The Fontan procedure for univentricular heart defects creates a unique circulation where all pulmonary blood flow is passively supplied directly from systemic veins. Computational simulations, aimed at optimizing the surgery, have assumed blood to be a Newtonian fluid without evaluating the potential error introduced by this assumption. We compared flow behavior between a non-Newtonian blood analog (0.04% xanthan gum) and a control Newtonian fluid (45% glycerol) in a simplified model of the Fontan circulation. Particle image velocimetry was used to examine flow behavior at two different cardiac outputs and two caval blood flow distributions. Pressure and flow rates were measured at each inlet and outlet. Velocity, shear strain, and shear stress maps were derived from velocity data. Power loss was calculated from pressure, flow, and velocity data. Power loss was increased in all test conditions with xanthan gum vs. glycerol (mean 10 ± 2.9% vs. 5.6 ± 1.3%, $p=0.032$). Pulmonary blood flow distribution differed in all conditions, more so at low cardiac output. Caval blood flow mixing patterns and shear stress were also qualitatively different between the solutions in all conditions. We conclude that assuming blood to be a Newtonian fluid introduces considerable error into simulations of the Fontan circulation, where low-shear flow predominates.

用于单心室心脏缺损的Fontan手术产生了独特的循环，其中所有肺血流直接从全身静脉被动供应。旨在优化手术的计算模拟已将血液假定为牛顿流体，而未评估该假设所引入的潜在误差。我们在Fontan循环的简化模型中比较了非牛顿血液类似物（0.04％黄原胶）和对照牛顿流体（45％甘油）之间的流动行为。粒子图像测速仪用于检查两个不同心输出量和两个腔血流量分布的流动行为。在每个入口和出口测量压力和流速。速度，剪切应变和剪切应力图是从速度数据中得出的。根据压力，流量和速度数据计算功率损耗。$p=0。032$）。在所有情况下，肺血流量的分布都不同，在低心排量时更是如此。在所有条件下，溶液之间的骑兵血流混合模式和切应力在质量上也有所不同。我们得出的结论是，假设血液是牛顿流体，那么在低剪切力流动占主导地位的Fontan循环模拟中会引入相当大的误差。