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

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). Inter-atrial 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.