| Research backgroundThe formation of persistent myocardial tissue transmural injury is the key to improve the success rate of radiofrequency catheter ablation for tachyarrhythmia.Contact force between the catheter tip and the myocardial tissue has been validated to be one of the major determinants of lesion size in many experimental studies.The inadequacy of contact force between the ablation catheter tip and the myocardial tissue may be one of the important reasons leading to failure or recurrence of radiofrequency ablation procedure.On the other hand,excessive contact force may induce mechanical damage to the heart muscle or steam pops,leading to serious complications such as cardiac perforation and acute cardiac tamponade.A novel contact force sensing ablation catheter can accurately assess the contact force between the ablation catheter tip and the myocardial tissue in real time.The efficacy and safety of using contact force sensing ablation catheters in complex atrial arrhythmias represented by atrial fibrillation have been validated by many clinical studies.More than 90%of idiopathic ventricular arrhythmias originate in the outflow tract region of the ventricle,especially in the right ventricular outflow tract.Up to now,the clinical application of contact force sensing ablation catheters in the ablation of idiopathic ventricular arrhythmias originated from the right ventricular outflow tract(RVOT-VAs)is still rarely reported.Moreover,the range of effective and safe contact forces that need to be maintained for ablation within the RVOT remains unclear.Part?A retrospective investigation of cases with ventricular arrhythmia treated by radiofrequency catheter ablation.Objective:This study aimed to retrospectively investigate the clinical features,surgical outcomes,and safety of patients with VAs undergoing catheter radiofrequency ablation in our hospital,and to analyze the independent factors affecting the efficacy and safety of radiofrequency ablation of ventricular arrhythmia.Methods:Patients undergoing catheter ablation for ventricular premature contractions or ventricular tachycardia at the First Affiliated Hospital of Guangxi Medical University from January 2013 until October 2016 were included in our retrospective survey and analysis.After removing the cases to be excluded according to the exclusion criteria,the clinical data such as gender,age,height,weight,disease course,and underlying diseases,and the surgical data of the surgeon,ablation target sites,procedure time,surgical efficacy,and complications were extracted.The statistical analysis and evaluation were made on factors such as age,basic diseases,cardiac function indicators,and ablation targets that might affect the efficacy and safety outcomes.And a multivariate statistical analysis was performed on the factors that may affect the efficacy and safety of surgery.Results:A total of 435 patients were included in this retrospective study,including 334 patients with frequent PVC and 101 patients with persistent VT.The results showed that 69.6%of VAs cases were successfully ablated in ventricular outflow tracts,and 86%of them were successfully ablated in RVOT.The acute success rate of radiofrequency ablation,the recurrence rate,and the single-procedure success rate for VAs patients was 86.4%,14.1%,and 74.3%respectively,while the complication rate was 3.4%.Those independent factors that might affect the single-procedure success rate in patients with VAs included organic heart disease(OR=4.005,p<0.001)and the operator's experience(OR=0.599,p=0.003).Moreover,the free wall origin was one of the independent risk factors affecting the success rate of single procedure in patients suffered from RVOT-VAs(OR=5.182,p<0.001).Those independent factors that might affect the complication rate in patients with VAs included the operator's experience and body mass index.Conclusion:RVOT is the most common site of origin of idiopathic VAs.The operator's experience is one of the most important independent factors affecting the efficacy and safety outcomes of radiofrequency ablation in patients suffered from VAs.Part? A clinical case-control study of treating idiopathic ventricular arrhythmias originated from the right ventricular outflow tract using contact force sensing ablation catheters.Objective:This study aimed to explore the efficacy and safety of catheter ablation of idiopathic right ventricular outflow tract arrhythmias(RVOT-VAs)using contact sensing ablation catheters.Methods:Clinical control studies initially explored the efficacy and safety of contact force sensing ablation catheters in idiopathic RVOT-VAs.Patients with idiopathic RVOT-VAs who were eligible for radiofrequency catheter ablation were included.In the contact force catheter(CFC)group,Thermo Cool SmartTouch saline irrigated catheters were used for radiofrequency ablation,in non-contact force catheters(NCFC)group,radiofrequency ablation were performed with saline irrigated catheters without contact force sensing function.The success rate,single-operation success rate and recurrence rate of the two groups were recorded and compared.A multivariate statistical analysis was performed on the factors that may affect the efficacy and safety of surgery.The regional ventricular voltages and impedances measured in the RVOT using different contact force levels were recorded and compared in the CFC group.Results:In this clinical controlled study,92 patients with idiopathic RVOT-VAs were included,including 77 patients with frequent PVC and 15patients with persistent VT.The results showed that the single-procedure success rate in the CFC group was significantly higher than that of the NCFC group(93.6%vs 77.8%,p=0.029),and the reoperation rate was lower(p=0.048).The comparison results of acute success rate,recurrence rate and complication rate between the two groups showed no statistical difference.Multivariate analysis suggested that those independent factors affecting the single-procedure success rate include the application of contact force catheters,and the target site located in the free wall.The CFC group presented a lower number of ineffective ablations with shorter total procedure time(p<0.001),while the X-ray exposure time and dose in the CFC group were lower too(p<0.05).With the gradual increment of contact force,the regional ventricular voltage and impedance also increased accordingly(p<0.001).Conclusion:The efficacy and safety of radiofrequency ablation of idiopathic RVOT-VAs using contact force catheters are non inferior or even better than non-contact force catheters,and contact force catheters are helpful for shortening procedure time,decreasing ineffective ablation,and reducing X-ray exposure.Part? An animal experimental study on the effect of contact force at the tip of ablation catheter on the ablation lesion size of right ventricular outflow tract.Objective:This study aimed to evaluate the impact of contact force on the lesion formation during ablation in the right ventricular outflow tract(RVOT)of experimental swine,and to explore the safe and effective contact force range and to provide a theoretical basis for safer and more effective application of radiofrequency ablation for RVOT-VAs.Methods:Twelve Guangxi Bama miniature male pigs weighing 40 to 50kg were studied.After general anesthesia,all pigs were intubated and then mechanically ventilated with oxygen.ThermoCool SmartTouch contact sensing ablation catheter was introduced to RVOT via the femoral vein under the guidance of CARTO 3 electroanatomic mapping system.Three to four points were choosed in the free wall and septum of RVOT,four different contact force levels(3-9g,10-19g,20-29g,and 30-39g)were applied in order at each point.The local ventricular voltage and impedance measured in the RVOT using different contact force levels were recorded and compared.We randomly divided the animals into four groups according to different contact force levels:Group A(3-9g);Group B(10-19g);Group C(20-29g);Group D(30-39g).Three Bama pigs were included in each group.In each group,radiofrequency ablations were performed at three points in the free wall and septum of RVOT respectively.The radiofrequency ablation parameters were kept constantly during ablation discharge and set as follows:power control mode,radiofrequency power 30w,saline irrigation rate 17ml/min,and duration of ablation discharge 30s.The thoracotomies were performed,and the hearts were removed from the experimental animals at the end of the procedures.The maximum depth,surface diameter and lesion volume were measured and recorded,the relationship between contact force and lesion size was evaluated.Results:In this study,72 ablation lesions were created in the RVOT of the12 Bama pigs,of which 36 lesions were distributed in the free wall and 36lesions were distributed in the setum.The results showed that the maximum depth,surface diameter and volume of lesions in RVOT correlated well with contact force when the radiofrequency power,time and irrigation rate remained constant.When the septum was ablated,the volume,maximum depth,and surface diameter of the ablation lesion in the four groups A,B,C,and D were positively correlated with the contact force.However,when the free wall was ablated,despite the volume,maximum depth,and surface diameter of the ablation lesion in the groups A,B and C were positively correlated with the contact force,the maximum depth and volume of lesions in group D were similar to group C.Regional ventricular bipolar voltage,unipolar voltage,and impedance were weakly positively associated with contact force(R~2=0.141,R~2=0.113,R~2=0.166,p<0.001).The incidence of a steam pop increased significantly with increasing contact force(p<0.001),and the steam pop occurred only when contact force exceeded 20g.The transmural lesions were found when contact force exceeded 10g at the free wall,while lesions at septum were non-transmural even when the contact force attained 30g.Conclusion:The lesion size in RVOT correlated well with contact force between the distal end of ablation catheter and myocardial tissue when the radiofrequency power,time,and irrigation rate remained constant.Keeping the contact force in the range of 3 to 20g may be effective and safe. |
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