伊布利特对犬心室颤动和心外膜细胞不应期整复性的影响

Effect of ibutilide on ventricular fibrillation and refractory period restitution in canine heart

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 effect of ibutilide on ventricular refractory period and refractory period restitution,and to explore its possible anti-fibrillatory mechanism.Methods A mapping plaque containing 10×10 unipolar electrodes spacing 2 mm was sutured on the lateral epicardium of left ventricle in six dogs.Before and after administration of ibutilide [10 μg/kg intravenously as loading dose and 0.1 mg/（kg·h） intravenously as maintenance dose],ventricular fibrillation（VF） was induced by a programmed pacing protocol.Refractory period restitution was estimated from activation recovery interval（ARI） during pacing.Ventricular effective refractory period（VERP） was measured by S1S2 pacing protocol.Results The VF inducibility was significantly decreased after administrating ibutilide（83.3% vs 16.7%,P0.01）.Ibutilide prolonged ARI [（151.0±15.6）ms vs（169.0±14.4） ms,P0.01）] and VERP [（167.0±18.6） ms vs（183.0±17.5） ms,P0.01）] and markedly reduced the maximal slope of ARI restitution curve by 43%（1.34±0.08 vs 0.76±0.06,P0.01）.Conclusions Ibutilide prolonged refractory period and flattened its restitution curve,which contributed to the lowering of VF inducibility.