Mølgaard H, Sørensen K E, Bjerregaard P
University Department of Cardiology, Skejby Sygehus, Arhus N, Denmark.
Am J Cardiol. 1991 Sep 15;68(8):777-84. doi: 10.1016/0002-9149(91)90653-3.
Quantification of variations in instantaneous heart rate (HR) can be used to evaluate cardiac autonomic function. A 24-hour standard deviation of all normal RR intervals less than 50 ms in survivors of myocardial infarction has been shown to be an independent marker of adverse prognosis. Twenty-four-hour HR variability in 140 healthy subjects aged 40 to 77 years was determined as (1) standard deviation, and (2) percentage of successive RR interval differences greater than 6%--an index of parasympathetic activity. The 24-hour standard deviation varied between 68 and 261 ms (median 139). Range for index of parasympathetic activity was 0.1 to 29.6% (median 4.4). Twenty percent of the interindividual variation in HR variability was explained by impact of risk factors. Standard deviation was uninfluenced by age, whereas parasympathetic activity decreased by increasing age. High physical training level was independently associated with significantly higher standard deviation (and parasympathetic activity) values during both day and night. Hourly figures of standard deviation decreased during the night, whereas parasympathetic activity increased and peaked early morning. Standard deviation values as low as those reported in high-risk patients were not observed, but comparable low values for, and lack of diurnal variation in, parasympathetic activity were seen in healthy subjects also. In conclusion, risk factors and, in particular, the physical training level have impact on 24-hour HR variability in healthy subjects. This may prove valuable for modification of cardiac autonomic activity in patients.
瞬时心率（HR）变化的量化可用于评估心脏自主神经功能。心肌梗死幸存者中所有正常RR间期小于50毫秒的24小时标准差已被证明是不良预后的独立标志物。对140名年龄在40至77岁的健康受试者的24小时心率变异性进行了测定，测定指标为：（1）标准差，以及（2）连续RR间期差异大于6%的百分比——这是副交感神经活动的一个指标。24小时标准差在68至261毫秒之间（中位数为139）。副交感神经活动指标范围为0.1%至29.6%（中位数为4.4%）。心率变异性个体间差异的20%可由危险因素的影响来解释。标准差不受年龄影响，而副交感神经活动随年龄增长而降低。高体育锻炼水平与白天和夜间显著更高的标准差（和副交感神经活动）值独立相关。标准差的每小时数值在夜间降低，而副交感神经活动增加并在清晨达到峰值。未观察到与高危患者报告的标准差一样低的值，但在健康受试者中也观察到了副交感神经活动的可比低数值以及缺乏昼夜变化。总之，危险因素，尤其是体育锻炼水平，对健康受试者的24小时心率变异性有影响。这可能对改变患者的心脏自主神经活动具有重要价值。
