PO-03-042 A COOL DRINK OF WATER: CONVECTIVE ESOPHAGEAL COOLING PREVENTS THERMAL INJURY FROM RADIOFREQUENCY HEATING IN AN EX VIVO SWINE ESOPHAGUS MODEL

Abstract

Esophageal heating and subsequent thermal injury are concerning adverse effects of radiofrequency (RF) energy ablation on the posterior wall of the left atrium. Active intraluminal esophageal cooling may provide thermal protection, allowing for effective delivery of RF energy to overlying myocardium without collateral damage to the underlying esophagus. To evaluate the impact of esophageal luminal cooling with a closed loop continuous flow irrigation on esophageal heating and thermal injury using an ex vivo model. A flexible tube was placed through the lumen of a swine esophagus and connected to a closed loop circuit consisting of a pump and water bath (Figure 1, panel A). The esophagus was submerged in a saline bath with a temperature of 36 °C and an impedance of 140 ohms. Ten non-contiguous RF lesions were delivered at 50 watts for 8 seconds directly on the outer esophageal wall with 4 mm irrigated RF ablation catheter. This was performed without irrigation (control), irrigation at 1.5 L/min with room temperature water (20 °C), and irrigation at 1.5 L/min with ice water (0 °C). Esophageal tissue samples were obtained from immunohistochemistry and the esophagus was cross sectioned and lesions were measured with digital calipers. Closed loop continuous flow esophageal irrigation with ice water yielded esophageal lesions with the smallest surface area (Figure 1, panel A), depth, and volume (Figure 1, panel B). Continuous esophageal irrigation with room temperature water resulted in the second smallest lesions. RF lesions without esophageal irrigation resulted in the largest and deepest lesion, as well as evidence of luminal esophageal injury (Figure 1, panel C & D). Histology showed preserved smooth muscle, glands, basement membrane and epithelium with cooled esophagus and transmural lesions with non-irrigated esophagus (Figure 1, panel C & D). Continuous endoluminal esophageal cooling reduced lesion size with RF energy delivery. There was no luminal injury with room temperature and ice water esophageal irrigation. Thus, both may be useful in prevention of endoluminal esophageal injury during poster wall RF ablation.