The effect of half-normal saline irrigation on lesion characteristics in temperature-flow-controlled ablation.

Purpose: Radiofrequency (RF) ablation with half-normal saline (HNS) irrigation is reported to potentially enlarge local lesion compared to normal saline (NS) in power-controlled ablation (PC-Abl). However, the effect of HNS-irrigation in temperature-flow-controlled ablation (TFC-Abl) on lesion characteristics is unknown. We compared this between TFC-Abl with QDOT-Micro™ catheter and PC-Abl with Thermocool SmartTouch SF™ catheter (STSF). Methods: RF-application with NS (n = 480) and HNS (n = 480) irrigation were performed on swine myocardium placed in a circulating saline bath. Lesion characteristics without steam-pops under various conditions (target AI, 400/550; ablation power, 30/50 W; contact force, 10/20/30 g; catheter orientation, perpendicular/parallel) were assessed and compared between two irrigants. Results: After matching, 343 lesions without steam-pops in each group were evaluated. In PC-Abl, lesion size did not differ between two groups (NS, 188 ± 97 vs. HNS, 200 ± 95 mm³, p = 0.28 in volume; 33.9 ± 7.3 vs. 34.8 ± 9.5 mm², p = 0.34 in surface area; and 4.0 ± 1.0 vs. 4.0 ± 1.0 mm, p = 0.81 in depth), but steam-pops were more frequently observed with HNS-irrigation (23.8% vs. 37.9%, p = 0.001). Contrary, in TFC-Abl, HNS-irrigation produced significantly larger (214 ± 106 vs. 243 ± 128 mm³, p = 0.017) and deeper (4.0 ± 1.0 vs. 4.3 ± 1.1 mm, p = 0.002) lesions without increasing the risk of steam-pops (15.0% vs 15.0%, p = 0.99). Automatic temperature-guided titration was more frequently observed in HNS-irrigation (54.8% vs. 78.5%, p < 0.001). Conclusions: TFC-Abl with QDOT-Micro™ catheter utilizing HNS-irrigation might increase volume and depth of local lesion without increasing the risk of stem-pops compared to NS-irrigation. Power-controlled ablation with HNS-irrigation showed similar focal lesion with higher incidence of steam-pops (SPs) compared to normal saline (NS) irrigation. Contrary, temperature-flow-controlled ablation with HNS-irrigation provided larger and deeper lesion than NS-irrigation with similar incidence of SPs. ns, p > 0.05; *, 0.01 < p ≤ 0.05; **, 0.005 < p ≤ 0.01. HNS, half-normal saline; NS, normal saline. [ABSTRACT FROM AUTHOR]