Effect Of Radiofrequency Catheter Ablation Of Left Bundle Potential On Cardiac Electrical And Mechanical Functions In Canines

ObjectiveTo explore the effect of radiofrequency catheter ablation of left bundlepotential (LBP) on cardiac conduction and mechanical function in canines and tocreate left bundle branch block (LBBB) model of the canines by RF catheterablation.MethodsLBP was mapped and ablated by radiofrequency catheter in the leftventricular endocardium in10canines. Echocardiography was performed beforeand after LBBB in the successful LBBB models to study the systolic and diastolicfunction of left ventricle.ResultsAfter LBP ablation, LBBB was successfully created in8(80%) canines. Atrialand ventricular amplitude ratio(A:V) was less than1:10at successful ablationsite and the interval of LBP to local ventricular potential (LBP-V) was17.1±3.2ms(range from12to22ms). The QRS duration increased from52.8±4.8ms to100.5±11.1ms (P<0.001) after LBBB in these8canines, but there were nosignificant changes in PR interval, AH and HV intervals after LBP ablation. In the remain2canines, a similar LBP potential was identified with LBP-V30and32ms, but complete AV blocks were produced during or after RF energy application.In8LBBB canines, echocardiography showed that systolic and diastolicfunctions were all decreased not only with reduced left ventricular ejectionfraction,reduced aortic blood flow velocity time integral and E/A, but also withextended E wave deceleration time and isovolumetric relaxation time (P<0.05）.Significant prolongation of septal-to-posterior wall motion delay and theincreased difference of pre-ejection time (P<0.001) showed intraventricular andinterventricular desynchronization after LBBB.ConclusionRadiofrequency catheter ablation of LBP could result to LBBB and might bea effective method in canine LBBB model preparation，although the complete AVblock might happen in few canines. After LBBB, intraventricular andinterventricular desynchronization and left ventricular electrical activation delaywere immediately occurred companied with decreased. cardiac systolic anddiastolic functions.