Esophageal Luminal Temperature Measurement Underestimates Esophageal Tissue Temperature During Radiofrequency Ablation Within the Canine Left Atrium: Comparison Between 8 mm Tip and Open Irrigation Catheters

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Abstract
Evaluation of luminal temperature during left atrial ablation is used clinically; however, luminal temperature does not necessarily reflect temperature within the esophageal wall and poses a risk of atrioesophageal fistula. This animal study evaluates luminal esophageal temperature and its relation to the temperature of the external esophageal tissue during left atrial lesions using the 8 mm solid tip and the open irrigated tip catheters (OIC). A thermocouple was secured to the external surface of the esophagus at the level of the left atrium of the dogs. Luminal esophageal temperature was measured using a standard temperature probe. In four randomized dogs, lesions were placed using an 8 mm solid tip ablation catheter. In six randomized dogs, lesions were placed using the 3.5 mm OIC. The average peak esophageal tissue temperature when using the OIC was significantly higher than that of the 8 mm tip catheter (88.6 degrees C +/- 15.0 degrees C vs. 62.3 degrees C +/- 12.5 degrees C, P < 0.05). Both OIC and 8 mm tip catheter had significantly higher peak tissue temperatures than luminal temperatures (OIC: 88.6 degrees C +/- 15.0 degrees C vs 39.7 degrees C +/- 0.82 degrees C, P < 0.05) (8 mm: 62.3 degrees C +/- 12.5 degrees C vs 39.0 +/- 0.5 degrees C, P < 0.05). Both catheters achieved peak temperatures faster in the tissue as compared to the lumen of the esophagus, although the tissue temperature peaked significantly faster for the OIC (OIC: 25 seconds vs 90 seconds, P < 0.05) (8 mm: 63 seconds vs 105 seconds, P < 0.05). Despite the significant difference in actual tissue temperatures, no significant difference was observed in luminal temperatures between the OIC and 8 mm tip catheter.