心房肌易损性与阵发性心房颤动的发生机制

目的探讨左、右心房肌复极,及其易损性与阵发性心房颤动(AF)的发生与维持机制。方法应用单相动作电位(MAP)技术记录14只犬左、右心房肌的复极达90%动作电位时程(APD90),通过S1S2程序刺激,同时记录心房有效不应期(ERP)及相对不应期(RRP),观察反复心房激动(RAF,在S1S2的早搏刺激后,发生2个以上的连续心房活动,从心房刺激到RAF第一个激动的间期必须小于250 ms)及AF的诱发。结果14只犬S1S2间期递减至130±32 ms时,可出现RAF,随后当S1S2间期缩短为110±28 ms时AF发作。AF发作前大多数可记录到RAF(66.7%);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);共诱发出18阵AF,左房诱发出12阵,右房诱发出6阵。左房的AF诱发率明显多于右房(P<0.05)。结论AF发作前多伴有RAF发作;RAF是易发生阵发性AF的特征性表现,代表心房的易损性;左右心房易损性不同。

Atrial vulnerability and paroxysmal atrial fibrillation in canine atrium

Objective To study the electrophysiological properties of left and right atrial vulnerability and its effect on the mechanism of paroxysmal atrial fibrillation （AF） initiation and maintenance. Methods Monophasic action potential （MAP） were recorded from left atrium （LA） and right atrium（RA） in 14 canine using the MAP recording-pacing combination catheter. Repetitive atrial firing （ RAF, the occurrence of 2 or more successive premature atrial activations with return cycle of 250 ms or less following atrial stimulation ） were induced by use of programmed stimulation with a single extrastimulus （S1S2 ） at LA and RA. In the study, episodes of PAF were recorded and analyzed. Results The mean S1S2 interval induced 15 RAF was 130 ± 32 ms. With progressive shortness of S1S2, 18 AF happened at S1S2 of 110 ± 28 ms. Induction of AF was mostly preceded by RAF （66.7%）. In all, 15 RAF were induced in 14 dogs. RAF induced in LA were more than that in RA（ 11/14 vs 4/14, P 〈 0.05）. In addition, the incidence of AF was significantly higher in LA than in RA （12/14 vs 6/14, P 〈0.05）. Conclusion A RAF often precedes to the initiation of AF, which may be a useful marker of propensity to AF. Heterogeneity between LA and RA repolarization creates the different vulnerability between LA and RA. Atrial vulnerability in LA is higher than in RA.