Open irrigation radiofrequency ablation resulted in significantly lower thrombus incidence compared to closed loop ablation (0% vs 50.8%, P<0.05) in a canine model.
Does open irrigation compared to closed loop cooling reduce thrombus and steam pop during radiofrequency ablation in a canine model?
Open irrigation during radiofrequency ablation provides superior interface cooling compared to closed loop systems, significantly reducing the incidence of thrombus and steam pops in a canine model.
Absolute Event Rate: 0% vs 50.8%
p-value: p=<0.05
BACKGROUND: Electrode cooling by circulating fluid within the electrode (closed loop) or open irrigation facilitates radiofrequency (RF) ablation. This study compared lesion parameters between closed loop and open irrigation with the use of a canine model. METHODS AND RESULTS: In 8 anesthetized dogs, the skin over the thigh muscle was incised and raised, forming a cradle superfused with heparinized blood (activated clotting time >350 seconds) at 37 degrees C. A 7F 4-mm closed loop electrode (irrigation 36 mL/min) and 7.5F 3.5-mm open irrigation electrode (irrigation 17 mL/min) were positioned perpendicular to the thigh muscle at 10 g contact weight. RF was applied (n=121) at 20 or 30 W for 60 seconds in low (0.1 m/s) or high (0.5 m/s) pulsatile blood flow. Temperatures were measured in the electrode, electrode-tissue interface, and within the tissue at 3- and 7-mm depths. After each RF, the cradle was emptied to examine the electrode and interface for thrombus. There was no difference between closed loop and open irrigation in impedance, lesion depth, or tissue temperature at 20 or 30 W. Interface temperature and electrode temperature were greater in the closed loop application. Thrombus occurred in 32 of 63 closed loop versus 0 of 58 open irrigation RF applications (P or =80 degrees C in all 32 (electrode temperature 50 degrees C in 5). With closed loop, interface temperature and thrombus incidence were greater at 30 W and low blood flow. With open irrigation, interface temperature remained low (< or =71 degrees C) with no difference between 20 and 30 W or between low and high blood flow. Steam pop occurred at 20 W in 4 of 35 closed loop and 0 of 30 open irrigation and at 30 W in 15 of 28 closed loop and 4 of 28 open irrigation applications (P<0.05). CONCLUSIONS: Lower interface temperature, thrombus, and steam pop, especially in low blood flow, indicate greater interface cooling with open irrigation.
Yokoyama et al. (2005) studied Radiofrequency ablation (n=8). Open irrigation electrode vs. Closed loop electrode was evaluated on Thrombus incidence (p=<0.05). Open irrigation radiofrequency ablation resulted in significantly lower thrombus incidence compared to closed loop ablation (0% vs 50.8%, P<0.05) in a canine model.