Background—Ablation lesion depth caused by radiofrequency-based renal denervation (RDN) was limited to <4 mm in previous animal studies, suggesting that radiofrequency-RDN cannot ablate a substantial percentage of renal sympathetic nerves. We aimed to define the true lesion depth achieved with radiofrequency-RDN using a fine sectioning method and to investigate biophysical parameters that could predict lesion depth.Methods and Results—Radiofrequency was delivered to 87 sites in 14 renal arteries from 9 farm pigs at various ablation settings: 2, 4, 6, and 9 W for 60 seconds and 6 W for 120 seconds. Electric impedance and electrode temperature were recorded during ablation. At 7 days, 2470 histological sections were obtained from the treated arteries. Maximum lesion depth increased at 2 to 6 W, peaking at 6.53 (95% confidence interval, 4.27–8.78) mm under the 6 W/60 s condition. It was not augmented by greater power (9 W) or longer duration (120 seconds). There were statistically significant tendencies at 6 and 9 W, with higher injury scores in the media, nerves, arterioles, and fat. Maximum lesion depth was positively correlated with impedance reduction and peak electrode temperature (Pearson correlation coefficients were 0.59 and 0.53, respectively).Conclusions—Lesion depth was 6.5 mm for radiofrequency-RDN at 6 W/60 s. The impedance reduction and peak electrode temperature during ablation were closely associated with lesion depth. Hence, these biophysical parameters could provide prompt feedback during radiofrequency-RDN procedures in the clinical setting.

Background: Intravenous catheters are widely used but are often removed due to complications associated with catheter sleeve formation. A catheter sleeve can develop from a thrombus, and catheter-induced vascular endothelium damage may be a critical factor for thrombus formation. We investigated the effect of catheter-induced mechanical stimulation on venous endothelial cells and catheter sleeve formation and the efficacy of anti-thrombogenic technology for preventing catheter sleeve formation in vivo. Methods: We surgically implanted poly(2-methoxyethyl acrylate)-coated and uncoated catheters with and without a stylet into the right external jugular vein of a rabbit model for 14 days. Catheter sleeve formation and the ratio of residual venous endothelial cells were compared using histological examination and immunostaining with an anti-CD31 antibody, respectively. Results: Stiffening an uncoated catheter with a stylet induced catheter sleeve formation along more than two-thirds of the length of the catheter. The ratios of residual venous endothelial cells at the tip of uncoated catheters with and without a stylet were 3% and 36%, respectively. While poly(2-methoxyethyl acrylate) coating also reduced the ratio of venous endothelial cells at the tip of the stiffened catheter (12%), it prevented external thrombus and catheter sleeve formation. Conclusion: High levels of mechanical stimulation can affect catheter-related thrombosis and promote catheter sleeve formation, and anti-thrombogenic technology such as a poly(2-methoxyethyl acrylate) coating reduces thrombus formation and can prevent catheter sleeve formation on stiffened catheters. Further studies are required to determine the maximum degree of venous endothelial cell damage before catheter sleeve formation and to compare other anti-thrombogenic technologies with poly(2-methoxyethyl acrylate) for preventing catheter sleeve formation.

The level of endothelial coverage in BioPol-BES was comparable to BMS at four weeks, with no significant increase of inflammatory reaction up to 15 months.

Objectives: We first aimed to identify the histopathological changes occurring immediately after renal denervation (RDN) with radiofrequency energy, and then to assess the feasibility of determining procedural success using currently available clinical intravascular imaging techniques.Background: Catheter-based RDN has been used as an alternative therapy for hypertension.