Why the study?
How do vessel compliance and changes in hematocrit affect wall shear stress in the coronary arterial tree?
How do vessel compliance and changes in hematocrit affect wall shear stress in the coronary arterial tree?
Vessel compliance determines the nonlinearity of the pressure-flow relation, and acute hematocrit changes significantly alter wall shear stress in epicardial arteries but not in small arterioles.
Acute hematocrit changes may alter epicardial coronary WSS; this animal finding leaves open human relevance and requires clinical validation.
A hemodynamic analysis is implemented in the entire coronary arterial tree of diastolically arrested, vasodilated pig heart that takes into account vessel compliance and blood viscosity in each vessel of a large-scale simulation involving millions of vessels. The feed hematocrit (Hct) is varied at the inlet of the coronary arterial tree, and the Fahraeus-Lindqvist effect and phase separation are considered throughout the vasculature. The major findings are as follows: 1) vessel compliance is the major determinant of nonlinearity of the pressure-flow relation, and 2) changes in Hct influence wall shear stress (WSS) in epicardial coronary arteries more significantly than in transmural and perfusion arterioles because of the Fahraeus-Lindqvist effect. The present study predicts the flow rate as a second-order polynomial function of inlet pressure due to vessel compliance. WSS in epicardial coronary arteries increases >15% with an increase of feed Hct from 45% to 60% and decreases >15% with a decrease of feed Hct from 45% to 30%, whereas WSS in small arterioles is not affected as feed Hct changes in this range. These findings have important implications for acute Hct changes under vasodilated conditions.
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Huo et al. (2009) studied this question.
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