RACE & GENDER DIFFERENCES IN INTRACEREBRAL & CAROTID ARTERIAL VELOCITY--AGING

Yogi Nagai博士于1996年3月加入LSB，与我们一起从事该项目，并于1998年3月完成了他的奖学金。本项目利用多普勒超声对BLSA参与者的脑内血流速度和阻力、颈动脉血流速度进行研究。目的是确定这些与脑血管疾病相关的因素如何随年龄变化。它补充了博士的研究。Lakatta和Fleg在LCS中对动脉硬度的影响，通过探索硬度对最终器官（大脑）的影响。在过去的一年里，我们完成并发表了Nagais博士在NIA任职期间开始的几篇手稿。(1)我们证明了颈总动脉内膜-内侧厚度（CCA IMT），一个建议的动脉粥样硬化指标，在无症状的老年受试者中，在跑步机运动中缺血性st段反应增加。颈总动脉（CCA）的内膜内侧厚度（IMT）随着年龄的增长而增加，同时伴有CCA扩张和收缩压的升高，且性别不同。冠状动脉心脏疾病（CHD）的存在加重了IMT的改变。事实上，无症状的冠心病患者的血管壁增厚比有症状的冠心病患者少，但比健康对照者多。IMT每增加0.1 mm与1.78倍（95% CI 1.34-2.36, p<0.0001）的运动试验阳性或明显CAD风险增加独立相关。(2)建立了一种新的指标，即衰减指数（DI），用于检测收缩期后期血流速度的变化。它是用新开发的计算机程序从录像带上记录的多普勒波中获得的。DI与主动脉僵硬直接相关，在较小程度上与动脉外周阻力相关。与其他测量颈动脉硬度的方法相比，它被发现与年龄和冠心病独立相关。我们认为DI代表了Windkessel效应的临床测量。(3) AGI和弹性超声指标表现出血管刚度的不同特征。增强指数（AGI）（r= 0.38, p= 0.000）和Ep随年龄的增长而增加，DC（r=- 0.43, p= 0.000）和CC（r=- 0.25, p= 0.021）随年龄的增长而降低，而YM不随年龄的增长而变化。在控制年龄后，Ep和YM与AGI有显著相关性（r2= 0.23, r2= 0.18），但AGI与超声指标无显著相关性。研究结果表明，AGI和超声测量应该比单独测量更好地了解动脉随年龄的变化。(4)我们研究了雌激素对绝经后妇女动脉硬化的影响。绝经后服用雌激素的妇女动脉硬化比不服用激素替代的妇女少。(5)我们比较了成年期间健康女性和男性的CCA、颈内动脉和大脑中动脉的血流速度。-多普勒超声脑血流速度动脉硬度颈动脉-人类受试者

Dr. Yogi Nagai joined LSB in March 1996 to work on the project with us and completed his fellowship in March 1998. The project studies intracerebral blood flow velocity and resistance, and carotid blood flow velocity using doppler ultrasonography in BLSA participants. The goal is to determine how these factors, which are associated with cerebrovascular diseases, change with age. It complements the studies of Drs. Lakatta and Fleg in the LCS on arterial stiffness, by exploring the effects of stiffness on an end organ (the brain). Over the past year, we have completed and published several manuscripts started during Dr. Nagais tenure at NIA. (1)We demonstrated that intimal-medial thickness of the common carotid artery (CCA IMT), a proposed index of atherosclerosis, is increased in asymptomatic older subjects with an ischemic ST-segment response to treadmill exercise. Intimal medial thickness (IMT) of the common carotid artery (CCA) increases with age concomitant with CCA dilatation, elevation of systolic blood pressure and differently by gender. The change in IMT is exacerbated by the presence of coronary heart disease (CHD). In fact, individuals with asymptomatic CHD show wall thickening that is less than observed in symptomatic CHD and greater than healthy controls. Each 0.1 mm increase in IMT was independently associated with a 1.78 fold (95% CI 1.34-2.36, p<0.0001) increased risk for concordant positive exercise tests or manifest CAD. (2) A new index, the decay index (DI), was developed to examine changes in flow velocity during late systole. It is obtained from the Doppler waves recorded on videotapes using a newly developed computer program. DI is directly associated with aortic stiffness and to a lesser extent with arterial peripheral resistance. It was found to be independently related to age and CHD, as compared to other measures of carotid stiffness. We have argued that DI represents a clinical measure of the Windkessel effect. (3) AGI and ultrasonographical indices of elasticity express different characteristic of vascular stiffness. Augmentation index (AGI)(r=.38, p=.000) and Ep increased with age, DC(r=-.43, p=.000) and CC(r=-.25, p=.021) decreased with age, while YM did not change with age. AGI did not significantly correlate with the ultrasonographical indices, though Ep and YM had significant correlations with AGI after controlling for age (r2=.23, r2=.18, respectively). The findings suggest that both the AGI and ultrasonographic measurements should give a better understanding of arterial changes with age, than either measurement alone. (4) We examined the effect of estrogen on arterial stiffness in postmenopausal women. Postmenopausal women who have taken estrogen show less stiff arteries than women who do not take hormone replacement. (5) We have compared the flow velocities in CCA, internal carotid and middle cerebral arteries in healthy women and men across the adult life span. - doppler ultrasonography cerebral blood flow velocity arterial stiffness carotid artery - Human Subjects