Search

Background: After catheter ablation there is often a discrepancy between acute and chronic success rates. We aimed to evaluate major determinants for lesion quality and understand different manifestations of lesion structures. Methods: In a canine thigh muscle model radiofrequency (RF) current was delivered for 60 seconds at 30 W (n = 39) or 50 W (n = 18) with 15-g contact force. A second-generation 12-hole gold open irrigation catheter (SGIT) and a first-generation six-hole platinum-iridium catheter (FGIT; Biotronik, Berlin, Germany) were used. Electrode and tissue temperatures (at the surface and 3.5-mm and 7-mm depth) were recorded and lesion dimensions were measured. Lesions with steam pops were excluded. Histological examination was performed to evaluate homogeneity of the lesions. Inhomogeneity was defined as a visual multiband lesion pattern indicating different histological characteristics. Results: In total 57 lesions were created. Seventeen lesions were excluded (steam pops) and 40 lesions were analyzed. A total number of 11 homogeneous and 29 inhomogeneous lesions were identified. Using the SGIT catheter 16.7% of the lesions was homogeneous and 83.3% inhomogeneous; for FGIT it was 43.8% and 56.2% (P = 0.065), respectively. Homogeneous lesions had lower volumes as compared to inhomogeneous lesions (514.0 +/- 198.8 vs 914.8 +/- 399.1 mm, P = 0.003). Multiple logistic regression analysis indicated that the SGIT catheter is a significant predictor for inhomogeneous lesions (odds ratio 6.5, 95% confidence interval 1.1-38.8; P = 0.040) independent from power setting and flow rate. Conclusions: The development of inhomogeneous lesions after acute RF ablation is associated with higher lesion volumes and the use of the second-generation irrigation gold-tip catheter.

BackgroundHigh irrigation rates during radiofrequency (RF) ablation may cause fluid overload and limit lesion size. This in vivo animal study assessed the safety and efficacy of RF ablation at low irrigation rates using a novel 12-hole gold catheter. MethodsA total of 103 lesions, created on the thigh of five mongrel dogs, were analyzed. Lesions were created using a 12-hole irrigated gold-tip (Au) and a six-hole irrigated platinum-iridium (PtIr) catheter (both 7F/3.5-mm electrode; BIOTRONIK SE & CO, KG, Berlin, Germany) in parallel and perpendicular orientation. RF current was delivered for 60 seconds at 30 W using 8mL/min and 15mL/min irrigation. Electrode temperature, steam pops, lesion dimensions, and coagulum formation were recorded. ResultsElectrode temperatures were lower for Au compared to PtIr in parallel (8mL/min: 38.1 1.7 degrees C vs 48.0 +/- 4.8 degrees C, P < 0.0001; 15mL/min: 36.0 +/- 1.5 degrees C vs 46.9 +/- 5.4 degrees C, P < 0.0001) and perpendicular position (15mL/min: 35.5 +/- 1.2 degrees C vs 38.4 +/- 2.5 degrees C, P= 0.003). The number of steam pops between Au and PtIr was comparable for parallel (8mL/min: 14% vs 27%, P= 0.65; 15mL/min: 14% vs 43%, P= 0.21) and perpendicular orientation (8mL/min: 25% vs 17%, P= 1.00; 15mL/min: 18% vs 0%, P= 0.48). Au created larger volumes than PtIr at 8mL/min irrigation (861 +/- 251mm(3) vs 504 +/- 212mm(3), P= 0.004); however, for 15mL/min, volumes were comparable (624 +/- 269mm(3) vs 768 +/- 466mm(3), P= 0.46). No coagulum formation was observed for any of the catheters on the surface and catheter tip. ConclusionRF ablation at low flow rate using a novel 12-hole irrigation Au catheter is safe and results in larger lesions than with a PtIr electrode.