Anatomical Characteristics,Radiofrequency Catheter Ablation Lesion Formation And Electrocardiographic Features Of Left Ventricular Summit And Its Adjacent Regions

Objective: To investigate the anatomical characteristics and radiofrequency ablation lesion formation of the left ventricular summit(LVS)and its adjacent regions by dissection and radiofrequency energy application.And to investigate the electrocardiographic characteristics of ventricular arrhythmias(VAs)originating from different parts in the continuum between the aortic sinus of Valsalva and the LVS by clinical research.Methods: 1.In-vitro experiment in the anatomical characteristics and radiofrequency catheter ablation lesion formation of LVS and the adjacent regions.Detailed dissection was performed on 12 in-vitro fresh swine hearts to collect and analyze the depth of myocardium and fat tissue,the adjoining structures of the left coronary cusp(LCC)and right-left interleaflet triangle(R-L ILT),and the distance between coronary vessel and the adjacent structures in the anterior interventricular groove and left atrioventricular groove.Radiofrequency energy was applied on different parts related to the LVS in 17 fresh swine hearts,including the right ventricular outflow tract(RVOT)endocardium,LCC,left ventricular outflow tract(LVOT)endocardium,accessible area of LVS,inaccessible area of LVS,great cardiac vein(GCV),and left ventricular anterior wall(LVAW).The incidence of steam pop and the lesion depths of myocardium were recorded and measured.2.Clinical research on the electrocardiographic characteristics of VAs arising from the continuum between the aortic sinus of Valsalva and the LVS Ninety-eight patients who underwent radiofrequency ablation for VAs and succeeded in the continuum between the aortic sinus of Valsalva and the LVS,including LCC,subLCC,aortomitral continuity(AMC),and GCV,in General Hospital of Northern Theater Command from January 2017 to November 2021 were retrospectively reviewed.The electrocardiographic characteristics as well as the baseline and procedural characteristics were analyzed.Results: 1.Characteristics of the anatomy and radiofrequency catheter ablation lesion formation in LVS and its adjacent regions 1)At the apex of LVS,the thickness of epicardial fat tissue and myocardium was 7.32±2.66 mm and 7.27±3.37 mm,separately.As the distance to the LVS apex increased,the thickness of epicardial fat decreased but the thickness of myocardium and left ventricular wall increased.2)In the anterior interventricular groove,the average distance was 3.32±2.29 mm between the anterior interventricular vein(AIV)and left anterior descending branch(LAD),and 9.98±2.28 mm between the RVOT endocardium and LAD.In the left atrioventricular groove,the average distance between left circumflex branch(LCX)and GCV was 2.80±1.51 mm,and the distances from LCX and GCV to the closest left atrium(LA)endocardium were 9.09±3.45 mm and 7.62±3.12 mm,respectively.3)There was fibrous tissue between the LCC and LV myocardium,of which the thickness was 1.51±0.82 mm.The RVOT was opposite to the R-L ILT,and the distance between them was 6.66±2.82 mm.The inferior transverse sinus was observed between the RVOT and RL ILT in 2 swine hearts.4)The incidence of steam pop was highest in the accessible area(17/39),followed by the inaccessible area(5/29),RVOT(3/35)and GCV(2/31).5)The radiofrequency ablation lesion depth of myocardium in the inaccessible area,accessible area,GCV and LCC was lower,compared to the LVAW,LVOT endocardium and RVOT endocardium.2.Electrocardiographic characteristics of VAs arising from the continuum between the aortic sinus of Valsalva and the LVS Among the 4 groups,GCV group had the longest operation duration and fluoroscopy time as well as the largest amount of X-ray exposure.Based on electrocardiographic analysis,there were significant differences between AMC or GCV group and LCC or subLCC group on the R-wave deflection interval in lead V1,V2,V3,the R-wave deflection interval differences between lead V1 and V2,the deflection index in lead V1 and R wave amplitude of lead Ⅱ.The R-wave deflection interval in lead V1≥85.5ms can identify AMC-or GCV-originated VA from LCC or sub-LCC ones with the sensitivity,specificity,positive predictive value and negative predictive value of 81.3%,77.3%,63.4% and 89.5%,respectively.Conclusions In the LVS,as the distance to the LVS apex increase,the thickness of epicardial fat decreases and the thickness of myocardium increases.The lesion depth of radiofrequency ablation in the epicardial side is lower than in the endocardial side,with higher incidence of the steam pop.It is helpful to understand the anatomical characteristics and lesion depth of the LVS to improve the safety and efficiency of clinical radiofrequency catheter ablation of ventricular arrhythmia.For VAs originating from the continuum between the aortic sinus of Valsalva and the LVS,the R-wave deflection interval in Lead V1≥85.5ms can predict the origin in AMC or GCV.