早搏致基础心搏间歇性束支阻滞的机理探讨

Mechanism of intermittent bundle branch block caused by premature beats

目的 探讨早搏致基础心搏间歇性束支阻滞(IBBB)的心电图特点及产生机理。方法 以8例典型病例为资料进行分析、探讨。结果 早搏可致基础心搏IBBB,既可使左/右束支阻滞(L/RBBB)间歇性显现,亦可促使L/RBBB一过性消失。结论 早搏致基础心搏IBBB的产生机理与下列因素的一个或多个有关:(1)频率依赖性束支阻滞(3相、4相、3+4相);(2)早搏使左、右束支激动“失同步”,一侧束支激动时间被提前,另一侧束支激动时间被延迟,致跟随出现的基础心搏只能沿一侧束支下传,从而产生IBBB;(3)蝉联现象:有时束支阻滞一旦出现,就有持续存在(无休止)的趋势;该现象可被早搏终止;(4)Ashman现象。

Objective To investigate the electrocardiogram(ECG) characteristics and mechanism of basic cardiac intermittent bundle branch block(IBBB) caused by premature beats. Methods The data of 8 typical cases were analyzed and discussed. Results Premature beat could lead to basic heart beat IBBB, which could lead to the intermittent appearance of left/right bundle branch block(L/RBBB) and the transient disappearance of L/RBBB.Conclusions The pathogenesis of IBBB induced by premature beats is related to one or more of the following factors:(1)Frequency-dependent BBB(3-phase, 4-phase, 3+4-phase);(2)Premature beats lead to "dyssynchrony" of the left and right bundle branches. The time of one bundle branch is advanced, and the time of the other bundle branch is delayed, so that the following basic beats can only be transmitted down the one bundle branch, resulting in the generation of IBBB;(3) The phenomenon of repeat: sometimes BBB once appeared, there is a persistent(endless)trend;This phenomenon can be terminated by premature contractions;(4)Ashman phenomenon.