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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。
Objective To investigate the effects of radiofrequency catheter ablation of left bundle branch (LBP) on cardiac conduction and cardiac function in dogs and the preparation of left bundle branch block (LBBB) model in dogs. Methods Radiofrequency ablation catheter was used to measure the LBP in 10 experimental dogs. The LBBB model and its effect on cardiac conduction were observed successfully. Echocardiography was used to compare the changes of cardiac systolic and diastolic function before and after LBBB. Results After the LBP was ablated in 10 dogs, LBBB model was successfully established in 8 rats (80%). The ratio of atrial to ventricular voltage at ablation target was <1:10, and the local recorded interval between LBP and ventricular potential was 17.1 ± 3.2 (12-22) ms. After ablation, the QRS wave width increased from 52.8 ± 4.8 ms to 100.5 ± 11.1 ms (P <0.001), but there was no significant change in PR interval, AH interval and HV interval. The other two dogs in LBP to ventricular potential interval were 30ms, 32ms ablation, leading to complete atrioventricular block. The LBBB echocardiography in 8 dogs showed that the indexes of left ventricular ejection fraction and aortic flow velocity were decreased (P <0.05); the indexes of diastolic function E / A decreased to <1, accompanied by isovolumetric relaxation (P <0.05). There was significant interventricular and indoors asynchrony, which showed delayed posterior wall motion and prolonged left ventricular ejection time (P <0.001). Conclusion Radiofrequency catheter ablation of left bundle branch leads to LBBB, which is a method of preparing LBBB model with high success rate. However, there is a risk of complete atrioventricular block. Immediate LBBB can lead to delayed left ventricular activation, left ventricular and left ventricular contraction is not synchronized, left ventricular systolic and diastolic function decreased.