REGULATION OF LEFT VENTRICULAR VOLUMES AT REST AND DURING STRESS

放射性核素脑室造影术可以准确追踪左 静息和剧烈有氧运动时的左心室容量 (前)。尽管与年龄相关的左心室容量和射血分数的变化 (EF)在以前的研究中已经显示了年龄变化在EX中的作用 在心血管适合度方面这些LV参数在EX期间一直没有得到 评估过了。要确定年龄对左心室容量的影响，独立于 身体健康水平，我们获得了门控心血池扫描在 95例23~86岁健康男性的分级最大直立周期EX。在… 整体组最大努力，左室舒张末容量指数(EDVI) 收缩末期容量指数(ESVI)随年龄增长而增加(r=0.37，P<0.01 和r=0.46，p；t；.001)，而LVEF随年龄增长而下降，r=- 0.46、p&lt；.001和每搏输出量指数(SVI)与年龄无关。在一个 49名健康状况相同的男子(最大工作负荷125-150瓦)的子组， EDVI和ESVI随年龄增长而增加，LVEF随年龄增长而下降 样本，但SVI随着年龄的增长而增加(r=0.39，p&lt；0.01)，原因是口音- EDVI增加(r=0.51，P<0.01)。心脏的年龄差异 对β-肾上腺素能刺激的反应可能是衰老变化的基础 心血管不含血流动力学。检验这一假设的一种方法是 给正常人服用一种β-肾上腺素能阻断药物 较宽的年龄范围，并将其与未被屏蔽的用户进行比较 对剧烈有氧运动的反应在很大程度上是由 通过β-肾上腺素能激活，其效率依赖于 年事已高。为了确定急性β-受体阻滞剂是否会减弱 这些标准的年龄变化在心血管ex表现中，我们进行了 一组BLSA男性患者静脉注射心得安后的最大循环ex。在……里面 25名年龄在28-72岁的男性在负荷高峰时接受心得安、EDVI静脉注射 随年龄增长而下降(r=-0.20)，导致SVI随年龄增长而下降(r= 0.48，p&lt；0.05)未预先发送到未被屏蔽的人员。心随心衰 接受普萘洛尔治疗的男性年龄变钝(0.46次/分钟/年) 控制(1.09次/分钟/年)。左心室射血分数最大值随年龄增长而下降。 存在(r=-0.50，p&lt；.01)和不存在(r=-0.45，p&lt；.0001) β-肾上腺素能阻滞剂。坡度移动的主要原因是 心得安存在时的年龄回归显著增加 EDVI和SVI，以及年轻男性心率的大幅下降。因此，虽然 年龄相关性最大左心室射血分数下降未受影响，急性β-受体阻滞剂 逆转直立周期中与年龄相关的脑室扩张 并使最大心率下倾变钝。最终的效果是一种突出的 最大CI随年龄增长呈下降趋势。

Radionuclide ventriculography can accurately track changes in left ventricular (LV) volumes at rest and during vigorous aerobic exercise (EX). Although age-associated changes in LV volumes and ejection fraction (EF) have been shown during EX in prior studies, the role of age changes in cardiovascular fitness on these LV parameters during EX has not been assessed. To determine the effect of age on EX LV volumes, independent of physical fitness level, we obtained gated cardiac blood pool scans during graded maximal upright cycle EX in 95 healthy men ages 23-86 yr. At maximal effort in the overall group, LV end-diastolic volume index (EDVI) and end-systolic volume index (ESVI) increased with age (r = 0.37, p<.01 and r = 0.46, p<.001 re-spectively) while LVEF declined with age, r = - 0.46, p<.001 and stroke volume index (SVI) was unrelated to age. In a subset of 49 men of homogeneous fitness (maximal workload 125-150 watts), EDVI and ESVI increased and LVEF decreased with age as in the overall sample, but SVI increased with age (r = 0.39, p<.01) due to an accent- uated increase in EDVI (r = 0.51, p<.001). Age differences in the cardiac response to beta-adrenergic stimulation may underlie aging changes in cardiovascular EX hemodynamics. One way to test this hypothesis is to administer a beta-adrenergic blocking drug to normal individuals across a broad age range and compare the EX re-sponse to that in the unblocked condition The response to strenuous aerobic EX is mediated in large part by beta-adrenergic activation, the efficiency of which de-clines with advancing age. To ascertain whether acute beta-blockade would attenu-ate these normative age changes in cardiovascular EX performance, we performed maximal cycle EX in a group of BLSA men after intravenous propranolol. In 25 men ages 28-72 yr given intravenous propranolol, EDVI at peak workload declined with age (r= -0.20) causing an age-associated decline in SVI (r= 0.48, p<0.05) not pre-sent in the unblocked men. The decline in heart with age in propranolol-treated men was blunted (0.46 beats/min/yr) compared to controls (1.09 beats/min/yr). Max-imal LVEF declined with age similarly in the presence (r= -0.50, p<.01) and the absence (r= -0.45, p<.0001) of beta-adrenergic blockade. The primary reason for the slope shifts in the age regressions in the presence of propranolol was a large increase in EDVI and SVI and a large decrease in HR in younger men. Thus, while the age-associated decline in maximal LVEF is unaffected, acute beta-blockade reverses the age-associated ventricular dilatation during upright cycle and blunts the de-cline in maximal HR. The net effect is an accentuated decline of maximal CI with age.