Electroanatomical Mapping Characteristics Of Superior Vena Cava Muscle Sleeve And Induction And Ablation Study Of Superior Vena Cava Muscle Cuff-triggered Atrial Fibrillation

PART 1 Three dimensional electroanatomic mapping characteristics of superior vena cava myocardial sleeve and sinoatrial node in patients with atrial fibrillationObjectiveTo compare the electroanatomical characteristics of superior vena cava(SVC)myocardial sleeve and sinoatrial node(SAN)between patients with atrial fibrillation(AF)and those without by using three-dimensional electroanatomical mapping system(Carto3),as well as to provide the anatomical basis for the design of SVC isolation pathway and improve the safety of SVC isolation.MethodsOne hundred thirty six patients with AF who underwent radiofrequency catheter ablation for the first time in the first affiliated hospital of Nanjing medical university were selected as the study group,and 20 patients with premature ventricular contractions who had no history of AF and excluded structural heart disease were the control group.The right atrium(RA)and SVC three-dimensional anatomical activation model were constructed under sinus rhythm and the earliest of activation(EAA)of SAN was marked.The SVC and RA were discriminated with the RA-SVC junction as the boundary.The SVC was divided into anterior,lateral,posterior,and septal aspects and the RA was equally divided into high,middle and low parts in the right anterior oblique 30 degree position,respectively.The distal of SVC myocardial sleeve was defined as the absence of SVC potential at the proximal electrode and the presence of SVC potential at the distal electrode during the catheter manipulation from the cranial to caudal.The length of SVC myocardial sleeve was defined as the vertical distance from the distal of muscle sleeve to the RA-SVC junction.ResultsOf the 136 patients,93 were paroxysmal atrial fibrillation(PAF)and 43 persistent atrial fibrillation(Ps AF).The length of SVC myocardial sleeve in patients with PAF and Ps AF were no difference(39.4 ± 9.0 mm vs.40.5 ± 10.7 mm,P = 0.51).Among patients with AF,the length of myocardial sleeve in male was longer than that in female(42.1 ± 9.4 mm vs.35.4 ± 8.1 mm,P < 0.001).When the EAA was above the RA-SVC,the length of the SVC myocardial sleeve was longer than that below the EAA(P < 0.001).There were no significant correlation between the length of myocardial sleeve and the cardiac parameters including RA diameter,but a significant linear relationship between myocardial sleeve length and height(R = 0.43,P < 0.001).After adjusting for gender and weight,height was still a risk factor for SVC sleeve length.The length of myocardial sleeve was no difference between patients with AF and those without(39.8 ± 9.5mm vs.35.7 ± 8.5 mm,P = 0.07).64/136(47.1%)AF cases showed the EAA of SAN located below RA-SVC junction,of which 60(93.8%)were located in high RA and 4(6.2%)in middle RA with the average-8.9 ± 6.1 mm distance between the EAA of SAN and RA-SVC junction.The EAA of SAN was located above the RA-SVC junction in 72/136(52.9%)cases,including 46(63.9%)in the lateral wall,14(19.4%)in the anterior wall,8(11.1%)in the septal aspect and 4(5.6%)in the posterior wall.The mean distance between the EAA of SAN and the RA-SVC junction was 10.2 ± 4.7 mm.There was no significant difference between PAF and Ps AF in the spatial distribution of the EAA and the distance between the EAA and RA-SVC junction.13/20(65.0%)of non-AF patients whose the EAA of SAN were below the RA-SVC junction,of which 11(84.6%)cases were in high RA and 2(15.4%)in the median RA.The average distance between EAA and RA-SVC junction was-9.0 ±4.9mm.7/20(35%)of non-AF cases showed the EAA located above the RA-SVC junction,including 4(57.1%)cases in the lateral wall of SVC,2(28.6%)in the anterior wall,and 1(14.3%)in the posterior wall.The average distance between the EAA and the RA-SVC junction was 9.5 ± 6.2 mm.There was a trend of statistical difference in the distribution of the EAA of SAN and the relative distance between the EAA and the RA-SVC junction between non-AF patients and Ps AF subgroup.Conclusions1.There was no significant difference in SVC myocardial sleeve length between AF and non-AF,PAF and Ps AF patients.2.Those with the EAA in the SVC tend to have longer myocardial sleeve.3.There was no significant correlation between SVC myocardial sleeve and cardiac size in adults,but a linear correlation between myocardial sleeve length and height.4.Most of the EAA of SAN were located in SVC,especially in Ps AF patients.PART 2Induction and ablation of atrial fibrillation triggered by myocardial sleeves of superior vena cavaObjectiveTo investigate the trigger foci of superior vena cava(SVC)myocardial sleeves in patients with paroxysmal atrial fibrillation(PAF)by inducing atrial frbrillation(AF)before circumferential pulmonary vein isolation(CPVI),and to evaluate its possible predictive factors and assess the prognostic value of SVC ablation.MethodsSixty-eight patients with definitely diagnosed PAF undergoing AF radiofrequency catheter ablation for the first time referred to the first affiliated hospital of Nanjing medical university from December 2019 to April 2021 were evaluated prospectively.All patients were in sinus rhythm prior to procedure and received the standard induction protocol before CPVI.Intravenous infusion of isoproterenol increased basal heart rate by more than 20% and waited for 3 minutes.If no spontaneous AF induced,High frequency stimulation(Brust)from the coronary sinus ostium at cycle length(CL)of200 ms for 30-second were performed,twice repeated.If no AF presented,the same protocol was employed for stimulation regarding the second anatomical structure(SVC).If AF,was still not triggered,subsequently adenosine triphosphate 40 mg was allowed to be injected intravenously.If a patient was found inducible at the former stimulation attempt,no further stimulation attempt was performed.AF foci were determined position according to the earliest atrial potential or the initiation of ectopic P wave at the reference electrode.The SVC foci were defined as the atrial potential or the initiation of ectopic P wave inducing AF was the earliest in the SVC.All patients with SVC foci were treated with SVC ablation and CPVI.Patients with non-SVC foci were randomly divided into CPVI+SVC ablation or CPVI alone.ResultsThe induction rate of AF before CPVI was 66.2%(45/68).The inducible group had lower diastolic blood pressure(P < 0.001)and less ? receptor blocker utilization(P = 0.04)than the non-inducibile group.Multivariate binary logistic analysis showed that patients with lower diastolic blood pressure(OR [odds ratio]:0.90,95% CI[confidence interval]: 0.84-0.97,P=0.01)could predict AF inducibile.The foci of SVC were found in 19 out of 68 cases(27.9%).Compared patients with non-SVC foci,those with SVC foci were older(P = 0.02),lower body mass index(BMI)(P=0.04)and longer SVC myocardial sleeves(P=0.02).Univariate and multivariate binary logistic analysis showed that SVC sleeve length was an independent risk factor for SVC foci(OR:1.17,95%CI: 1.03-1.32,P = 0.02).Selective SVC ablation was performed in 18 out of 19 patients with SVC foci.Twenty-eight of forty-nine patients with non-SVC foci were performed SVC ablation.Either the selective SVC ablation group or the empirical SVC ablation group compared with the non-SVC ablation group,there was no significant difference in the proportion of sinus rhythm maintenance in the short term,but a trend of difference in the AF-free survival rate over time.Seven patients had recurrences at mean follow-up of 6.4 ± 4.2 months.Among them,4 patients were inducible,3 case were non-inducibile.Overall,the success rate of single procedure was 89.7%(61/68).Kaplan-Meier curve showed that there was no significant difference in short-term freedom of AF recurrence between inducibility and non-inducibility.Conclusions1.AF can be induced in 66.2% of patients with PAF before CPVI.The predisposition to AF inducibility was related to low diastolic blood pressure.2.The percentage of SVC foci was 27.9% and the length of SVC myocardial sleeve was an independent risk factor of SVC triggering AF.3.SVC ablation may affect the long-term prognosis of PAF.4.AF inducibility before CPVI was not associated with short-term AF at free survival.