Early and Delayed Alteration of Atrial Electrograms Around Single Radiofrequency Ablation Lesion

Abstract

Purpose: The acute effect of radiofrequency (RF) ablation includes local necrosis and oedema. We investigated the spatiotemporal change of atrial electrograms in the area surrounding the site of single standardized pulse of RF energy.Methods: The study enrolled 12 patients (45–67 years, 10 males) with paroxysmal atrial fibrillation (AF) undergoing ablation procedure with irrigated-tip ablation catheter and 3D navigation. The high-density mapping/remapping (129 ± 63 points) within the circular area with radius of ~10 mm, centered at the pre-specified posterior left pulmonary vein antrum ablation site was performed at baseline, immediately after single RF energy delivery (25 W, 30 s, 20 ml/min) and after 30 min waiting period. Bipolar voltages of atrial electrograms (A-EGM-biV) were averaged within the central and 12 adjacent left atrium segments and their relative change was studied.Results: After the ablation, overall A-EGM-biV within the mapping zone (3.51 ± 1.89 mV at baseline) reduced to 2.83 ± 1.77 mV (immediately) and to 2.68 ± 1.58 mV (after 30 min waiting period). In per-segment pair-wise comparison, we observed highly significant change in A-EGM-biV that extended up to the distance of 8.8 mm from the lesion core. The maximum early A-EGM-biV attenuation by 39–49% (P < 0.001) was registered in segments adjacent to pulmonary vein ostia. The subsequent (delayed) A-EGM-biV reduction by 17–24% (P < 0.05) was observed in opposite direction from the lesion center.Conclusions: Significant alteration of atrial electrograms was detectable rather distant from the central lesion. Spatiotemporal development of ablation lesion was eccentric/asymmetric. While acute A-EGM-biV reduction can be attributed predominantly to direct thermal injury, delayed effects are probably due to oedema progression.

Irrigated DiamondTemp catheter and return to ablation under temperature control. First Polish experience with DiamondTemp catheter in pulmonary vein isolation.

“…In high power ablation the best method for the assessment of lesion efficacy is the change in electrogram (ECG) voltage. The duration of the application should be about 3.0-5.0 sec longer than potential disappearances or is significantly reduced (at least 75-80%) [8,19] (Fig. 10).…”

Improved One-year Outcomes After Active Cooling During Left Atrial Radiofrequency Ablation

“…[15] The authors propose explanations for these ndings that include the stacking of heat from prior ablation with sequential ablation, and the development of localized edema after lesion placement, resulting in impaired lesion formation with delayed lesions, while noting that edema formation is time dependent and may impede the recording of local electrograms and, thus, may play a greater role with increased temporal delay between lesions. [15,[17][18][19][20][21][22] As such, these ndings provide insight regarding possible mechanisms by which sequential ablation with minimal interruption has been associated with improved ablation outcomes. [23] Active esophageal cooling is performed without the need for temperature sensors, as the esophageal cooling device maintains a coolant temperature of 4 °C, and reduces the potential for esophageal wall temperatures to reach lethal isotherm levels.…”