Three-dimensional blood flow in bifurcations : computational and experimental analyses and clinical applications

In this report, the issues discussed at a multidisciplinary symposium on blood flow in bifurcations are summarized. Topics adressed are (1) flow analysis in vitro models, using visualization and laser Doppler anemometer techniques, and numerical models; (2) the influence of (physiological) factors, such as vessel wall distensibility and vessel geometry, on the flow field; (3) the noninvasive assessment of arterial wall properties in humans, and (4) the noninvasive determination of flow patterns in humans, paying special attention to ultrasound techniques and magnetic resonance imaging. It was empasized that it is of utmost importance to obtain more detailed information, preferably three-dimensional, about flow field in bifurcations, not only from a diagnostic point of view but also to get more insight into the relation, if any, in between flow patterns and atheregenesis. It was agreed that plaque geometry and dynamics should be studied in more detail, especially in relation to plaque fissuring and rupturing. There is a need for the noninvasive assessment of wall shear rate and, hence, to be able to calculate wall shear stress, because these parameters have been shown to be important determinants of endothelial cell function

Menopausal status and distensibility of the common carotid artery

Although several studies have shown that exogenous estrogens have beneficial effects on arterial characteristics, the effect of endogenous estrogen on the vascular system is still unknown. In this study, distensibility, an indicator of arterial elasticity, of the common carotid artery was compared in pre- and postmenopausal women. The study comprised 93 premenopausal and 93 postmenopausal women of similar age (range, 43 to 55 years). Women were selected from respondents to a mailed questionnaire about the menopause, which was sent to all women aged 40 to 60 years in the Dutch town of Zoetermeer (n=12 675). Postmenopausal women who were at least 3 years past natural menopause or whose menses had stopped naturally before age 48, were age-matched with premenopausal women with regular menses and without menopausal complaints. The selection aimed at maximizing the contrast in estrogen status between pre- and postmenopausal women of the same age. Distensibility of the carotid artery was measured noninvasively with B-mode ultrasound and a vessel wall movement detector system. Arterial distensibility is expressed as the change in arterial diameter (distension, DeltaD) with the cardiac cycle, adjusted for lumen diameter, pulse pressure, and mean arterial blood pressure. Compared with premenopausal women, postmenopausal women had significantly lower arterial distension (DeltaD 370.5 microm [SE 9.5] versus 397.3 microm [SE 9.6]). These results suggest that the distensibility of the common carotid artery is negatively affected by natural menopause in presumed healthy women

Association between arterial stiffness and atherosclerosis: the Rotterdam Study

BACKGROUND AND PURPOSE: Studies of the association between arterial stiffness and atherosclerosis are contradictory. We studied stiffness of the aorta and the common carotid artery in relation to several indicators of atherosclerosis. METHODS: This study was conducted within the Rotterdam Study in >3000 elderly subjects aged 60 to 101 years. Aortic stiffness was assessed by measuring carotid-femoral pulse wave velocity, and common carotid artery stiffness was assessed by measuring common carotid distensibility. Atherosclerosis was assessed by common carotid intima-media thickness, plaques in the carotid artery and in the aorta, and the presence of peripheral arterial disease. Data were analyzed by ANCOVA with adjustment for age, sex, mean arterial pressure, and heart rate. RESULTS: Both aortic and common carotid artery stiffness were found to have a strong positive association with common carotid intima-media thickness, severity of plaques in the carotid artery, and severity of plaques in the aorta (P: for trend <0.01 for all associations). Subjects with peripheral arterial disease had significantly increased aortic stiffness (P:=0.001) and borderline significantly increased common carotid artery stiffness (P:=0.08) compared with subjects without peripheral arterial disease. Results were similar after additional adjustment for cardiovascular risk factors and after exclusion of subjects with prevalent cardiovascular disease. CONCLUSIONS: This population-based study shows that arterial stiffness is strongly associated with atherosclerosis at various sites in the vascular tree