Cheng Christopher P, Herfkens Robert J, Taylor Charles A
Department of Mechanical Engineering, Stanford University, Stanford, California 94305-3030, USA.
Am J Physiol Heart Circ Physiol. 2003 Apr;284(4):H1161-7. doi: 10.1152/ajpheart.00641.2002. Epub 2002 Dec 5.
Compared with the abdominal aorta, the hemodynamic environment in the inferior vena cava (IVC) is not well described. With the use of cine phase-contrast magnetic resonance imaging (MRI) and a custom MRI-compatible cycle in an open magnet, we quantified mean blood flow rate, wall shear stress, and cross-sectional lumen area in 11 young normal subjects at the supraceliac and infrarenal levels of the aorta and IVC at rest and during dynamic cycling exercise. Similar to the aorta, the IVC experienced significant increases in blood flow and wall shear stress as a result of exercise, with greater increases in the infrarenal level compared with the supraceliac level. At the infrarenal level during resting conditions, the IVC experienced higher mean flow rate than the aorta (1.2 +/- 0.5 vs. 0.9 +/- 0.4 l/min, P < 0.01) and higher mean wall shear stress than the aorta (2.0 +/- 0.6 vs. 1.3 +/- 0.6 dyn/cm(2), P < 0.005). During exercise, wall shear stress remained higher in the IVC compared with the aorta, although not significantly. It was also observed that, whereas the aorta tapers inferiorly, the IVC tapers superiorly from the infrarenal to the supraceliac location. The hemodynamic and anatomic data of the IVC acquired in this study add to our understanding of the venous circulation and may be useful in a clinical setting.
与腹主动脉相比，下腔静脉（IVC）内的血流动力学环境尚未得到充分描述。我们使用电影相位对比磁共振成像（MRI）以及开放式磁体中定制的与MRI兼容的循环装置，对11名年轻正常受试者在静息状态和动态骑行运动时，腹主动脉和下腔静脉的腹腔干上方和肾下水平的平均血流速度、壁面剪应力和横截面积进行了量化。与主动脉相似，运动导致下腔静脉的血流和壁面剪应力显著增加，肾下水平的增加幅度大于腹腔干上方水平。在静息状态下的肾下水平，下腔静脉的平均流速高于主动脉（1.2±0.5对0.9±0.4升/分钟，P<0.01），平均壁面剪应力也高于主动脉（2.0±0.6对1.3±0.6达因/平方厘米，P<0.005）。运动期间，下腔静脉的壁面剪应力仍高于主动脉，尽管差异不显著。还观察到，主动脉向下逐渐变细，而下腔静脉从肾下位置到腹腔干上方位置向上逐渐变细。本研究中获取的下腔静脉血流动力学和解剖学数据增进了我们对静脉循环的理解，可能在临床环境中有用。
