Fig 1.
Experimental setup with the distribution of materials used and measurements for later analyses.
(a) The data on the voltage (V [V]), current (I [mA]), power (P [W]) and time (t [s]) are recorded by the RFA equipment in .csv format. (b) The impedance curve parameters are calculated. (c) The indices δ, DR, and AR are estimated.
Fig 2.
This figure illustrates time and impedance parameters for an ex vivo bovine tissue ablation curve.
Fig 3.
The figure illustrates the thermal damage area obtained. The x and y axes were considered for volume calculation, with the z axis being perpendicular to the formed plane.
Table 1.
Summary of volumes obtained by each experimental group.
Fig 4.
This graph presents the impedance curves of each group for analysis.
Fig 5.
The positive sign of δ indicates two findings: 1—the curve is asymmetric, the procedure midpoint is not the minimum impedance point; and 2—the minimum impedance point is ahead of the RFA operating midpoint. In only two cases did the minimum impedance point occur before the half of experiment time (in the SALINE5 group).
Fig 6.
Correlation between performance index δ and volume.
The graph displays the correlation between volume in the groups and the index δ. The PURERF group shows weak evidence of a positive correlation. The SALINE5 group shows the highest evidence of negative correlation (R = -0.69 and p = 0.069).
Fig 7.
The group with saline solution at 5°C showed the only significant difference compared to PURERF group with a DR of 31.2% and 22.4%, respectively (p = 0.006).
Fig 8.
Correlation between DR performance index and volume.
The graph presents the correlation of the volume in groups to the DR index. The direct correlation is statistically significant in the DEI5 group.
Fig 9.
The AR index detects the variation between the minimum point of impedance to the point of occurrence of the first roll off. All experimental groups resulted in accentuated AR, except for SALINE23 with (167.7,48.4-549.4,mean,min-max,p = 0.002). Only SALINE23 showed a statistical difference, compared to the PURERF.
Fig 10.
Correlation between AR performance index and volume.
The graph presents the correlation between the volume in the groups and the AR index.
Fig 11.
Estimated marginal averages of the index δ.
The graph indicates no significant differences owing to the solution type or the temperature. Furthermore, there were no interactions between the factors.
Fig 12.
Estimated marginal averages of the AR indicator.
The graph indicates no significant interactions for the solution type or the temperature. The AR index decreases in both solutions when refrigerated. This indicates a lower final impedance.
Fig 13.
Estimated marginal averages of the DR indicator.
The graph shows the interaction between the solution type and temperature. An inverse behavior between the solution type is observed with the change in temperature. The saline solution allows for a higher impedance drop compared to RFA.
Table 2.
Estimated marginal averages of performance indices for groups DEI23, DEI5, PURERF, SALINE23 and SALINE5.
Table 3.
Estimated marginal averages of the performance indices for the factors solution type and temperature level.