An Insight to the Role of Thermal Effects on the Onset of Atrioesophageal Fistula: A Computer Model of Open-Irrigated Radiofrequency Ablation.

Purpose: Atrial fibrillation (AF) is the most common heart rhythm disorder in the world. Radiofrequency catheter ablation (RFCA) has become the preferred method of treatment for drug-refractory AF. One of the rare (< 0.2%) but deadly (≈ 80%) complications of RFCA is Atrioesophageal fistula (AEF). Although the exact pathophysiological events in developing AEF are not fully understood, one hypothesis is that the underlying cause may be thermal damage to the mucosa (the esophagus lumen).

Method: The present study reports on a computer model of RFCA in the posterior wall of the left atrium (LA) which is in close proximity to the esophagus. A novel systematic approach was taken by considering a range of anatomical variations (obtained from clinical data) to study the spatial and temporal temperature data when RF energy was applied to cause a threshold temperature of 50 °C in the mucosa. The model is also used to investigate the spatial and temporal changes in mucosal temperature that may affect the reliability of the readings from esophageal temperature monitoring devices if they are not positioned accurately.

Results: The results suggest evidence of transmural esophageal lesions in all the anatomies except one, if the 50 °C temperature threshold is the only criteria used for identification of thermal damage. However, by taking into consideration the effect of time (temperature-time integral), only some anatomies were identified as being partially damaged. Investigating the temperature and the temperature gradient data during the ablation revealed that the increases in both the temperature and the temperature gradient were time, location and anatomy dependent. This finding may have significance in the design and development of next-generation temperature monitoring devices that will provide a temperature map rather than single point measurements.

Conclusion: Studies such as the present work may provide more convenient platforms for investigating the effect of the many factors involved in the RF procedure and how they may link to the development of AEF.