甲状腺素诱发房性和室性心律失常的实验研究

目的:应用单相动作电位技术,通过比较甲亢状态下心房肌和心室的电生理特性的改变来探讨发生房性心律失常的可能机制。方法:24只日本大耳白兔随机分为对照组(12只)和甲状腺素组(12只)。甲状腺素组腹腔注射左旋甲状腺素(L-T4)1 mg/(kg.d)复制甲状腺机能亢进模型。对照组给予等体积的生理盐水腹腔注射。两组动物各自随机分为心房组和心室组进入实验(每组6只)。采用单相动作电位记录技术记录四组心房肌和心室肌电生理指标的变化,同时程序刺激诱发房性和室性心律失常。结果:心房肌和心室肌单相动作电位时程(MAP90)、有效不应期(ERP)和ERP/MAP90比值均较对照组明显缩短,具有显著性差异;但是在给予程序性电刺激时,甲状腺素组的房性心律失常的发生率明显高于对照组;而两组间室性心律失常的发生率差异无显著性。结论:甲亢状态下房性心律失常比室性心律失常易于诱发,可能与心房肌单相动作时程和有效不应期非同步性缩短的电异质性,以及和心房解剖结构存在的各向异性密切相关。

Experimental Research of Atrial Arrhythmia and Ventricular Arrhythmia Induced by Thyroxine

Objective: To investigate the electrophysiologic changes of atrium and ventricular in hyperthyroidism rabbits and the possible mechanism of atrial arrhythmia induced by thyroxine(L-T_(4))_()using monophasic action potential recording technique.Methods: Twenty-four rabbits were randomized into control and thyroxine treated group.Rabbits were injected with L-T_(4)solution(1 mg/\) for two weeks to produce hyperthyroidism intraperitoneally in thyroxine group.Control group rabbits were injected saline with the same volume as thyroxine group,and both groups were randomized into two sub-groups as atrial and ventricular group.On the fifteenth day,electrophysiologic indices such as monophasic action potential(MAP_(90)),effective refractory period(ERP) of atrial and ventricular myocardium were recorded in three groups,and then the incidence of atrial arrhythmia and ventricular arrhythmia induced by programmed stimulation was recorded.All parameters were statistically analyzed.Results:(MAP_(90),)ERP and ERP/MAP_(90) were shorter in thyroxine group than those of control group,and the incidence of atrial arrhythmia induced by electrical stimulation in thyroxine group was significantly higher than in control group,and the rates of ventricular arrhythmia between the two groups were not different.Conclusion: Atrial arrhythmia in hyperthyroidism state is facilitated to induced,which is closely correlated with electrical heterogeneity of asynchronously shortening between MAP90 and ERP,and correlated with the anisotropy in atrial anatomic structure.