Xie J P, Liu S Q, Yang R F, Fung Y C
Department of AMES-Bioengineering, University of California, San Diego, La Jolla 92093.
J Biomech Eng. 1991 Feb;113(1):36-41. doi: 10.1115/1.2894083.
The zero-stress state of a vein is, like that of an artery, not a closed cylindrical tube, but is a series of segments whose cross-sections are open sectors. An opening angle of each sector is defined as the angle subtended between two radii joining the midpoint of the inner wall to the tips of the inner wall. Data on the opening angles (mean +/- standard deviation) of the veins and vena cava of the rat are presented. For the superior vena cava and subclavian, jugular, facial, renal, common iliac, saphenous, and plantar veins, the opening angle varies in the range of 25 to 75 deg. The inferior vena cava (below the heart), however, has noncircular, nonaxisymmetric cross-sections, a curved axis, and a rapid longitudinal variation of its "diameter"; its zero-stress state is not circular sectors; but the opening angle is still a useful characterization. The mean opening angle of the interior vena cava varies in the range of 40 to 150 deg in the thoracic portion, and 75 to 130 deg in the abdominal portion, with the larger values occurring about the middle of each portion. There are considerable length, diameter reductions, and wall thickening of the vena cava from the homeostatic state to the no-load state in vitro. Physically, the zero-stress state is the basis of the stress analysis of blood vessels. The change of opening angle is a convenient parameter to characterize any nonuniform remodeling of the vessel wall due to changes in physical stress or chemical environment.(ABSTRACT TRUNCATED AT 250 WORDS)
静脉的零应力状态与动脉一样，并非是一个封闭的圆柱形管道，而是一系列横截面为开放扇形的节段。每个扇形的开口角度定义为连接内壁中点与内壁尖端的两条半径之间的夹角。文中给出了大鼠静脉和腔静脉开口角度（平均值±标准差）的数据。对于上腔静脉、锁骨下静脉、颈静脉、面静脉、肾静脉、髂总静脉、大隐静脉和足底静脉，开口角度在25至75度范围内变化。然而，下腔静脉（心脏下方）具有非圆形、非轴对称的横截面、弯曲的轴线以及其“直径”的快速纵向变化；其零应力状态并非圆形扇形；但开口角度仍是一个有用的表征参数。胸段下腔静脉的平均开口角度在40至150度范围内变化，腹段在75至130度范围内变化，较大值出现在各段的中部左右。从体内稳态状态到体外无负荷状态，腔静脉会出现显著的长度缩短、直径减小和管壁增厚。从物理角度来看，零应力状态是血管应力分析的基础。开口角度的变化是一个方便的参数，可用于表征由于物理应力或化学环境变化导致的血管壁任何不均匀重塑。（摘要截断于250字）
