| ?Background and Objective? The mechanism and etiology of idiopathic right ventricular outflow tract premature ventricular contractions(PVCs)and ventricular tachycardia(VT)are not fully understood.There were few studies on the relationship between the two episodes.The sensitive and fast voltage mapping was shown a good correlation with biopsy and MRI on the assessment of myocardial fibrosis.,Endocardial unipolar votage mapping have more advantages than bipolar votage mapping in the identification of deep scars or epicardial scars.The purpose of this study was to explore the law of the ablation targets and the change of local substrate through the analysis on the target characteristics and local tissue voltage characteristics of unipolar voltage mapping and bipolar voltage mapping aroud the target(distance from 5mm,10 mm,15mm)in right ventricular outflow tract(RVOT)ventricular arrhythmias(VAs).?Methods? A total of 40 patients with idiopathic right ventricular outflow tract arrhythmias including PVCs group,28 patients and VT group 12 patients were enrolled in the study,5 patients with supraventricular tachycardia in the control group.Before the ablation,the CARTO system was applied to establish a detailed three-dimensional electroanatomic voltage mapping of RVOT during the sinus rhythm.The voltage on bipolar electrogram was defined as follows :partitioning criteria for endocardial voltage are: amplitude< 0.5 m V for ?the scar area?,amplitude between 0.5 and 1.5 m V as ?low voltage area(LVA)?,and amplitude?1.5m V for the normal voltage area.The voltage on unipolar electrogram was defined as follows: amplitude< 3.5 m V is the scar area,amplitude between 3.5 and 6.0 m V as?low voltage area?,and amplitude?6.0 m V for the normal voltage area.?Results? Both the control group and the study group showed a band-like LVA of similar size under the pulmonary valve annulus under bipolar electrogram.There was no significant difference in the distribution of the optimal ablation site between the VT group and PVCs group.The ablation target was 15% in the low voltage region(6cases/40 cases);42.5%(17 cases/40 cases)at the edge of the transition zone and42.5%(17 cases/40 cases)outside the low voltage zone.There was a significant difference between the 5mm inner area and other areas above ablation target to the unipolar voltage mapping or bipolar voltage mapping in study group.whereas only to the unipolar voltage mapping below ablation target.75% of ablation targets were in normal voltage area.And 75%(30/40 cases)in the septum;The electrogram of the ablation site were proceeding to 29.65±7.69 ms from the onset of the QRS complex during PVCs.In addition,The occurrence of fragmentation wave and voltage reversion in bipolar electrogram of oblationt catheter,as well as,the frustrated falling limb,W bottom and QS wave width >150ms of QS type in unipolar electrogram of oblationt catheter could be seen.The distance from the target to the pulmonary annulus with the bipolar electroanatomical mapping was 19.8 ± 10.9 mm,the nearest about 4 mm.?Conclusion? The majority originating sites of idiopathic RVOT arrhythmias were located in the LVAs,espcecially,the border between LVAs and the normal area.the matrix around the optimal target were the same to VT and PVCs,and there were focal micro-scarring around the ectopic origin.The unipolar electrogram is superior than the bipolar electrogram in terms of the identifation of the area and depth of LVA and scar area.The combination of unipolar maping and bipolar maping targets helps the successful ablation... |
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