Nixon J V, Hallmark H, Page K, Raven P R, Mitchell J H
Am J Cardiol. 1985 Dec 1;56(15):932-7. doi: 10.1016/0002-9149(85)90407-2.
The effects of increasing and decreasing cardiac preload by 15% on the left ventricular (LV) performance of 11 carefully screened normal subjects aged 61 to 73 years were examined. Comparisons were made with 11 subjects aged 21 to 28 years. Two-dimensional echocardiograms were obtained before and at the termination of 5 degrees of head-down tilt for 90 minutes and at the termination of graded lower body negative pressure to -40 mm Hg. Heart rates and blood pressures were unchanged after physiologic interventions. Changes in LV end-diastolic and stroke volumes were similar but of a smaller magnitude in the older subjects compared with changes in younger subjects. When LV end-diastolic volumes obtained at each extreme of preload variation were compared, the range of mean change was less in the older (23 ml, 26%) than in the younger subjects (31 ml, 41%). Control LV end-diastolic and end-systolic volumes were greater in the older subjects. This study shows that despite larger control LV volumes, alterations in preload produce changes in the LV end-diastolic and stroke volumes of these older subjects that conform to the normal LV function curve, but that these responses are diminished compared with changes in younger subjects, suggesting an age-related change in diastolic stiffness.
研究了在11名经过精心筛选的61至73岁正常受试者中，将心脏前负荷增加和减少15%对左心室（LV）功能的影响，并与11名21至28岁的受试者进行了比较。在90分钟的5度头低位倾斜结束时以及分级下肢负压至-40 mmHg结束时，获取二维超声心动图。生理干预后心率和血压未发生变化。与年轻受试者相比，老年受试者左心室舒张末期容积和每搏量的变化相似，但幅度较小。当比较在预负荷变化的每个极端情况下获得的左心室舒张末期容积时，老年受试者的平均变化范围（23 ml，26%）小于年轻受试者（31 ml，41%）。老年受试者的对照左心室舒张末期和收缩末期容积更大。这项研究表明，尽管老年受试者的对照左心室容积较大，但预负荷的改变会使这些老年受试者的左心室舒张末期容积和每搏量发生变化，这些变化符合正常左心室功能曲线，但与年轻受试者的变化相比有所减弱，提示存在与年龄相关的舒张期僵硬度变化。
