持续快速肺静脉起搏对犬心房结构及心电生理特性的影响

目的探讨快速起搏肺静脉(PV)建立持续性心房颤动(房颤)犬模型的心房结构及心电生理特性。方法 30只犬随机分为实验组和对照组,实验组以20Hz的固定频率行肺静脉持续起搏,建立持续时间24h的房颤动物模型。超声心动图测量实验组基础状态和起搏结束后左右心房面积,对所有犬的左右心房游离壁、左上肺静脉、左下肺静脉、右上肺静脉和右下肺静脉进行心外膜电生理标测,测量各标测部位的有效不应期(ERP)和平均房颤波周长(AFCL),观察肺静脉起搏对心房面积的影响以及各部位ERP和AFCL的变化。结果实验组11只犬完成实验,在(28.2±3.0)d内诱发出持续超过24h的房颤。超声心动图测量显示起搏结束后心房面积明显扩大(P0.05);与对照组相比,左右心房及各肺静脉的ERP明显缩短(P0.05);实验组各部位ERP和AFCL呈明显的梯度分布,自短至长依次为:肺静脉、左房游离壁和右房游离壁。结论在犬快速肺静脉起搏房颤模型中,心房面积的增大及各部位电生理特性的变化可能是持续性房颤诱发和维持的发生机制。

Effects of persistent rapid pacing of pulmonary vein on electro-physiological charactaristics and atrial structures of canine

Objective To investigate the electrophysiological characteristics and atrial structures in the canine models of persistent atrial fibrillation （AF） prepared with rapid pacing of pulmonary vein.Methods Thirty canines were randomly divided into experimental group （n=15） and control group （n=15）.Canines in experimental group underwent persistent pacing of pulmonary vein （PV） at 20 Hz to induce AF model （24 h）.Biatrial areas were measured using two-dimensional echocardiography before and after rapid pacing of PV.Six mapping electrodes patches were used to record the electrophysiological characteristics of four PVs,left atrium （LA） and right atrium （RA）.Effective refractory period （ERP） and atrial fibrillation cycle length （AFCL） were also measured.Results Persistent AF （24 h） was successfully induced in 11 canines in experimental group within （28.2±3.0） d.At the end of the pacing period,biatrial areas were enlarged significantly 〔LA：（6.9±1.1） cm2 vs （11.7±1.6） cm2 （P0.001）;RA：（4.3±0.8） cm2 vs （7.0±1.2） cm2 （P0.001）,respectively〕.Compared with the control group,the ERP of atriums and four PVs in the experimental group were shortened significantly.There was also an ERP/AFCL gradient on different positions in experimental group after pacing.ERP/AFCL in the RA free wall was significantly longer than that in the PVs and LA free wall （P0.05）.Conclusion In canine model of persistent AF induced by rapid pacing of PV,the changes of electrophysiological characteristics and atrial structures may be involved in mechanism of persistent AF.