Comparative Study of Lesions Obtained through Radiofrequency between the Irrigated Ablation Catheter with a Flexible Tip and the Non-Irrigated Catheter in Ex Vivo Porcine Hearts

Abstract

Background: At the same conditions of delivered power and contact force, open-irrigated radiofrequency ablation catheters are believed to create deeper lesions, while non-irrigated ones produce shallower lesions. This ex vivo study aims to directly compare the lesion dimensions and characteristics of an irrigated ablation catheter with a flexible tip and a non-irrigated solid-tip catheter.

Methods: Radiofrequency lesions were induced on porcine myocardial slabs using both open-tip irrigated and non-irrigated standard 4 mm catheters at three power settings (20 W, 30 W, and 40 W), maintaining a fixed contact force of 10 gr. A lesion assessment was conducted including the lesion depth, depth at the maximum diameter, and lesion surface diameters, with the subsequent calculation of the lesion volume and area being undertaken.

Results: Irrigated catheters produced lesions with significantly higher superficial widths at all power levels (3.8 vs. 4.4 mm at 20 W; 3.9 mm vs. 4.4 mm at 30 W; 3.8 mm vs. 4.5 mm at 40 W; p = 0.001, p = 0.019, p = 0.003, respectively). Non-irrigated catheters resulted in significantly higher superficial areas at all power levels (23 mm² vs. 18 mm² at 20 W; 25 mm² vs. 19 mm² at 30 W; 26 mm² vs. 19 mm² at 40 W; p = 0.001, p = 0.005, p = 0.001, respectively). Irrigated catheters showed significantly higher values of lesion maximum depth at 40 W (4.6 mm vs. 5.5 mm; p = 0.007), while non-irrigated catheters had a significantly higher calculated volume at 20 W (202 µL vs. 134 µL; p = 0.002).

Conclusions: Radiofrequency ablation using an irrigated catheter with a flexible tip has the potential to generate smaller superficial lesion areas compared with those obtained using a non-irrigated catheter.

Keywords: ablation; arrhythmia; irrigated catheter; lesion characteristics; radiofrequency.

Figure 1

Experimental Setup. The ablation catheter was carefully placed perpendicularly to the myocardial surface using a manipulator. A high-precision digital scale was placed under the chamber. Inside the saline chamber, a pump generated the non-pulsatile flow towards the ablation electrode–tissue interface. The ablation radiofrequency generator continuously monitored the applied voltage, current, power (1 to 100 W), impedance (50 to 300 Ohms), and temperature (set at 60 °C for the 4 mm catheter and 43 °C for the irrigated catheter). The current was applied in a unipolar mode between the distal electrode of the catheter and an indifferent lead placed underneath the myocardium (though not directly on it).

Figure 2

Irrigated ablation catheter with a 4 mm laser-cut flexible tip.

Figure 3

Lesion patterns with an irrigated catheter. The top row displays three slabs with RF lesions created using the irrigated catheter at 40 W. The second row shows slabs with RF lesions at 30 W, and the third row depicts slabs with RF lesions at 20 W using the irrigated catheter.

Figure 4

Lesion Characteristics. (A) Lesion depth, (B) maximum length of the lesion at any depth, (C) depth at the maximum length, and (D) lesion surface diameters (length and width: D1 and D2). In the upper and lower parts of the image, cross-sections of the RF lesion are depicted; in the center to the right, the endocardial superficial scheme of the lesion is shown with the highlighted length (D1), width (D2), and superficial area (green lines).

Figure 5

Comparison of lesion characteristics. Blue bars depict lesion characteristics obtained using the irrigated catheter, while orange bars represent those obtained using the non-irrigated catheter. Panel (A): histograms illustrating the maximum lesion depth at different power levels. Panel (B): histograms illustrating the maximum lesion length at different power levels. Panel (C): histograms illustrating the maximum lesion volumes at different power levels. Panel (D): histograms illustrating the maximum lesion superficial area at different power levels.