Cunningham D A, Petrella R J, Paterson D H, Nichol P M
Department of Physiology, Faculty of Physical Education, University of Western Ontario, London, Canada.
Can J Physiol Pharmacol. 1988 Nov;66(11):1425-32. doi: 10.1139/y88-232.
To test the hypothesis that altered hemodynamic responses to postural changes are associated with aging, cardiovascular responses to head-up tilt (HUT) and head-down tilt (HDT) were examined in 12 healthy young (average age, 24.6 +/- 1.7 years) and 12 healthy elderly (average age, 68.6 +/- 2.2 years) men. Subjects were passively tilted from supine to 30 degrees, 60 degrees, and 90 degrees HUT and HDT. Responses to these perturbations were determined 5 min after tilting with measures of heart rate (HR), blood pressure (SBP, DBP), and echocardiographically determined left ventricular diameter in systole and diastole (LVIDs, LVIDd). In HUT there were no significant age effects. In both young and elderly, SBP decreased significantly (p less than 0.05), and DBP and HR increased significantly. Ejection fraction (EF), mean arterial blood pressure (MABP), and rate-pressure product (RPP) were unchanged in both groups. In HDT, the hemodynamic responses of the young and elderly were in opposite directions and significant age effects were found for SBP, DBP, HR, LVIDs, EF, MABP, and RPP. In HDT, the young appear to increase cardiac output primarily due to an increase in EF and end-diastolic volume (LVIDd), while HR is unchanged and SBP is decreased. MABP is unchanged, suggesting a small decrease in total peripheral resistance. The elderly may increase cardiac output slightly, owing to an increase in LVIDd with no change in EF, and a large increase in HR. Afterload increased markedly, therefore attenuating any increase in cardiac output.(ABSTRACT TRUNCATED AT 250 WORDS)
为了验证血流动力学对姿势变化的反应改变与衰老相关这一假设，我们对12名健康年轻男性（平均年龄24.6±1.7岁）和12名健康老年男性（平均年龄68.6±2.2岁）进行了研究，检测他们对抬头倾斜（HUT）和低头倾斜（HDT）的心血管反应。受试者从仰卧位被动倾斜至HUT和HDT的30度、60度和90度。倾斜5分钟后，通过测量心率（HR）、血压（收缩压、舒张压）以及超声心动图测定的收缩期和舒张期左心室直径（LVIDs、LVIDd）来确定对这些扰动的反应。在HUT试验中，未发现显著的年龄效应。无论年轻组还是老年组，收缩压均显著下降（p<0.05），舒张压和心率显著升高。两组的射血分数（EF）、平均动脉压（MABP）和速率压力乘积（RPP）均无变化。在HDT试验中，年轻人和老年人的血流动力学反应方向相反，并且在收缩压、舒张压、心率、LVIDs、EF、MABP和RPP方面发现了显著的年龄效应。在HDT试验中，年轻人似乎主要通过增加EF和舒张末期容积（LVIDd）来增加心输出量，而心率不变，收缩压下降。MABP不变，表明总外周阻力略有下降。老年人可能由于LVIDd增加而EF不变，以及心率大幅增加而使心输出量略有增加。后负荷显著增加，因此削弱了心输出量的任何增加。（摘要截选至250字）
