Abstract 4648: Mechanism of Tissue Cooling With Cryoenergy Delivery to Pulmonary Veins: Tissue Temperature Distribution and Chonic Esophageal Effects
Background: Although pulmonary vein (PV) isolation has been used to treat AF, complications create important limitations. New energy sources, including cryothermal, have been developed to minimize these complications. The purpose of this study was to evaluate the effect of PV cryoablation on esophageal (ESO) temperatures acutely and correlate them with chronic effects on the esophageal wall.
Methods: A 23 mm cryoballoon was placed in the LA of 10 dogs through a 12 Fr deflectable sheath. PV and ESO temperatures (TEMP) were recorded using 7–9 thermocouples (TC) outside the PVs and on the external and internal ESO surfaces during 2 cryoablations of 4 min duration.
Results: Cryoablation of 15 PV (10 RIPV and 5 LIPV) during 1.7±0.6 ablations yielded a total of 168 TC time-TEMP profiles (6.4±2.4/PV). Minimum tissue TEMP was inversely dependent on the distance of the TC from the balloon surface (Table 1⇓). All PVs were isolated acutely and 14/15 (93%) chronically. Minimum TEMP achieved at the PV surface and external ESO were similar (−32±8 and −37±9 at targets within 2.5 mm from the balloon respectively [P=NS]). A TEMP decrease at the internal ESO was seen during 15 of 25 (60%) ablations, but was significantly less pronounced than the external TEMP (17.9°C±13.3 and 6.1°C±24.8 [p<0.05]) resulting in a minimum recorded internal TEMP of −6.2°C. The ESO histological examination in 5 dogs showed very limited external lesions in these dogs (depth= 2.2±1.1, width3 18.6±7.4 and length= 12±5.7 mm), but no transmural or internal ulceration, fibrosis or scarring seen.
Conclusion: Although PV cryoablation decreases external ESO temperature and produces minor lesions, significant chronic disruptive tissue damage was not seen. Esophageal injury is an unlikely, but potential complication of cryoablation, with internal temperature proving unhelpful in predict negative outcome.