Assessment of cardiac autonomic modulation during graded head-up tilt by symbolic analysis of heart rate variability
Assessment of cardiac autonomic modulation during graded head-up tilt by symbolic analysis of heart rate variability
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DOI：
10.1152/ajpheart.00006.2007
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发表时间：
2007-07-01
影响因子：
4.8
通讯作者：
Gnecchi-Ruscone, Tomaso
中科院分区：
文献类型：
--
作者：
Porta, Alberto;Tobaldini, Eleonora;Gnecchi-Ruscone, Tomaso
两个符号指数，即以三个心跳周期无显着变化（0V％）和有两个显着不同变化（2UV％）为特征的序列的百分比，已被发现分别反映交感神经和迷走神经调节的变化。我们测试了这样的假设：符号索引可以在增量平视倾斜测试期间跟踪心脏自主调节的逐渐变化。对 17 名健康受试者进行分级平视倾斜测试（0、15、30、45、60、75 和 90 度）期间心电图记录得出的心率变异性系列（250 次心跳）进行符号分析。利用与倾斜角度表现出显着线性相关性（斯皮尔曼等级顺序相关性）的受试者百分比来评估符号分析的性能。进行光谱分析以对同一系列进行比较。 0V%随着倾斜角度逐渐增加，而2UV%逐渐减少。在低倾斜角度下，2UV%的下降幅度大于0V%的上升幅度。与任何光谱指数相比，0V% 和 2UV% 的受试者中表现出与倾斜角度线性相关的比例更高。我们的研究结果表明，符号分析比频谱分析表现更好，因此，它是评估分级平视倾斜测试引起的心脏自主调节细微变化的合适方法。此外，符号分析表明，在此协议期间观察到的心脏交感神经和迷走神经调节的变化是相互的，但其特征在于绝对幅度不同。
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.