心房肌复极的电生理特性的实验研究

The Experimental Study for the Electrophysiological Characteristic of Atrial Repolarization

目的:本研究使用单相动作电位技术(MAP)对在体犬左、右心房肌的复极电生理特性进行研究,以探讨心房肌在房颤(AF)发生中的基质作用。方法:应用单相动作电位技术记录14只犬左、右心房肌的动作电位时程(APD),通过程序刺激记录心房有效不应期(ERP)及相对不应期(RRP),观察左、右心房肌反复心房激动(RAF),在S_1S_2的早搏刺激后,发生2个以上的连续心房活动)、电交替(S_1S_2起搏间期缩短的程度达到了某一值可以产生在连续的心房间APD形态和间期的交替变化)及AF的诱发。结累:14只犬左心房APD_(90)小于右心房[(157.4±43.5),(170.9±37.9),P<0.05]。S_1S_2间期递减至(130±32)ms时,可出现RAF,共诱发出15阵RAF,左房11阵,右房4阵,左房RAF的发生率明显多于右房(P<0.05);心房S_1S_1超速起搏刺激在(162±25)ms产生APD时限和幅度的交替,14只犬共记录13阵电交替(左房8阵,右房5阵)。研究中左房刺激发作38阵房颤,明显多于右房23阵(P<0.05)。结论:左、右心房肌复极间具有不同的电生理特性,左房较右房更易诱发电交替和RAF,预示心房肌复极的不稳定性,是AF发生和维持的基质。

Objective：This study investigated the eleetrophysiological properties of atrial repolarization by monophasic action potential（MAP） in order to explore the mechanism of paroxysmal atrial fibrillation（AF） initiation and maintenanee.Methods：Monophasie action potential（MAP） were recorded from left and right atrium in 14 canine,effective refractory period （ERP）,action potential duration（APD） at 90% repolarization （APD90）, Repetitive atrial firing（RAF,the occurrence of 2 or more successive premature atrial activations with return cycle of 250 msec or less following atrial stimulation） and APD alternans（the difference in APD between 2 consecutive beats, were induced by overdrive pacing at LA and RA） were induced by use of programmed stimulation at LA and RA. In the study, episodes of PAF were recorded and analyzed.Results：APD90 were significantly shorter in the left atrium compared to the right atrium[（157.4±43.5） vs（170.9±37.9）,P〈0.05].Tbe mean S1S2 interval induced RAF was（130±32）ms. In all.15 RAF were induced in 14 dogs.RAF induced in LA were more than in RA（11 vs 4,P〈0.05）.In all, alternans of APD were induced at CL of （162±25）ms.13 APD alternans were induced at LA（8） and RA（5） of 14 dogs.in total,61 episodes of PAF were induced in 14 canines.38 episodes of PAF were induced in the left atrium and more than in the right atrium（23,P〈0.05）.Conclusions：The incidence of repetitive atrial firing and altemans was significantly higher in LA than in RA.Heterogeneity between LA and RA repolarization creates subatrate for re-entrant arrhythmias and vulnerability to fibrillation.The atrium plays a central role in the initiation olAF by serving as a substrate for generators of fibrillatory activity.