Limitations of Esophageal Temperature-Monitoring to Prevent Esophageal Injury During Atrial Fibrillation Ablation

Abstract

A number of complications have been associated with ablation of atrial fibrillation (AF), including arterial thrombo-embolism, pulmonary vein stenosis, phrenic nerve injury, and pericardial tamponade. [1][2][3][4] Esophageal injury, manifested as esophageal perforation or left atrial-esophageal fistula, has been reported after catheter or surgical ablation of AF using radiofrequency (RF) current 5-8 and catheter ablation using high-intensity focused ultrasound (HIFU). 9 Left atrial-esophageal fistula usually is associated with a very high morbidity and mortality, including air embolism and sepsis. Article see p 162Esophageal injury during RF ablation in the left atrium is thought to be thermal injury. 10 -12 In this issue of Circulation: Arrhythmia and Electrophysiology, Singh et al 13 sought to determine whether the risk of esophageal injury would be reduced by measuring the luminal esophageal temperature (LET) during ablation and maintaining the LET below 38.5°C. The LET was measured using a 9Fr flexible temperature probe (with a single thermocouple) in the esophagus. The temperature probe was maneuvered in cranial-caudal direction to position the thermocouple close to the ablation catheter tip in the left atrium.We agree in principal with the authors' conclusion that esophageal temperature-monitoring may reduce the risk of esophageal injury during AF ablation. An esophageal ulcer was observed by endoscopy 1 to 3 days postablation in 4 of 67 (6%) patients with LET-monitoring (and discontinuing RF application at LET Ն38.5°C) compared to 5 of 14 (36%) patients without LET-monitoring. Importantly, in patients with LET-monitoring, this study showed no significant difference between patients with and without an esophageal ulcer and the maximum LET during ablation or the number of RF applications producing an increase in LET to Ն38.5°C. This study did not identify a safety LET cut-off, below which an esophageal ulcer would not occur. There was also no relationship between the average RF power and the maximum LET.The lack of relationship between the LET and the occurrence of esophageal ulceration in this study may relate to the inability of currently available probes (a single thermocouple within the esophagus) to locate and measure the highest esophageal temperature during left atrial ablation. This problem was identified in a canine model of esophageal injury where RF, HIFU, and cryo-ablation were performed in the left atrium adjacent to the esophagus. 12,14,15 An air-filled balloon (20 to 25 mm diameter) was positioned in the esophagus to move the esophagus close to the posterior left atrium. Temperature was measured along the esophageal balloon by 7 thermocouples (2 mm separation) facing the left atrium and the ablation catheter. Esophageal ulceration occurred consistently when the maximum LET was Ն49.6°C for RF energy and HIFU energy. 12,14 Lower LET was not associated with ulceration. During cryo-ablation, esophageal ulceration occurred consistently when the minimum LET was Յ1.3°C. 15 Esophageal ulceration was...

Factors Associated With Periesophageal Vagal Nerve Injury After Pulmonary Vein Antrum Isolation

“…A strong relationship between an esophageal temperature rise and pain has been shown by prior study . Use of a proton pump inhibitor might facilitate ulcer healing and prevent the progression from esophageal injury to an atrioesophageal fistula . In contrast, PNI was observed in 7.9% of the patients during the period when 25 to 30 W were applied to the posterior LA, suggesting that the periesophageal vagal nervous system was much more fragile than the esophagus itself to thermal injury.…”

“…22 Use of a proton pump inhibitor might facilitate ulcer healing and prevent the progression from esophageal injury to an atrioesophageal fistula. 23,24 In contrast, PNI was observed in 7.9% of the patients during the period when 25 to 30 W were applied to the posterior LA, suggesting that the periesophageal vagal nervous system was much more fragile than the esophagus itself to thermal injury. This complication was not observed after a reduction of power only at specific small areas of the posterior LA where the ablation line transversed the esophagus (Figure 2, yellow points).…”

2012 HRS/EHRA/ECAS expert consensus statement on catheter and surgical ablation of atrial fibrillation: recommendations for patient selection, procedural techniques, patient management and follow-up, definitions, endpoints, and research trial design

“…Although left atrial-esophageal fistulae are rare (occurring after <0.1-0.25% of AF ablation procedures) [386,420,506,549], injury to the esophagus is common following AF ablation. In several clinical studies, endoscopy performed 1-3 days after AF ablation using RF energy, HIFU, laser balloon, or cryothermia identified an asymptomatic esophageal ulcer (directly behind the LA) in 4-60% (generally 15-20%) of patients [282,428,432,[580][581][582][583][584][585][586][587][588]. The asymptomatic esophageal ulcers were usually healed on repeat endoscopy at 2-3 weeks following treatment with a proton pump inhibitor and a cytoprotective agent such as sucralfate [583,586].…”

Steerable esophageal thermometer for atrial fibrillation ablation in a patient with esophageal achalasia: a case report

“…They mentioned that a possible mechanism of this result might be an "antenna effect" of the metallic tip of the catheter; that is, direct thermal injury from the temperature probe, whereas this remains controversial [12,13]. We set the upper limit of the esophageal temperature at 40°C during the procedure as a safety margin because it has been reported that setting it at less than 40-41°C was associated with a lower complication rate of esophageal injury [5,7,14]; however, there is no clear cutoff value for the temperature setting to avoid esophageal thermal injury [8,15]. As a result, this case achieved a successful AF ablation without any esophageal complications using the Esophastar â .…”