Experimental Study On The Influencing Factors Of Lesion Dimensions In Radiofrequency Catheter Ablation

Objective: To investigate the effects of ablation parameters such as base impedance,power,and irrigation rate on lesion dimensions with radiofrequency catheter ablation（RFCA）by different ablation catheters.Methods: Under the same ablation duration（15s）or different settings of AI（300,400,500,600）/LSI（4,5,6,7）,base impedance（90,120,150,180Ω）,power（30,40,50,60w）,irrigation rate（8,17,30ml/min）,RFCAs were performed on ex-vivo porcine left ventricle submerged in 36-37℃ half-normal saline（HNS）by Smart Touch^TM SF（ST-SF）catheter and Tacti Cath^TM Quartz（TCQ）catheter.Ablation duration,contact impedance,lesion dimension and other parameters were recorded and analyzed.Result: For 260 ablation lesions were performed.1.Both ST-SF and TCQ catheters were used for 15 s,the corresponding index AI value was 388.00±3.16 and the LSI value was4.06±0.17.The surface width of the ablation lesions in the two groups were（4.05±0.11 mm vs 3.97±0.42 mm,p=0.715）and maximum width（5.60±0.26 mm vs 5.51±0.58 mm,p=0.746）were not significantly different.However,the maximum depth was particularly greater with the ST-SF catheters compared to the TCQ catheters（2.02±0.11 mm vs 1.58±0.12 mm,p < 0.001）.2.AI/LSI showed positive correlations with the maximum width（r=0.967,p<0.001.r=0.910,p<0.001）and the maximum depth（r=0.974,p<0.001.r=0.956,p<0.001）.3.At a fixed AI value of 400,The smaller the baseline impedance,the larger the lesion dimensions（depth and width）.When LSI was 5,the lesion dimensions were not statistically different with the base impedance varies in 90-150Ω,but became larger in 180-210Ω.4.To reach target AI of 400,LSI of 5,the ablation power was positively correlated with the maximum width of lesions（r=0.811,p < 0.001.r=0.897,p < 0.001）,and the maximum depth was negatively correlated（r=-0.471,p =0.002.r=-0.673,p < 0.001）.With the increase of the ablation power,the ablation durations decreased（r=-0.948,p < 0.001.r=-0.906,p < 0.001）.5.There were no significant differences in the ablation lesion dimensions of the ST-SF catheters with different irrigation rates.For the TCQ catheters,irrigation rates were positively correlated with the ablation duration（r=0.665,p=0.008）,but negatively correlated with the maximum width and the maximum depth（r=-0.782,p<0.001.r=-0.789,p < 0.001）.For a given target AI/LSI,the maximum widths（STSF:5.91±0.10 mm vs 5.68±0.04 mm,p=0.001.TCQ:8.27±0.22 mm vs 7.51±0.40 mm,p=0.005）and the maximum depth（ST-ST: 3.63±0.07 mm vs 3.15±0.14 mm,p<0.001.TCQ:5.00±0.04 mm vs 4.25±0.03 mm,p<0.001）with 0.45%NaCl solution（semi-normal saline）for irrigation and were larger than that of 0.9%NaCl solution（normal saline）.6.AI was400,the contact angles between the ST-SF catheters and the tissues did not strongly affect the lesion dimensions.LSI was 5,the contact angles of TCQ catheter had negative impact on the maximum width（r=-0.946,p<0.001）and ablation duration（r=-0.816,p<0.001）.show negative correlation with the maximum depth（r=-0.832,p<0.001）.Conclusions: In the same ablation duration,ablation efficiency of the two kinds of catheters is different.In a definite range,the ablation lesion dimensions aiming a high AI/LSI are bigger.When the base impedance varied within a certain range,the ablation lesion dimensions of the TCQ catheter were not affected.For the ST-SF catheter,the smaller the baseline impedance,the larger the lesion dimensions.Generally,with the smaller lesions and shorter durations using higher power.Irrigation rate,which has no influences on the ablation lesion dimensions of the ST-SF catheters,is negatively correlated with the TCQ catheters.Compared with 0.9%NaCl solution,the lesion dimensions of the two kinds of catheters with 0.45%NaCl solution for irrigation and were larger.For the TCQ catheters,the greater contact angles,the wider the maximum width of ablation lesions.Whereas,the contact angles have no significant effect on the lesion dimensions for the SF-ST catheters.