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首页> 外文期刊>American Journal of Physiology >Assessment of cardiac autonomic modulation during graded head-up tilt by symbolic analysis of heart rate variability.
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Assessment of cardiac autonomic modulation during graded head-up tilt by symbolic analysis of heart rate variability.

机译：通过对心率变异性的符号分析，评估平缓向上倾斜时的心脏自主神经调制。

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Two symbolic indexes, the percentage of sequences characterized by three heart periods with no significant variations (0V%) and that with two significant unlike variations (2UV%), have been found to reflect changes in sympathetic and vagal modulations, respectively. We tested the hypothesis that symbolic indexes may track the gradual shift of the cardiac autonomic modulation during an incremental head-up tilt test. Symbolic analysis was carried out over heart period variability series (250 cardiac beats) derived from ECG recordings during a graded head-up tilt test (0, 15, 30, 45, 60, 75, and 90 degrees ) in 17 healthy subjects. The percentage of subjects showing a significant linear correlation (Spearman rank-order correlation) with tilt angles was utilized to evaluate the performance of symbolic analysis. Spectral analysis was carried out for comparison over the same series. 0V% progressively increased with tilt angles, whereas 2UV% gradually decreased. The decline of 2UV% was greater than the increase of 0V% at low tilt angles. Linear correlation with tilt angles was exhibited in a greater percentage of subjects for 0V% and 2UV% than for any spectral index. Our findings suggest that symbolic analysis performed better than spectral analysis and, thus, is a suitable methodology for assessment of the subtle changes of cardiac autonomic modulation induced by a graded head-up tilt test. Moreover, symbolic analysis indicates that the changes of cardiac sympathetic and vagal modulations observed during this protocol were reciprocal but characterized by different absolute magnitudes.
机译：已经发现两个符号索引，分别以三个心动周期为特征的序列百分比无明显变化（0V％）和具有两个显着不同的变化（2UV％），分别反映了交感和迷走神经调制的变化。我们测试了这样的假设，即在递增的抬头向上倾斜测试期间，符号索引可能会跟踪心脏自主神经调制的逐渐变化。在17位健康受试者的分级抬头倾斜测试（0、15、30、45、60、75和90度）中，对源自心电图记录的心电周期变异性系列（250次心跳）进行了符号分析。显示与倾斜角度具有显着线性相关性（Spearman秩相关性）的对象百分比用于评估符号分析的性能。进行光谱分析以比较同一系列。 0V％随倾斜角度逐渐增加，而2UV％逐渐降低。在低倾斜角度下，2UV％的下降大于0V％的上升。在0V％和2UV％的受试者中，与任何光谱指数相比，与倾斜角的线性相关性更大。我们的发现表明，符号分析的效果优于频谱分析，因此，它是一种适合的方法，用于评估由分级抬头倾斜测试引起的心脏自主神经调节的细微变化。此外，符号分析表明，在该方案中观察到的心脏交感和迷走神经调制的变化是相互的，但具有不同的绝对幅度。

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