Mechanical Displacement
- Transesophageal Echocardiography
Mechanical displacement of the esophagus has been utilized with varied results. In a single center prospective nonrandomized study, a transesophageal echocardiogram (TEE) probe was used in 704 patients with remarkable findings: successful deployment and deviation of the esophagus in 680/704 patients (96%) with a mean displacement of 59 millimeters and complications of minor superficial bleeding in only 2/704 (0.3%)30. However, a subsequent study assessing displacement of the esophagus with a TEE probe reported contrary findings of being able to move the esophagus only 9.3 millimeters and the authors comment that the device tented the esophagus rather than displaced the entire segment31, meaning that the device did not move the trailing edge. Neither study utilized endoscopy post ablation.
- Gastroenterology Endoscope
Movement with use of a gastroenterology endoscope has been more successful32, with deviation of about 23 millimeters, but success was in only 10/12 patients (80%) and was performed by a physician with advanced training (endoscopist), thus interrupting workflow and requiring additional resources. However, because the results were modest, the need for subspecialist physician to perform the procedure simultaneous with performing an ablation procedure, and without movement of the trailing edge, this technique is not routinely utilized.
- Endotracheal Stylet
Another method used to deflect the esophagus has been reported using endotracheal stylets in 114 patients33. The stylet was easily placed and the mean distance of deflection was 14.6 millimeters, with rise in LET when the deflection was <5mm. Furthermore, one of the major limitations is that the trailing edge was not displaced leaving this section of the esophagus vulnerable to injury. This technique, however, has not been widely embraced since results are variable and use of stylets is a crude method that has not been validated in a multicenter study.
- Balloon Deviation
Another reported technique to deviate the esophagus is balloon deviation using the DV8 device34, which is a polyurethane device wrapped in silicone (Manual Surgical Sciences). Although the device is commercially available, it is not FDA approved.
As the device is inflated with air, the preshaped balloons result in increased esophageal pressure to a mean of 5 atmospheres (73 pounds per square inch, psi) and a maximum of 16 atmospheres (235 psi). The preshaped balloons deviate the esophagus in a predefined fashion according to the direction of the balloons, with a diameter of 17mm (Figure 2). The device is deflated, reinserted and re-inflated to move the esophagus in the opposite direction.
The device was tested in 200 patients undergoing AF ablation34. The study introduced the concept of measuring the mechanical esophageal deviation (MEDEffective), defined as the distance from the trailing edge of the esophagus to the ablation catheter, and correlated the MEDEffective to the change in LET. The MEDEffective was 18.4mm. Esophageal temperature increases occurred as MEDEffective decreased: 100% for MEDEffective ≤ 5mm, 43% for 5.1-10mm; 26% for 10.1-15mm; 23% 15.1-20; and 2% with >20mm. There were 2 complications of oropharyngeal bleeding.
Important limitations of the DV8 device is that the ideal deviation of >20mm was achieved in only 36% of patients, that balloon inflation within the esophagus is not easily adopted by electrophysiologists or anesthesiologists, the device does not provide varied degrees of deflection and the efficacy of deviation was not confirmed by post ablation endoscopy.
-Nitinol Retractor
Another device used for esophageal deviation during AF ablation that is commercially available but not FDA approved is the EsoSurepre-shaped nitinol retractor used in 209 patients35. This stylet is introduced through an 18Fr orogastric tube that is placed in the esophagus. At body temperature, the EsoSure device takes an ā€œSā€ shaped curve and hence deviates the esophagus (Figure 3). The study reported a significantly reduced occurrence of LET increase of >10C in patients with use of the stylet (3%), compared to a propensity matched control group (79%). The mean deviation was 25 millimeters. However, the presence of a trailing edge has been noted, there is no directional control and endoscopy has not been used to assess for post ablation lesions.
-Vacuum Suction
Another recently developed product for esophageal deviation that is not FDA approved is called Esolution. This device moves the esophagus using two techniques36. Through a central lumen of the device, a vacuum force is applied to the esophageal walls so the walls collapse upon the central core of the device. The central core consists of a mechanical arm which then can be deviated to the varied degree of control to the right or to the left. The vacuum suction applies a circumferential force that holds all walls of the esophagus so when the deflecting arm is used, the entire segment of the esophagus is deviated and the vacuum force eliminates the trailing edge (Figure 4). The device outer diameter is 11.6mm.
The first in man study was completed in 7 patients undergoing cryoballoon ablation37. The suction force was 200mmHg. The mean distance of deviation was 32mm to the right and 28mm to the left, and there was no trailing edge. Each patient was discharged the same day as the procedure and endoscopy was completed at a mean of 4 days post ablation. There was no esophageal lesion related to the device or to ablation energy. This device will undergo further evaluation with an upcoming FDA-approved trial comparing the occurrence of endoscopy-confirmed esophageal lesions post RFA in patients randomized to use of Esolution vs no deviation (EASY AF Study).