射频导管消融犬左束支电位对心脏电机械活动的影响

目的 探讨射频导管消融犬左束支电位(LBP)对心脏传导及心功能的影响,以及犬左束支传导阻滞(LBBB)模型的制备方法.方法 应用射频消融导管在10只实验犬左心室内膜标测到LBP处进行消融,观察能否成功制备犬LBBB模型以及其对心脏传导的影响.对成功复制LBBB的模型犬应用超声心动图比较LBBB前后心脏收缩功能及舒张功能的变化.结果 10只犬接受LBP处消融后,8只(80％)成功制备LBBB模型.消融靶点处心房与心室电压比值＜1:10,局部记录的LBP至心室电位间期为17.1±3.2(12～22)ms,消融后QRS波宽度由52.8±4.8ms增至100.5±11.1ms(P＜0.001),而PR间期、AH间期、HV间期无明显变化.另外2只犬在LBP至心室电位间期分别为30ms、32ms处消融,导致完全性房室传导阻滞.8只犬发生LBBB后超声心动图检查示:收缩功能指标左室射血分数和主动脉血流速度积分降低(P＜0.05)；舒张功能指标E/A下降为＜1,伴有等容舒张时间和二尖瓣减速时间延长(P＜0.05)；出现显著室间与室内不同步,表现为间隔后壁运动延迟及左右心室射血前期时间差明显延长(P＜0.001).结论 射频导管消融左束支电位可导致LBBB,是制备犬LBBB模型成功率较高的方法,但有发生完全性房室传导阻滞的危险.LBBB即刻可导致左室激动延迟,左右室间及左室内收缩不同步,左心室收缩及舒张功能降低.

Effect of left bundle potential on cardiac electro-mechanical activity in dogs with radiofrequency catheter ablation

Objective To investigate the effect of left bundle branch potential(LBP) on cardiac conduction and function in dogs with radiofrequency catheter ablation,and explore method for reproducing left bundle branch block(LBBB) model in dogs.Methods LBP was mapped and ablated by radiofrequency catheter in the left ventricular endocardium in 10 dogs to observe whether LBBB model was prepared successfully.Echocardiography was performed before and after LBBB in the successfully-prepared LBBB models to study the systolic and diastolic function of left ventricle.Results After LBP ablation,LBBB was successfully created in 8(80%) dogs.Atrial and ventricular amplitude ratio(A:V) was less than 1:10 at successful ablation site and the interval of LBP to local ventricular potential(LBP-V) was 17.1±3.2ms(range from 12 to 22ms).The QRS duration was increased from 52.8±4.8ms to 100.5±11.1ms(P<0.001) after LBBB in these 8 dogs,but there were no significant changes in PR,AH and HV intervals after LBP ablation.In the remaining 2 dogs,a similar LBP potential was identified with LBP-V 30 and 32ms,but complete AV blocks were produced during or after RF energy application.In 8 LBBB dogs,echocardiography showed that systolic and diastolic functions all decreased,not only with reduced left ventricular ejection fraction(LVEF),aortic blood flow velocity time integral and E/A,but also with extended E wave deceleration time and isovolumetric relaxation time(P<0.05).Moreover,significant prolongation of septal-to-posterior wall motion delay and increased difference of pre-ejection time(P<0.001) denoted intraventricular and interventricular desynchronization after LBBB.Conclusion Radiofrequency catheter ablation of LBP could result in LBBB and might be an effective method for reproduction of canine LBBB model,although complete AV block might happen in few dogs.After LBBB,intraventricular and interventricular desynchronization and left ventricular electrical activation delay could immediately occur accompanied by decrease of cardiac systolic and diastolic functions.