右心房梗死伴左心房高频起搏诱发慢性房颤的电生理特性研究

Electrophysiological characters in a noble model of atrial fibrillation induced by left atrium pacing after right atrial infarction

目的:建立右心房梗死伴左心房高频起搏新型慢性心房颤动(AF)模型并探讨其电生理特性。方法:24只健康新西兰大白兔随机分为3组:对照组(C)、起搏组(P)、心房梗死+起搏组(I)。C组:在左心房外膜缝合固定一起搏电极,但不起搏;P组:在左心房外膜缝合固定一起搏电极并以1000beats/min的频率高频起搏;I组:结扎右冠状动脉心房分支,并在左心房外膜缝合固定一起搏电极,以1000beats/min的频率高频起搏。采用心外膜程序起搏技术测定心房肌的电生理特性。结果:(1)I组:起搏3周后AF诱发成功率高达100%。(2)I组、P组在起搏1h、1周、3周后心房有效不应期(ERPA)均缩短;I组、P组、C组:起搏3周后在基本起搏周期(PCL)200ms时的ERPA分别为(87.5±12.8)ms、(81.3±12.5)ms、(115.0±7.6)ms,I组、P组与C组比较,显著差异(P<0.01)。(3)在频率适应性方面,I组、P组均表现为频率适应不良,在术后3周时表现明显,与C组比较差异显著(分别P<0.01,P<0.05)。(4)I组在起搏3周后P波时限延长与P组、C组比较差异显著(P<0.05,P<0.01)。(5)I组:快速起搏后1h至3周,均表现为ERPA缩短、心房相对不应期(RRPA)延长与C组比较显著差异(P<0.01)、房间传导时间(IACD)延长与P组、C组比较显著差异(均P<0.01)。结论:右心房梗死+左心房高频起搏建立兔慢性AF与传统的单纯心房起搏相比,AF诱发成功率高并且稳定,其电生理参数有特征性意义,表现为ERPA缩短,频率适应不良,RRPA延长,IACD延长。

AIM： To explore a noble chronic atrial fibrillation model induced by left atrium pacing after right atrial infarction and to investigate the atrial electrophysiological characters of the model. METHODS ： 24 rabbits were randomly divided into 3 groups ： control group （ C group, n = 8）, pacing group （ P group, n = 8）, artial infarction ＋ pacing group （ I group, n = 8 ）. C group： a pacing pole was fixed under adventitia of the left atrium without pacing; P group： a pacing pole was fixed under adventitia of the left atrium with 1 000 beats/min of pacing; I group： the animals were placed under 1 000 beats/min of left atrial pacing after ligating the atrial branch of right coronary artery. The. technique of programmed stimulating was used to measure electrophysiological indexes of atrial in the groups. RESULTS： （ 1 ） After 3 weeks pacing AF was induced with a higher rates, and reached to 100% in I group. （2） At driving cycle length of 200 ms, ERPA was （115.0±7.6） ms in C group, （81.3±12.5） ms in P group and （87.5±12.8） ms in I group, which were statistically shorter in the later two groups compared to control group （ both P 〈 0. 01 ）. （3） I group and P group showed a significantly poor performance of frequency adaptability compared to control group after 3 week stimulation （ P 〈 0. 01, P 〈0. 05, respectively）. （4） 3 weeks after pacing, the interval of P - wave in I group was significantly prolonged compared to P group and C group （P 〈0. 05, P 〈0. 01, respectively）. （5） ERPA was obviously shortened and RRPA was prolonged significantly in I group compared to control group （P 〈 0. 01, respectively）. Interatrial conduction defect （IACD） was significantly prolonged in I group compared to C group and P group after 1 h to 3 week stimulation （P 〈 0. 01,respectively）. CONCLUSION： Compared to the traditional AF model induced by pacing only, a noble model of left atrium pacing after right atrial infarction has a higher AF incidence. The apparent electrophysiological changes of the AF model include： shortening of ERPA, the frequency inadaptability, extension of P -wave interval and prolonged RRPA as well as IACD.