右美托咪定对健康自愿者窦房结功能的影响

Effects of dexmedetomidineon sinoatrial node function of healthy volunteers

目的：观察右美托咪定（Dex）对男性健康自愿者窦房结功能的影响，监测给药过程中心率变异性的变化．探讨自主神经均衡性改变在右美托咪定致心动过缓中的作用。方法：本研究采用交叉对照设计。健康男性志愿者11例，受试者先进入右美托咪定1．0μg／kg负荷量，持续泵注量0．5μg／（kg·h）（Ⅰ组）进行试验观察．在Ⅰ组发生最低心率〈40次／min不进入下一剂量组的试验观察，8例受试者进入1．5μg／kg负荷量，持续泵注量0．75μg／（kg·h）（Ⅱ组）进行试验观察。于Dex静脉泵注前、Dex静脉泵注后（30±5）min经食管左心房调搏测定窦房结恢复时间（SNRT）、校正窦房结恢复时间（CSNRT）、窦房结总恢复时间（TRT）；于Dex静脉泵注前（T0）、Dex静脉泵注后15—20min（T1）、Dex静脉泵注后45—50min（T2）通过数字化心电工作站监测给药过程中心率变异性时域指标（SDNN、RMSSD、PNN50）及频域指标（LFnorm、HFnorm、LF／HF）变化。结果：（1）窦房结功能指标：泵注Dex前后比较两组R-R间期、SNRT、TRT均显著延长（P〈0．01），Ⅱ组CSNRT也显著延长（P〈0．01）；Ⅱ组泵药后（30±5）min SNRT、CSNRT、TRT较I组显著延长（P〈0．01）；（2）心率变异性指标：与T0比较，两组T1时点SDNN增加（P〈0．05）；两组T1、T2时点RMSSD、PNN50均显著增加（P〈0．01）；Ⅰ组T1、T2时点和Ⅱ组T1时点LFnorm降低，HFnorm升高，LF／HF均降低（P〈0．05）。结论：临床推荐剂量的右美托咪定抑制窦房结的功能，随着药物浓度的增加对窦房结抑制作用更显著。自主神经失衡在右关托咪定致心动过缓中具有重要作用。

Objective To investigate the effect of dexmedetomidine （Dex） on the sinoatrial node function of healthy volunteers, and to explore the time of the balance of autonomic nervous system is broken, and to study the mechanism of Dex-induced bradyarrhythmias. Methods This is a cross-over trial, 11 healthy male volunteers received two different doses of Dex. Parameters of SNRT, CSNRTand TRT were measured by transesophageal cardiac electrophysiology before and after the pump injection of Dex. The change of HRV time-domain index （SDNN, RMSSM, PNNS0） and frequency-domain index （LFnorm, HFnorm, LF/HF） were monitored by the workstation of digital ECG. Results The indicators date of sinoatrial node function were prolonged at （30±5）min after pump injection of Dex than the baseline in these two groups（P 〈 0.01 ）. The parameter of HRV showed the increase of vagus nerve activity in the process of administration. Conclusion The clinical doses of Dex could inhibit the function of sinoatrial node in a dose-dependent manner, and the imbalance of the autonomic nerve played an important role in Dex-induced bradyarrhythmias.