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  •    Identification and Importance of Esophageal Injury after Radiofrequency Ablation for Atrial Fibrillation.
    Subba Reddy Vanga, MBBS AF News Bureau, JAFIB.

    Radiofrequency catheter ablation (RFA) as a potentially curative in the treatment of symptomatic and drug-refractory atrial fibrillation (AF) and is already included into the ACC/AHA/ESC 2006 Guidelines for the Management of Patients with AF [1]. As a very rare but potentially fatal left atrio-esophageal fistulae were formed from collateral damage resulting from the heat energy from RFA were described in early case reports [2-4]. This nearly fatal complication accounted for nearly 15% of deaths resulted from RFA procedures for AF [5]. Although the incidence of the fistula is less than 1%, high mortality adds significance to the problem. Thin atrial wall resulting from atrial enlargement (>60 mm in diameter), female patients, higher energy settings, cachectic patients, who are likely to have a thin left atrium wall with very little tissue between the left atrium and the esophagus were suspected culprits for development of fistula [2]. A nation-wide survey concluded that the risk of atrio-esophageal fistula is < 1%. However, atrio-esophageal fistula is associated major cerebrovascular events and leads to death in >80% of the patients [6]. In this survey all atrio-esophageal fistulae were associated with the use of 8mm tip ablation catheter.

    Typical patients who developed left atrio-esophageal fistula presents with features of pericarditis, fever and neurological symptoms such as stroke or convulsions 2-3 days after the procedure [7]. Multiple cardiac and cerebral emboli complicate the later phase and patients may or may not develop massive hematemesis. Widespread gaseous or septic embolization will continue without prompt surgical intervention as the fistula acts as the source of entry point for GI organisms. Diagnosis of the fistula requires high suspicion and an immediate CT of chest with water soluble contrast may demonstrate pneumomediastinum and/or fistulae. Invasive methods such as transesophageal echocardiography or gastroesophagoscopy should be avoided because, if a fistula is present, instrumentation of the esophagus may cause rapid deterioration and death [2, 4]. To prevent the collateral damage to esophagus during RFA, various techniques were developed. Esophageal luminal temperature monitoring [8], transverse displacement of esophagus [9], visualization of esophagus with barium [10] or Intracardiac echocardiography [11] are few methods that were studied before.

    Thermal injury to esophagus can result in destruction of tissues in anterior wall and result in altered function before a full blown fistula is formed. Auerbach's and Meissner's plexus can be damaged from heart energy resulting in myriad of symptoms ranging from esophageal motility disorder to increased acid reflux from altered lower esophageal sphincter tone. Similarly, damage to Vagus nerve which lies in close proximity to esophagus can alter gastric, pancreatic secretions and gastric motility. Upper GI endoscopic studies early after RFA have identified esophageal ulcers consistent with direct thermal injury to the esophagus in 3% to more than 20% of patients and ulcers healed almost always [12-14]11 L. Di Biase, L.C. Saenz and D.J. Burkhardt et al., Esophageal capsule endoscopy after radiofrequency catheter ablation for atrial fibrillation: documented higher risk of luminal esophageal damage with general anesthesia as compared with conscious sedation, Circ Arrhythm Electrophysiol 2 (2009), pp. 108–112. Full Text via CrossRef | View Record in Scopus | Cited By in Scopus (1). Thus, esophageal injury is relatively common, but rarely leads to fistula formation. One postulated mechanism involves injury to the esophageal vasculature that leads to an ischemic lesion that progress to fistula [15]. A two-hit phenomena, initial thermal injury followed by progressive lesion enlargement promoted by reflux of stomach acid bathing the lesion, was proposed as alternative which was supported by animal studies by Yokoyama et al [16].

    Recently two studies attempted to identify the extent of esophageal injury using two different methods. Badger et al used primarily non-invasive technique of the delayed-enhancement MRI of esophagus to identify the esophageal injury [17]. Martin et al investigated the incidence of esophageal ulcerations in patients undergoing RFA and studied the lesion sets and anatomical information given by multi-slice CT imaging with the development of esophageal ulcerations [18].

    Badger et al studied 57 patients who are undergoing RFA for AF. All patients underwent MRI scan 3 times during the study period, before the ablation, within 24 hours and at 3 months after ablation. 41 patients were finally analyzed after excluding the patients with uninterruptable studies. None of them had enhancement before ablation but 5 (12%) patients developed within 24 hours. All patients subsequently had resolution at 3 months. The results demonstrated that esophageal injury can be detected as regions of esophageal delayed gadolinium enhancement on MRI. This modality has the potential to noninvasively identify patients who have esophageal injury and track healing of these lesions over time.

    Martin et al studied 275 patients undergoing RFA for AF. Endoscopy was performed in every patient the day after the RFA procedure. Multi-slice CT scan was used to measure the distances between left atrium and esophagus and LA dimensions. 6 (2.2%) patients developed esophageal ulcers and all of them healed with proton pump inhibitors and H2 blockers by days. Persistent AF, performing additional lines of ablation LA enlargement and LA to esophagus distance are the significant risk factors. Surprisingly, the symptoms did not correlate the development of esophageal ulcerations.

    Conclusions: Esophageal lesions associated with the AF ablation procedure are often transient and asymptomatic and heal without consequence. Non-invasive techniques such as delayed enhance MRI scan can be used to determine the esophageal injury after RFA. The study also indicates that delayed enhancement MRI has the ability to detect and monitor progression of esophageal lesions after catheter ablation of AF. Acute esophageal injury or inflammation may manifest as esophageal ulceration in the immediate post ablation state with resolution of the findings by later follow-up. The risk factors for development of esophageal ulcerations are the LA size, distance between LA and esophagus, and set of ablation lines.

    Possible Impact on Clinical Practice: Methods for detecting esophageal injury are of interest to help identify esophageal injury and develop methods to reduce risk, but early detection of esophageal injury has to this point required endoscopic examination. The new non-invasive technique may be used in suspected patients and for serial follow-up. The risk factors identified in the study may provide an opportunity to prevent the esophageal ulcers by appropriate management. Most patients with esophageal ulcers were asymptomatic and universal post ablation acid suppression may be of benefit in healing those asymptomatic ulcers. More studies on the function of esophagus and upper gastrointestinal tract functions may provide more insights into the impact of RFA on esophagus.

    References:

    1. Fuster, V., et al., ACC/AHA/ESC 2006 Guidelines for the Management of Patients with Atrial Fibrillation: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Revise the 2001 Guidelines for the Management of Patients With Atrial Fibrillation): developed in collaboration with the European Heart Rhythm Association and the Heart Rhythm Society. Circulation, 2006. 114(7): p. e257-354.

    2.  Sonmez, B., et al., A fatal complication due to radiofrequency ablation for atrial fibrillation: atrio-esophageal fistula. Ann Thorac Surg, 2003. 76(1): p. 281-3.

    3. Mohr, F.W., et al., Curative treatment of atrial fibrillation with intraoperative radiofrequency ablation: short-term and midterm results. J Thorac Cardiovasc Surg, 2002. 123(5): p. 919-27.

    4. Gillinov, A.M., G. Pettersson, and T.W. Rice, Esophageal injury during radiofrequency ablation for atrial fibrillation. J Thorac Cardiovasc Surg, 2001. 122(6): p. 1239-40.

    5. Pappone, C., et al., Atrio-esophageal fistula as a complication of percutaneous transcatheter ablation of atrial fibrillation. Circulation, 2004. 109(22): p. 2724-6.

    6. Ghia, K.K., et al., A nationwide survey on the prevalence of atrioesophageal fistula after left atrial radiofrequency catheter ablation. J Interv Card Electrophysiol, 2009. 24(1): p. 33-6.

    7. Stollberger, C., T. Pulgram, and J. Finsterer, Neurological consequences of atrioesophageal fistula after radiofrequency ablation in atrial fibrillation. Arch Neurol, 2009. 66(7): p. 884-7.

    8. Cummings, J.E., et al., 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. J Cardiovasc Electrophysiol, 2008. 19(6): p. 641-4.

    9. Ejima, K., et al., Transverse shifting of the esophagus according to the patient's position helped achieve a safe and successful pulmonary vein isolation procedure. Heart Vessels, 2009. 24(4): p. 317-9.

    10. Ruby, R.S., et al., Prevalence of Fever in patients undergoing left atrial ablation of atrial fibrillation guided by barium esophagraphy. J Cardiovasc Electrophysiol, 2009. 20(8): p. 883-7.

    11. Helms, A., et al., Real-time rotational ICE imaging of the relationship of the ablation catheter tip and the esophagus during atrial fibrillation ablation. J Cardiovasc Electrophysiol, 2009. 20(2): p. 130-7.

    12. Martinek, M., et al., Esophageal damage during radiofrequency ablation of atrial fibrillation: impact of energy settings, lesion sets, and esophageal visualization. J Cardiovasc Electrophysiol, 2009. 20(7): p. 726-33.

    13. Singh, S.M., et al., Esophageal injury and temperature monitoring during atrial fibrillation ablation. Circ Arrhythm Electrophysiol, 2008. 1(3): p. 162-8.

    14. Di Biase, L., et al., Esophageal capsule endoscopy after radiofrequency catheter ablation for atrial fibrillation: documented higher risk of luminal esophageal damage with general anesthesia as compared with conscious sedation. Circ Arrhythm Electrophysiol, 2009. 2(2): p. 108-12.

    15. Sanchez-Quintana, D., et al., Anatomic relations between the esophagus and left atrium and relevance for ablation of atrial fibrillation. Circulation, 2005. 112(10): p. 1400-5.

    16. Yokoyama, K., et al., Canine model of esophageal injury and atrial-esophageal fistula after applications of forward-firing high-intensity focused ultrasound and side-firing unfocused ultrasound in the left atrium and inside the pulmonary vein. Circ Arrhythm Electrophysiol, 2009. 2(1): p. 41-9.

    17. Badger, T.J., et al., Initial experience of assessing esophageal tissue injury and recovery using delayed-enhancement MRI after atrial fibrillation ablation. Circ Arrhythm Electrophysiol, 2009. 2(6): p. 620-5.

    18. Martin, M., et al., Identification of a high Risk Population for Esophageal Injury during Radiofrequency Catheter Ablation of Atrial Fibrillation: Procedural and Anatomical Considerations. Heart Rhythm, 2010.


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