Distribution of the geometric parameters of human aortic bifurcations.

Abstract

I n a recent study using human arterial casts, Friedman et al. 1 identified four geometric features of aortic bifurcations whose variation from one individual to another resulted in significant variability in the hemodynamic shear stress at particular sites on the vessel wall. The four specific geometric features were:1. A large angle of one or both daughters with the aortic axis; 2. A flow divider that did not lie on the axis of the terminal aorta, called flow divider offset; 3. An iliac artery that made a large angle with the aortic axis while the other one closely followed that axis; 4. A gentle intrusion of the arterial wall into the flow as the flow divider was approached.The first three of these characteristics resulted experimentally in regions of inordinately low shear. In a related investigation, we demonstrated a negative correlation between interfacial shear rate and intimal thickness. 2 In view of the association between intimal thickening and arterial pathology, this paper focuses on branch angle, angular asymmetry, and flow divider offset. The possible importance of branch angle has been recognized and discussed in earlier literature. Saltissi et al. 3 and Sharp et al. 4 related arterial branch angle to the incidence of occlusive disease. Hutchins et al., 5 Raso et al., 6 and Lee et al. 7 have published anatomical studies of arterial features including branch angle. Other researchers have studied the various fluid dynamic effects of branching because of their presumed importance to atherogenesis. 8 " 14 On the other hand, neither flow-divider offset nor angular asymmetry have received similar attention. The purpose of this paper is to call attention to the variability in these other parmeters and to present their distributions and those of branch angle among human aortic bifurcations.We carried out a retrospective study to determine objectively the distributions of angles and offsets within a collection of 70 aortic bifurcations. We created computer routines that calculated these quantities using as input the wall contours obtained from frontal-plane radiographs of these arterial segments. MethodsThe aortic bifurcations were obtained at autopsy. Of the 70 specimens, 42 were from women and 28 were from men. The mean age of the women was 57.3 ± 14.8 years (SD), with a range of 21 to 80 years. The mean age of the men was 57.3 ± 1 8 . 1 years, with a range of 16 to 81 years. The arteries were cannulated and perfused with a 4% formaldehyde solution that was maintained under a hydrostatic pressure head equivalent to the blood pressure recorded during life. The pressure was maintained

Differential growth patterns of the abdominal aorta and vertebrae during childhood

“…The mean AB angle of 48.4° (24.6° to 70.8°) in our pediatric sample is similar to the mean AB angle reported in an adult population by Moussallem et al () of 47.4° (17° to 100°). Interestingly, the vertebral level of the AB was a significant predictor of the AB angle where patients with more proximal AB levels had more acute AB angles ( P < 0.001), which supports the findings of a small number of adult studies (Bargeron et al, ). This is not surprising as when the aorta terminates more proximally, a more acute AB angle is required to provide the most direct route to the pelvis and lower limb.…”

“…The geometry of blood vessels regulates flow dynamics and may play a critical role in the pathogenesis of vascular disease such as atherosclerosis, aneurysm formation, or dissection (Bargeron et al, ). We report for the first time in children a significant correlation of the AB angle with age independent of sex with older subadults demonstrating smaller angles.…”

Relation of vessel wall shear stress to atherosclerosis progression in human coronary arteries.

“…The role of mechanical forces in human coronary atherosclerosis progression has been previously investigated by the use of casts of vascular structures such as the aorta or carotid circulations. 12 - 32 The purpose of this study was to determine by means of quantitative angiography if shear stress at multiple points along the length of the human coronary artery could be related to the rate of atherosclerosis progression over time in vivo.…”

Methods for Three-Dimensional Geometric Characterization of the Arterial Vasculature

“…23,41 More recently quantitative analyses of arterial geometries have also been performed to aid endovascular device design 19,58 and endograft sizing. 57 Hence, investigations relating to characterization of arterial branching and morphology have been focused on regions predisposed to atherosclerotic disease, in particular the aortic arch, 64 the coronary vasculature, 8,14,24 the femoral arteries, 42 and the carotid 22,44,49 and aortic 2,30,48 bifurcations. Many of these arterial characterization studies involved planar analysis of angiograms, maximum intensity projections (MIPs) from magnetic resonance angiography (MRA) or views of vascular casts for assessing 3D bifurcations and non-planar arterial curvature; methods which inevitably incur projection errors and vessel foreshortening when viewing from any direction.…”