Contact force distribution and the value of contact force catheter during pace-map in right ventricular outflow tract

Backgrounds Whether the contact force(CF)-sensing catheter could improve the efficiency of pace mapping(PM)in right ventricle outflow tract(RVOT)has not been fully studied.The present study was the first investigation of the CF distribution in the right ventricle(RV)by using a CF-sensing catheter and the relationship between CF and capture threshold in RVOT.Methods In total,4543 mapping points with CF were recorded in 15 patients.Operators were blinded to CF data and data were analyzed according to 10 predefined RV segments.PM were performed at 6 different RVOT segments with 3 different intentional CF levels and 3 different pacing setup.The pacing threshold in RVOT and pacing capture level were recorded.The morphology matching score were recorded and analyzed.Results Median CF during RV mapping was 8(5-12)g and coefficient of variation was 71.64%.Median CF ranged from 9.5(5.8-16)g at the posterior-outflow tract freewall(OTFW)to 7(4-10)g at the apex.Distribution of CF≥20 g in RV predefined segments mainly located in the OTFW.Distribution of CF≤2 g in RV predefined segments mainly located in the inflow tract freewall(ITFW),anterior-OTFW,and apex.A total of 810 pacing were performed at RVOT with different CF and output.Stable capture rate could be significantly improved via increasing CF level under 2 mA output(46.7%/2-5 g vs.50%/6-9 g vs.91.1%/≥10 g),and no capture rate could be significantly declined simultaneously(16.7%/2-5 g vs.8.9%/6-9 g vs.2.2%/≥10 g).Conclusions A marked variability in CF was observed among the different predefined segments.CF mapping could improve the safety and efficacy of catheter ablation of premature ventricular contraction(PVC)/ventricular tachycardia(VT)in RV.CF was an essential factor in RVOT pace mapping process,especially under low-pacing output.[S Chin J Cardiol 2021;22(1):21-29]