What affects esophageal injury during radiofrequency ablation of the left atrium? An engineering study based on finite-element analysis

Abstract

Recent studies on intraoperative radiofrequency ablation of atrial fibrillation have reported some cases of injury to the esophagus. The aim of this study was to perform computer simulations using a theoretical model in order to investigate the effect of different factors on the temperature distributions in the esophagus during ablation. A three-dimensional model was built to include an active electrode, atrial tissue, epicardial fat layer and a fragment of esophagus, aorta and lung, all linked by connective tissue. The finite-element method was used to calculate the temperature distribution during a procedure of constant-temperature ablation. The lesion geometry was assessed using a 50 degrees C isotherm. Our results show that the electrical power directly applied to the esophagus is insignificant and hence the esophageal injury is exclusively due to thermal conduction from the atrium. The esophageal lesion is mainly influenced by the thickness of connective tissue. Both the programmed target temperature of the electrode and the duration of the ablation also have a significant effect on the lesion in the esophagus. In contrast, the epicardial fat layer (0.9 mm thickness) did not show a significant influence. In conclusion, this theoretical model allows us to study the effect of different factors on the thermal injury in the esophagus during intraoperative radiofrequency ablation of atrial tissue.

Esophageal Injury and Temperature Monitoring During Atrial Fibrillation Ablation

“…[11][12][13] A major limitation of this approach is that it fails to account for the variability in the thickness of the posterior LA wall and the presence of periesophageal connective tissue-important determinants of esophageal heating. 7,14,15 Thus, empirically limiting the power and duration of RF applications may be insufficient to prevent esophageal thermal injury in all patients. The aim of this study was to determine whether RF power delivery during AF ablation guided by luminal esophageal temperature (LET) monitoring is associated with less frequent esophageal injury compared with a strategy of power limitation alone.…”

“…Fourth, the distance between the left atria and the esophagus was not accounted for in this analysis. Although the total tissue thickness between the esophagus and LA is an important factor determining esophageal injury, 15 computed tomography analyses have suggested a close relationship of the posterior LA and esophagus in virtually all patients. 23 Moreover, adjusting for patient's body mass index did not result in any additional protection from esophageal ulceration.…”

Esophageal Injuries

“…Kardiyak aritmi, özellikle atrial fibrilasyon tedavisinde yapılan sol atrial radyofrekans (RF) ablasyonun özofa-gus hasarına yol açabildiği gösterilmiştir (15,16).…”

The Esophageal Temperature Probe: Helpful Monitoring Device or Inadvertent Amplifier of Risk?

“…4 Importantly, animal models suggest that these esophageal lesions are a form of thermal injury in that there is a linear relationship between the measured esophageal temperature and the frequency with which esophageal (and periesophageal) injury occurs as well as the size of individual lesions. 9,10 Over the past several years, investigators have reported on the merits of various intraprocedural interventions aimed at reducing the likelihood of inadvertent esophageal injury and thus an A-E fistula. These include some basic measures like reduction of energy when targeting the posterior LA wall or avoidance of lesions in this region and also techniques for real-time intraprocedural visualization of the esophagus, 11 11,13 monitoring the esophageal temperature during ablation using an intraluminal temperature probe, 7,11,14,15 cooling the esophagus during ablation, 16 and displacing the esophagus away from the site(s) of ablation.…”