Increasing Power Versus Duration for Radiofrequency Ablation with a High Superfusate Flow:

Abstract

Radiofrequency (RF) ablation of pulmonary veins (PVs) is a new treatment for atrial fibrillation. Low energy ablation is usually used for this procedure. The effect of superfusate flow on lesion formation in this setting has not been studied previously. We examined lesion dimensions and intramural temperatures with varying powers and duration of RF application in this high flow environment. Ablation of fresh bovine hearts was performed with a 4-mm tip RF catheter in temperature control mode, target temperature 50 degrees C. At power levels of 20 W, 30 W, 40 W, and 50 W, effects of PV flow (no flow or 1 L/min) and 60- and 120-second durations were tested. Tissue temperatures were recorded at depths of 1, 4, 7, and 10 mm. Without flow, no lesions were created. The lowest power setting for lesion creation was 30 W at 60 seconds and 20 W at 120 seconds. Increasing power from 30 W to 50 W for 60 seconds increased lesion depth 0.7 mm (SE 0.3), P = 0.03 and 2.5 mm (SE 0.6), P = 0.003, at 120 seconds. Increasing RF application duration from 60 to 120 seconds increased depth for 30 W by 0.9 mm (SE 0.5), P = NS, 40 W 1.7 mm (SE 0.4), P = 0.002, and 50 W 2.6 mm (SE 0.5), P < 0.001. Power of 50 W for 60 seconds and >30 W for 120 seconds created lesions deeper than the wall thickness of a PV. Flow is necessary for creation of lesions with low power, low tip temperature RF ablation. When a resistant site to ablation is encountered, increasing duration of ablation is best for increasing lesion depth. Higher power has the potential to create lesions deeper than the PV wall and may increase the risk of complications.

Comparison of high‐power short‐duration (HPSD) ablation of atrial fibrillation using a contact force‐sensing catheter and conventional technique: Initial results

“…7,8 The factors that influence the formation of tissue injury, such as power, contact, local thermal heating (resistive and conductive), electrode diameter of the radiofrequency catheter, and lesion size and depth were modified over time, and the evolution of technologies that assimilate irrigated catheters and catheters with sensors that perform measurements in real-time, such as contact force information, were also modified. [9][10][11][12][13] 2 | OBJECTIVES The present study compared two different approaches to AFib ablation in consecutive patients undergoing a first ablation for AFib.…”

Update on high‐power short‐duration ablation for pulmonary vein isolation

“…Studies have been conducted to explore how the ablation lesion characteristics change with varying RF powers and duration. Early in 2003, Guy et al 7 performed the ablation of fresh bovine hearts at different power levels (20, 30, 40, and 50 W) and durations (60 and 120 s). Increasing power from 30 to 50 W for 60 s increased lesion depth 0.7 mm ( p = .03), and 2.5 mm ( p = .003) at 120 s; While increasing RF duration from 60 to 120 s increased depth for 30 W by 0.9 mm ( p = NS) and 50 W by 2.6 mm ( p < .001).…”

High‐power short‐duration ablation of atrial fibrillation: A contemporary review

“…Unfortunately, RF lesion formation is not always predictable in the clinical setting due to the variability in efficiency of energy coupling from the catheter electrode to cardiac tissue 11 . Evolution of irrigated‐tip catheters and CF sensing catheters have mitigated this variability and enabled delivery of higher power without excessive endocardial heating 5,6,12–14 . Development of CF sensing represents a significant milestone in optimizing efficiency and safety of RF ablation.…”

“…11 Evolution of irrigated-tip catheters and CF sensing catheters have mitigated this variability and enabled delivery of higher power without excessive endocardial heating. 5,6,[12][13][14] Development of CF sensing represents a significant milestone in optimizing efficiency and safety of RF ablation. CF catheters have demonstrated better longterm outcomes compared to non-CF catheters as seen in both SMART AF and TOCCASTAR when CF applied appropriately.…”