Radiofrequency Ablation with an Enhanced-Irrigation Flexible-Tip Catheter versus a Standard-Irrigation Rigid-Tip Catheter

Background The flexible‐tip irrigated ablation catheter Cool Flex™ (St. Jude Medical, St. Paul, MN, USA) was introduced to enhance cooling of the catheter‐tissue interface and to conform to endocardial surface with better contact. Little is known about the performance of such catheter design compared to the widely used rigid‐tip catheters. Methods In a thigh muscle preparation, ablation using the flexible‐tip and rigid‐tip catheters was performed in seven pigs across a range of ablation settings and catheter orientation. Postprocedure, the thigh muscle was stained with 2,3,5‐triphenyltetrazolium‐chloride injected into the femoral artery. The muscle was excised, fixed with formalin, and examined grossly. Results A total of 196 lesions (95 flexible tip, 101 rigid tip) were evaluated. The flexible‐tip catheter was associated with enhanced cooling of catheter‐tissue interface (31.1 ± 3.3°C vs 36.3 ± 3.7°C, P = 0.0001) in both perpendicular and nonperpendicular catheter orientations. This allowed more energy delivery (37.3 ± 8.9 W vs 33.7 ± 8.1 W, P = 0.004) to targeted tissue and resulted in larger lesions (median 194.7 [interquartile range: 113.1–333.8] mm3 vs 170.9 [88.7–261.6] mm3, P = 0.03) than the rigid‐tip catheter with larger maximum diameter (11.1 ± 2.6 mm vs 10.3 ± 2.1 mm, P = 0.03) and larger diameter at tissue surface (10.3 ± 2.4 mm vs 9.6 ± 1.7 mm, P = 0.01). Catheter orientation during ablation affected the efficiency of rigid‐tip but not the flexible‐tip catheter. The use of the flexible‐tip catheter was associated with significantly less char formation on tissue (none vs 5.1% with rigid tip, P = 0.009). Conclusion The Cool Flex™ catheter performed better than a rigid‐tip catheter with enhanced cooling, larger ablation lesions, and no charring of targeted tissue.