## 4 Discussion  
### Main Findings  
This study comprehensively analyzed the ablation characteristics of the MEU and MEB modes of a CMC. A mapping catheter was used herein because of the commercial restriction on procuring regular CMCs for ablation research in China. We modified the mapping catheter to perform the ablation activity. The purpose of the experimental validation was to justify the ablation model by achieving a close agreement between the experimental and the simulation results; hence, the experiment environment and the ablation conditions were irrelevant. Apart from the many intrinsic deviations due to the anisotropic structure of the porcine tissue and the electrode contact, the dissimilarities in lesion morphology and temperature might be a consequence of the irregular shape of the porcine tissue and possible dissimilarity parameters of physical properties between the real and in silico myocardium. The large-scale expansion of the high-temperature field was partly deemed the creation of bubbles on the tissue surface during ablation, which were likely to be rather hot. The recordings from the thermal imager were also not accurate because of calibration and capturing a delay or potential deficiency. Above all, we believe that the experimental validation is reasonable, and our simulated modality is qualified for the comprehensive simulation research. Supplementary Figure S3 illustrates a standard ablation catheter from Biosense Webster [28], with three cases of simulation for its MEU and MEB performances. The simulation was performed based on a method like that described in Section 2.2. The MEU and MEB modes of the ablation catheter behaved in accordance with our previous findings, despite the different achievements of individual electrodes. Figure 8: Radiofrequency (RF) power generation and heat energy absorption by different material of the ablation model in the MEU and MEB modes during 60 s of RFCA. The morphology of lesion depth and the overall variation trend of maximum temperature were like those obtained before. As the dimension of the conventional ablation catheter is larger than the one employed in this study, it is reasonable that the maximum lesion depth is fully enlarged, whereas the maximum temperature of each active electrode is lower than the former model as a result of a higher current density over a smaller field for a fixed applied RF power. The dimensions of ablation catheters, such as PVAC and nMARQ, are distinct [11; 12]. However, we inferred from the comparison that the lesion features of the MEU and MEB modes are shared by all types of multielectrode ablation catheters to a large extent. The only uncertainty is in the variation of lesion size with the dimension and the number of electrodes, as well as the diameter of the helical CMC component of the CMC. Overall, the results of this study can meaningfully explain the lesion characteristics of the MEU and MEB modes. The simulation results show that it is difficult to achieve continuous lesions with the MEU mode on the tissue surface and high temperature, even with a relatively higher RF power. However, the MEU mode has a notable deep lesion path inside the myocardium because the current is guided to flow toward the dispersive electrode, which is situated at the bottom far from the active electrodes. Additionally, a broad and wide lesion volume in the MEU mode may have been caused by the large occupation of the dispersive electrode that directed the heat propagation in a wide radial path. The increase in lesion depth and volume may have been the effect of conductive heating, which transfers energy into the deeper tissue [29]. In regard to ablation outcome, the CMC cannot be operated purely in the MEU mode because its performance chiefly relies on the electrical and thermal conductivities of the media (from cardiac tissue to skin) and the distance between the active and dispersive electrodes.