Continuous and discontinuous radiofrequency energy delivery on the atrial free wall: Lesion transmurality, width, and biophysical characteristics

Abstract

Background Although lesion transmurality is required for durable pulmonary vein isolation, excess ablation is associated with increased risk of complications. Objective We sought to understand the impact of interrupted radiofrequency (RF) delivery conditions on lesion characteristics in the atrial free wall. Methods Thirty-three (11 left atrial, 22 right atrial) RF ablation lesions were created in the atria of 6 swine using power control mode (25 W, target contact force 15 g) with 1 of 3 conditions: 15 seconds ablation (n = 8), 30 seconds ablation (n = 14), or 2 15-second ablations at the same site separated by a 2-minute interruption (15 seconds × 2) (n = 11). Results Thirty of 33 lesions were transmural. Rates of transmurality ( P = .45) and endocardial lesion width (5.6 ± 1.2 mm, P = .70) were similar between conditions. Mean tissue thickness was 1.7 ± 0.8 mm for transmural lesions. Wide variability in bipolar electrogram attenuation was observed across and within conditions and there were no significant between-group differences. Although impedance reductions were numerically greater in the 30-second and 15-second × 2 conditions (-14.6 ± 6.6 ohms and -14.0 ± 4.4 ohms, respectively) compared to the 15-second condition (-10.3 ± 6.4 ohms), variability was large, and differences were not statistically significant ( P = .243). Impedance changes after ablation were largely transient. Conclusion A single 15-second ablation at 25 W (target contact force of 15 g) with good stability produced similarly sized lesions compared to 30-second ablations and 2 15-second ablations at the same site in atrial free wall tissue. These data suggest over-ablation in the atria is common, larger-diameter lesions may require greater power, and many clinically available parameters of lesion size may be unreliable on the posterior wall.

Asymptomatic esophageal perforation following high-power short-duration pulmonary vein isolation—A case of conservative cure

“…In addition, LSI becomes visible after 6 seconds and is, therefore, often not helpful when HPSD protocols are used. At first notification, LSI is often already >4.5 (in many electrophysiological centers the target at the LAPW), 15 and shorter lesions will not show any LSI value at all (in the presented case 4 of 10 RF lesions [ Supplemental Table 1 ]).…”

Personalized pulmonary vein antrum isolation guided by left atrial wall thickness for persistent atrial fibrillation

“… 14 On the other hand, excessive RF delivery in thin regions of the left atrial (LA) wall is associated to increased complication rate. 15 …”