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

该项目在巴尔的摩老年参与者纵向研究中使用多普勒超声研究脑内血流速度和阻力，以及颈动脉血流速度。目标是确定这些与脑血管疾病相关的因素如何随着年龄的增长而变化，并与心血管疾病有关。动脉弹性可以通过颈动脉超声进行评估，但其与主动脉僵硬的关系尚未完全阐明。我们用脉搏波速度(APWV)和颈总动脉(CCA)的压力-应变弹性模数(EP)对BLSA中的主动脉硬度进行LCS测量，以检验两者之间的关系。CCA、EP和APWV均随年龄增长而增加，男女差异无统计学意义。解释APWV最简约的模型包括CCA、EP和年龄(R2=.59，p&lt；.001)，但不包括BP。颈动脉僵硬与APWV之间的相关性提示颈动脉多普勒超声可能有助于评估动脉僵硬。我们研究了172名女性患者的年龄和当前雌激素替代治疗(ERT)对颈总动脉(CCA)僵硬的影响，其中包括37名目前正在接受ERT治疗的女性。僵硬指数被定义为收缩压和舒张压(BP)的比值除以心动周期内直径增加的分数的对数。刚性指数随年龄增长呈线性增加(r=0.001.6 9，p&lt；0.0 1)，且绝经后不使用者的僵硬指数低于绝经后未使用者(8.0？2.0 vs 9.7？3.1，p&lt；0.0 1)。在调整了血压和其他心血管危险因素后，年龄和ERT对僵硬指数的影响仍然存在。考虑到年龄的影响，使用ERT的患者的僵硬指数低于绝经后不使用ERT的患者。与年龄相关的颈总动脉僵硬增加可通过绝经后ERT减少。从颈动脉多普勒测定动脉硬度需要超声诊断师的交互式测量，这增加了临床检查的几分钟时间。为了简化这一过程，我们通过一个自动识别曲线形状的程序，探索了将多普勒波形的形状作为动脉僵硬的衡量标准。将指数函数应用于峰后ICA多普勒波形图。108个无狭窄ICA的指数系数(DI)与APWV(r=0.57)、SBP(r=0.45)呈中度相关，与RI(r=0.54)、PI(r=0.44)、SDR(r=0.54)呈中度相关，APWV和SBP也与阻力指标呈正相关。无狭窄颈内动脉的DI与中央动脉僵硬有关，与外周阻力适度相关。我们目前正在研究BLSA中几项颈动脉测量与酒精使用之间的关系。我们发现，轻度到中度饮酒与动脉弹性增强和颈总动脉僵硬程度降低有关。观察到动脉壁厚度和直径之间的相关性不那么显著。这些变化与血压和年龄无关。动脉对酒精使用的反应可能是其对心血管疾病保护作用的一种机制。

The project studies intracerebral blood flow velocity and resistance, and carotid blood flow velocity using doppler ultrasonography in Baltimore Longitudinal Study of Aging participants. The goal is to determine how these factors, which are associated with cerebrovascular diseases, change with aging and are related to cardiovascular disease. Arterial elasticity can be assessed using carotid ultrasonography, but its association with aortic stiffness has not been completely clarified. We examined the relationship by comparing LCS measurements of aortic stiffness in the BLSA using aortic pulse wave velocity (APWV) and the common carotid artery (CCA) pressure-strain elastic modulus (Ep). Both CCA Ep and APWV increased with age and similarly for women and men. The most parsimonious model to explain APWV included CCA Ep and age (r2=.59, p<.001), but not BP. The association between CCA stiffness and APWV suggest that carotid doppler ultrasonography may be useful in assessing arterial stiffness. We have examined the influence of age and current estrogen replacement therapy (ERT) on common carotid arterial (CCA) stiffness in 172 women, including 37 current postmenopausal ERT users. A stiffness index was defined as the logarithm of the ratio of systolic to diastolic blood pressure (BP) divided by the fractional diameter increase during the cardiac cycle. The stiffness index increased linearly with age (r=0.69, p<0.001), and was lower in ERT users than in postmenopausal nonusers (8.0?2.0 vs 9.7?3.1, p<0.01). The effects of age and ERT on the stiffness index persisted after adjustments for BP and other cardiovascular risk factors. The stiffness index was lower in ERT users than in postmenopausal nonusers after considering the effects of age. Age-associated increases in CCA stiffness are reduced by postmenopausal ERT. The determination of arterial stiffness from carotid doppler requires interactive measurements by the sonographer that adds several minutes to the clinical examination. To simplify the process, we have explored using the shape of the doppler waveform as a measure of arterial stiffness with a program that automatically identifies the shape of the curve. An exponential function was applied to the post-peak ICA Doppler waveform contour. The exponential coefficient, termed 'Decay Index' (DI), was calculated for 108 stenosis-free ICAs and was moderately correlated with APWV (r=0.57) and SBP (r=0.45), and with RI (r=0.54), PI (r=0.44) and SDR (r=0.54), whereas APWV and SBP were also correlated with the resistance measures. DI from stenosis-free ICA is associated with central arterial stiffness and modestly with peripheral resistance. We are currently examining the relationship between several carotid arterial measurements and alcohol usage in the BLSA. We find that mild to moderate alcohol usage is associated with greater arterial elasticity and decreased stiffness in the common carotid artery. A less impressive association was observed with arterial wall thickness and diameter. The changes were independent of blood pressure and age. The response of the artery to alcohol usage may represent one mechanism for its protective effect against cardiovascular disease.