Goldberger J J, Kim Y H, Ahmed M W, Kadish A H
Department of Medicine, Northwestern University, Chicago, Illinois, USA.
J Cardiovasc Electrophysiol. 1996 Jul;7(7):594-602. doi: 10.1111/j.1540-8167.1996.tb00567.x.
Time-and frequency-domain measurements of heart rate variability have been used as indices of parasympathetic tone. However, studies of the effect of parasympathetic stimulation on these indices in humans have yielded conflicting results.
This study evaluated the effects of parasympathetic stimulation on heart rate variability. Twelve normal subjects (7 males, 5 females; age 24.8 +/- 3.4 years) were evaluated in the Clinical Research Center. Five-minute ECG recordings were obtained at baseline and during graded phenylephrine infusions (0.3 and 0.6 micrograms/kg per min). Recordings were made during spontaneous respiration and when breathing was timed with a metronome at 15 cycles/min. Heart rate variability analysis was performed using standard time- and frequency-domain parameters. Graded phenylephrine infusion resulted in a progressive increase in blood pressure and RR interval but no consistent changes in heart rate variability for the group. The results during normal versus metronome breathing were similar. Stepwise linear regression analysis revealed that the phenylephrine-induced changes in heart rate variability were inversely correlated with the baseline heart rate variability and not related to the baseline RR interval or the phenylephrine-induced change in RR interval.
These findings suggest that the respiratory variation in "parasympathetic effect" typically observed at the sinus node can be either increased or decreased by parasympathetic stimulation, depending on the initial level of parasympathetic tone and the intensity of stimulation. This resolves the previously conflicting data. Thus, evaluation of parasympathetic tone using heart rate variability techniques should be cautiously undertaken.
心率变异性的时域和频域测量已被用作副交感神经张力的指标。然而，关于副交感神经刺激对人类这些指标影响的研究结果相互矛盾。
本研究评估了副交感神经刺激对心率变异性的影响。在临床研究中心对12名正常受试者（7名男性，5名女性；年龄24.8±3.4岁）进行了评估。在基线时以及在分级输注去氧肾上腺素（0.3和0.6微克/千克每分钟）期间获取5分钟的心电图记录。记录在自主呼吸期间以及当呼吸由节拍器以15次/分钟定时时进行。使用标准的时域和频域参数进行心率变异性分析。分级输注去氧肾上腺素导致血压和RR间期逐渐增加，但该组心率变异性没有一致的变化。正常呼吸与节拍器呼吸时的结果相似。逐步线性回归分析显示，去氧肾上腺素引起的心率变异性变化与基线心率变异性呈负相关，与基线RR间期或去氧肾上腺素引起的RR间期变化无关。
这些发现表明，通常在窦房结观察到的“副交感神经效应”的呼吸变化可通过副交感神经刺激而增加或减少，这取决于副交感神经张力的初始水平和刺激强度。这解决了先前相互矛盾的数据。因此，使用心率变异性技术评估副交感神经张力时应谨慎进行。
