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目的:通过观察伊布利特对心室不应期及不应期整复性的影响,探讨其发挥抗心室颤动(VF)可能的作用机制。方法:选取6只健康成年比格犬,开胸暴露心脏,在每只犬的左心室左侧后壁心外膜上缝上电极板(共10×10个单极电极),每个电极间的距离为2 mm。通过S1S2测定心室有效不应期(VERP),利用连续刺激法诱发VF,同时记录每个电极的激动恢复间期(ARI)。通过记录到的ARI来评估心室不应期整复性曲线的最大斜率,完成基础值(基础对照)测定后,给予伊布利特[静脉推注10μg/kg,随后0.1 mg/(kg.h)静脉滴注维持],并重复测定用药前的参数。结果:与基础对照相比,伊布利特可显著降低VF诱发率(83.3%比16.7%,P<0.01),同时可明显延长犬的ARI[(151.0±15.6)ms比(169.0±14.4)ms,P<0.01]及VERP[(167.0±18.6)ms比(183.0±17.5)ms,P<0.01]。与基础对照相比,伊布利特可显著降低不应期整复性曲线的最大斜率(1.34±0.08比0.76±0.06,P<0.01)。结论:伊布利特可通过延长心室不应期及降低不应期整复性曲线的最大斜率发挥预防VF的作用。
OBJECTIVE: To investigate the possible mechanism of anti-ventricular fibrillation (VF) by observing the effects of ibutilide on ventricular refractory period and refractory period. Methods: Six healthy adult Beagle dogs were selected and their hearts exposed by thoracotomy. Electrode plates (10 × 10 monopolar electrodes) were placed on the epicardium of the left posterior wall of left ventricle in each dog. Each electrode The distance is 2 mm. Ventricular effective refractory period (VERP) was determined by S1S2, VF was induced by continuous stimulation, and the recovery period (ARI) of each electrode was recorded. The maximum slope of the ventricular refractory period integrality curve was assessed by the documented ARI, and after the baseline (basal control) determination was completed, ibutilide [iv bolus 10 μg / kg followed by 0.1 mg / (kg.h ) Intravenous infusion maintenance], and repeated determination of parameters before treatment. Results: Compared with the control group, ibutilide significantly reduced the rate of VF induction (83.3% vs. 16.7%, P <0.01) and significantly prolonged ARI (151.0 ± 15.6 ms vs 169.0 ± 14.4) ms, P <0.01] and VERP [(167.0 ± 18.6) ms vs (183.0 ± 17.5) ms, P <0.01]. Ibutilide significantly reduced the maximum slope of the refractory period (1.34 ± 0.08 vs. 0.76 ± 0.06, P <0.01) compared with the baseline control. Conclusion: Ibutilide can prevent VF by prolonging the ventricular refractory period and decreasing the maximum slope of the refractory period integral curve.