肺静脉在犬持续性心房颤动维持中的作用

目的探讨快速起搏肺静脉建立持续性心房颤动(简称房颤)犬模型的电生理特性以及射频消融隔离肺静脉对其影响。方法选杂种犬15只,以20Hz的固定频率行肺静脉持续起搏,建立持续时间>24h的房颤的动物模型。对该模型的左、右房游离壁,左上、下肺静脉,右上、下肺静脉进行心外膜标测,测量各标测部位的有效不应期(ERP)和平均房颤波周长(AFCL)。对肺静脉电隔离,观察电隔离前后房颤的诱发以及各部位ERP和AFCL的变化。结果11只犬完成实验,在28.2±3.0d内诱发出持续超过24h的房颤。肺静脉电隔离前,ERP和AFCL分布呈明显的梯度分布,自短至长依次为:肺静脉,左、右房游离壁;肺静脉隔离后,8只犬转变为窦性心律,3只犬先转变为房性心律失常后,在60min内转变为窦性心律,再进行快速心房起搏刺激仅能诱发出小于60s的阵发性房颤,各部位ERP和AFCL也明显延长(P<0.05)。结论肺静脉的快速电活动可能在持续性房颤的维持中起关键作用。

Role of pulmomary veins in the maintenance of persistent atrial fibrillation in canines

Objective To investigate the electrophysiological characteristics in the persistent atrial fibrillation(AF)model of canines with chronic rapid pulmonary vein pacing and the changes of electrophysiological characteristics using radiofrequency(RF)to ablate the pulmonary veins of the models.Methods Fifteen mongrel dogs underwent chronic pulmonary vein(PV)pacing at 20 Hz to induce sustained(>24 h)AF.Six mapping electrodes patches were used to record the electrophysiological characteristics,including four PVs,left atrium(LA)and right atrium(RA).RF was applied around the PVs until the electrical activity was eliminated.Effective refractory period(ERP)and atrial fibrillation cycle length(AFCL)were measured before and after the ablation of PVs.Results Persistent AF(>24 h)was induced in eleven of fifteen canines within 28.2±3.0 days.During sustained AF,the shortest AFCL /ERP was located on LSPV in 9 dogs and RSPV in 2 dogs.AFCL /ERP in the RA free wall was significantly longer than that in the PVs and the LA free wall(P< 0.05).AFCL /ERP in the PVs was the shortest.After ablation,8 dogs converted to sinus rhythm,and 3 dogs converted to atrial arrhythmia first,then converted to sinus rhythm within 60 minutes.Rapid atrial pacing afterward induced only nonsustained(<60 s)AF in all dogs.ERP and AFCL after re-induction were significantly(P<0.01)longer than baseline.Conclusion These findings suggest that PVs are important in the maintenance of AF in dogs.