) delivering this oxygen into exchange capillaries. The Hb content per milliliter of blood is known; therefore, by dividing the total quantity of Hb that passed through capillaries by its content per milliliter of blood, one can obtain the blood volume (in milliliters) that passed through the capillary bed (Q _cap). A shunt in the microvasculature was found as the difference between Q and Q _cap). Thus, there exist in the microvascular module two parallel bloodstreams: a slow one, which goes through true capillaries, where the exchange happens, and a fast shunting stream through metarterioles, direct channels, and arteriolevenous anastomoses. The latter not only takes part in the tissue thermal exchange, but are also channels that ensure the free transfer of white blood cells through the microcirculatory module, especially of those whose characteristic sizes exceed the diameter of the metabolic capillaries. The contribution of these two parallel streams in the microcirculatory module into Q is different. According to other results of this study, the slow capillary stream makes up approximately 20%, whereas the fast shunting bloodstream, 80% of Q.