Submitted on August 2, 2008
Revised on May 26, 2009
Accepted on June 12, 2009
Effect of Compliance and Hematocrit on Wall Shear Stress in a Model of Entire Coronary Arterial Tree
Yunlong Huo1 and Ghassan S. Kassab1*
1 Indiana University Purdue University Indianapolis
* To whom correspondence should be addressed. E-mail: gkassab{at}iupui.edu.
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 over millions of vessels. The feed hematocrit (Hct) is varied at the inlet of coronary arterial tree and the Fahraeus-Lindqvist effect and phase separation are considered throughout the vasculature. The major findings are: 1) vessel compliance is the major determinant of nonlinearity of pressure-flow relation, and 2) Hct changes influence wall shear stress (WSS) in epicardial coronary arteries more significantly than 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. The 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% while 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.
