Wargon M, Laude D, Girard A, Elghozi J L
Centre d'Investigation Clinique, Association Claude Bernard, Hôpital Necker-Enfants Malades, Paris, France.
Fundam Clin Pharmacol. 1998;12(4):451-6. doi: 10.1111/j.1472-8206.1998.tb00971.x.
Respiratory sinus arrhythmia (RSA) is often quantified by computing the spectra of heart period (HP) or of its reciprocal heart rate (HR) at the respiratory frequency. This study was undertaken to describe the effect of an acute beta-blockade achieved with bisoprolol on RSA, obtained during a calibrated breathing (breathing frequency 0.25 Hz, tidal volume VT 500 or 700 mL) in 15 normal volunteers, using a double-blind, placebo-controlled, cross-over method. The two heart signals were computed and the RSA values were compared to the individual estimates of vagal tone obtained using an additional atropine injection. The difference between the HP (or HR) value obtained after beta-blockade and the HP (or HR) value observed following the double blockade (bisoprolol plus atropine) was taken as an index of cardiac vagal tone. Bisoprolol administration resulted in a significant reduction in HR reaching 60.3 +/- 1.4 bpm at VT of 500 mL (compared to 70.5 +/- 1.8 bpm with placebo, P < 0.001). Changes in HP were also significant with an increase in HP reaching 1004.5 +/- 22.2 msec at this controlled VT (compared to 860.3 +/- 21.5 msec with placebo, P < 0.001). Similar changes were observed at a VT of 700 mL. The relationship between RSA in bpm and vagal tone was not significant for HR while a significant positive relationship was observed between RSA in msec and vagal tone for the two respiratory patterns (r = 0.65 for a tidal volume of 500 mL, P < 0.01, and r = 0.62 for 700 mL, P < 0.05). This demonstrates that the detection of the variability effect highly depends upon the unit. The parallelism between vagal tone and RSA supports the view that the HF component of HRV in msec quantifies the vagal tone. The increased RSA during beta-blockade could well reflect this vagotonic effect of this class of drugs.
呼吸性窦性心律不齐（RSA）通常通过计算呼吸频率下的心动周期（HP）或其倒数心率（HR）的频谱来量化。本研究旨在描述在15名正常志愿者进行校准呼吸（呼吸频率0.25Hz，潮气量VT为500或700mL）期间，使用双盲、安慰剂对照、交叉方法，比索洛尔实现的急性β受体阻滞剂对RSA的影响。计算两个心脏信号，并将RSA值与使用额外阿托品注射获得的迷走神经张力个体估计值进行比较。β受体阻滞剂后获得的HP（或HR）值与双重阻断（比索洛尔加阿托品）后观察到的HP（或HR）值之间的差异被用作心脏迷走神经张力的指标。给予比索洛尔导致HR显著降低，在VT为500mL时达到60.3±1.4次/分钟（与安慰剂组的70.5±1.8次/分钟相比，P<0.001）。HP的变化也很显著，在该受控VT下HP增加到1004.5±22.2毫秒（与安慰剂组的860.3±2l.5毫秒相比，P<0.001）。在VT为700mL时观察到类似变化。对于HR，以bpm为单位的RSA与迷走神经张力之间的关系不显著，而对于两种呼吸模式，以毫秒为单位的RSA与迷走神经张力之间观察到显著的正相关（潮气量为500mL时r=0.65，P<0.01；700mL时r=0.62，P<0.05）。这表明变异性效应的检测高度依赖于单位。迷走神经张力与RSA之间的平行关系支持了以毫秒为单位的HRV的高频成分量化迷走神经张力的观点。β受体阻滞剂期间RSA的增加很可能反映了这类药物的迷走神经兴奋作用。
