Experimental Study Of Visualized Interventional Ultrasound Ablation Of Canine Kidney Sympathetic Nerve

Objective:To develop a visible intervention ultrasound ablation catheter (8.0 French) and test the imaging quality by observation of the renal sympathetic nerve in vitro condition, and to obtain the nerve ultrasonography character, to provide a basic for the in vivo imaging lately.Methods:The resolution power of ultrasound probe was evaluated by the gel platform, and the frequency and acoustic power of the ablation transducer was tested by the acoustic power meter. The imaging probe and ablation transducer were assembled into a single catheter, to form the visible intervention ultrasound ablation catheter. The catheter was inserted into the canine renal arteries in vitro, and the isolated renal nerves were imaged around the peri-arterial tissue. The tissue within the imaging range was removed and performed H&E staining, and compared with the ultrasound imaging.Results:The catheter profile was 8.0 F, with a 0-180°steerable tip, which had the abilities of high-frequency US imaging and acoustic ablation. The transverse and longitudinal resolution of the 64-elements probe was less than 300 μm, and the hyperechoic linear structure of the renal nerve could clearly provide. While compared with the histological sections of the imaging region, the hyperechoic and hypoechoic structures were indicated the epineurium and nerve fiber, respectively.Conclusion:This integrated catheter could meet the design requirement, which could clearly showed the renal nerve ultrasound structure in vitro, and provide a platform for the renal nerve ultrasonography and ablation in vivo.Objective:Using a visible intervention ultrasound catheter, to evaluate the feasibility and safety of RSN-ultrasound imaging based ultrasound ablation RDN in this study, to provide a more effectiveness and safety straetegy for the clincal denervation treatment.Methods:Under the X-ray guidance, the catheter was delivered to the distal end of the reanl artery (RA) in hypertension model canines (n=24), to provide renal-arterial nerve ultrasonography of the superior, ventral, inferior, and dorsal quandrant in the dital, middle and proximal RA segments, and the RSN number and innervation depth was recorded for analysis. In the RDN group animals (n=20), the arterial region received acoustic ablation using imaging-based site selection and the rest 4 animals underwent sham procedure. In the RDN group,4 animals were sacrificed 10 min post-ablation, while the rest and the sham group animals were sacrificed after 28 days for histological examinations.Results:All of animals survived the procedure. The renal nerves exhibited linear-like echoes, and the distribution densities varied RDN group,170 of the 256 ultrasonographically observed sites with higher nerve densities were selected for ablation. An average energy emission of 10.6 times was delivered to the bilateral renal artery. On 28 days post-ablation, the BP significantly decreased compared to the baseline (-12.6/9.1 mmHg, p<0.05) and to the sham group. The denervation effects were confirmed by pathological findings without significant US ablation-related complications.Conclusion:The ultrasound imaging-based RDN ablation can be safely and effectively achieved in this hypertensive canine model. Thus, the individualized strategy should be explored as a novel procedure for safer and efficient RDN in clinical practice.Objective:To probe the feasibility of the real-time renal denervation (RDN) treatment effective assessment using a visible intervention ultrasound (US) catheter, in order to provide a visible intra-operation treatment effective evaluation strategy for clinical RDN.Methods:Under X-ray guidance, the catheter was delivered to renal artery in the hypertension canines model, to provide renal sympathetic nerve (RSN) ultrasonography. in RDN group, the relative high nerve innervation arterial regions were selected for the US ablation (3.0×30s). the ultrasonographies of the ablation regions were recorded pre- and post-ablation for later analysis (Mean Intensity, and Entropy), and compared with the histological examination of target sites. The rest 2 animals were underwent a sham procedure. After the ablation, the RDN group animals were sacrificed for the histological examination in 5 min or 28 days post-ablation in Acute-RDN group and Subacute-RDN group, respectively.Results:The segmental distributed RSN were providing by the catheter. In RDN group, a total of 33 arterial regions were selected for the acoustic energy emission. Post the ablation, it showed macroscopic imaging change post-ablation, including the gray value of the linear structure enhancement, edge obscured and US parameter changes, including increasing of the Mean Intensity (23.52±6.62 vs.25.16±6.43, p<0.05), and Entropy (82.20±14.70 vs.86.59±14.81, p<0.05). The histological examination in the Acu-RDN group showed slightly edema and cavitation formed, while the target region showed an irrelative necrosis with the RSN after 28 days follow-up.Conclusion:The intra-operation real-time treatment effective evaluation of RDN could be achieved by the US observation of the target region using ultrasonography, which might provide a method for the clinical RDN treatment effective evaluation and increase the effectiveness of RDN.