Kolasa, Mark

Background: Current mapping systems use simultaneous displays of overlapping 3D maps and pre-acquired CT images of the LA to “pseudo-register” data sets rather than specifically “register” each point of one mapping data set to the other. The appropriateness of the 2 data set match has not been validated. Since significant surface to surface mismatch errors may occur, this study was undertaken to quanititatively validate NavX map to CT registration and determine its suitability for guiding AF ablation. Methods: Sixty-four slice, multidetector CT scans were acquired in 8 dogs and segmented to establish subject-specific LA/PV volumes for importation into the EnSite mapping system. A detailed multi-surface geometry (NavX map) was collected by navigating a mapping catheter in target LA and PVs. Using a novel developmental registration algorithm the map was registered to LA/PV CT volume. Validation was performed using the registered 3D CT model for the guidance of ablation at the location of multiple implanted radio-opaque markers. Results: A total of 39 radio-opaque markers were implanted before CT including 9 LSPV, 8 RSPV, 7 RIPV, 9 LIPV, 3 roof, and 3 LAA locations. Subsequent registration of individual NavX maps to acquired 3D CT volume was successfully completed in all animals. RF ablations were performed at the predicted 3D registered model locations of the radio-opaque markers using 5 mm tip RF ablation catheter. Resulting mean lesion size was 5.3 x 6.5 mm. The lesions enveloped the point of marker attachment to the myocardium in 31/36 (86%) ablations. The average distance from the center of the RF lesion to the targeted site was 2.5 ± 1.5mm. 47 points were successfully navigated under fluorscopic and ICE guidance. All points were accurately portrayed on the 3D registered model. 3 points in the region of the RSPV floor did have minor offsets on the model due to technically difficult segmentation of the RSPV from the right pulmonary artery. Conclusion: These data demonstrate the feasibility of registering NavX derived geometries to CT data sets accommodating sources of cardiac, respiratory, and translational cycle dependent error. Catheter navigation precisely conducted using the registered model demonstrates accuracy within the range required for RF ablation.

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.