Percutaneous Translumial Renal Nerve Activity Monitor And Renal Chemical Denervation In A Canine Model

PART Ⅰ DESIGNING AND ASSEMBLING A MULTIFUNCTIONAL CATHETER SYSTEMObjective:To design and assemble a multifunctional catheter system which endued with functions were needed for the follow-up studies, and test the catheter basically physical characteristics.Methods:Based on the 64 element mini-ultrasonic imaging probe that was previously developed by our study group and Shantou Institute of Ultrasonic Instruments Co., Ltd, nitinol syringe tube that was commercially available from APT Medical Inc. and a platinum wires that was customized by Chongqing Chuanyi No.1 factory. The nitinol syringe tube and the platinum wire were both plated with parylene, and they were assembled to be a concentric micro-needle electrode. The mini-ultrasonic imaging probe and the 8 F catheter were arranged to be an ultrasound catheter. The concentric micro-needle electrode and ultrasound catheter were fixed to be a multifunctional catheter.Results:We succeeded to assemble the nitinol syringe tube and the platinum wire to be a concentric micro-needle electrode, arrange the mini-ultrasonic imaging probe and the 8 F catheter to be an ultrasound catheter and fix the concentric electrode and ultrasound catheter to be a multifunctional catheter. The nitinol syringe tube and the platinum wire were insulated each other, and there was a slim conduit between them allowing liquid pass through; The electrode could be retractable freely and coaxially from the catheter, and has an angle of 40°-60° from the ultrasonic probe, and its dynamic locations could be imaged by the probe.Conclusion:We succeeded to construct a multifunctional catheter system, by which we established a framework of our experimental platform that was needed for the follow-up studies.PART Ⅱ USING MULTIFUNCTIONAL CATHETER SYSTEM TO DETECT RENAL NERVES AND RECORD BIOLOGICAL DISCHARGES IN CANINE MODELS UNDER DIRECT VISIONObjective:To test the multi-function catheter system in imaging renal nerves, recording electromyography (EMG) and celiac sympathetic nerve activity (CSNA) and to make sure the effect of ethanol on renal nerve activity (RNA) under direct vison.Methods:Two wolf-dogs of weight over 30 kg were anesthetized by intraperitoneal injection of 3% pentobarbital (30 mg/kg) and followed by depilation and sanitization. The concentric micro-needle electrode and a bipolar needle electrode were inserted nearby into a quadriceps, a bipolar stimulus electrode were inserted proximal to the two electrodes; Then, under opening surgery, the concentric micro-needle electrode and a bipolar golden hooked-electrode were placed nearby on the same celiac sympathetic nerve. After that, separated one of renal nerves, using the bipolar golden hooked-electrode to hook the renal nerve to record discharges and drip ethanol onto the renal nerve; At last the canines were euthanatized and the bilateral renal arteries together with the kidneys were removed, the multifunctional catheter were placed directly into the renal artery to image the renal nerves.Results:The mini-ultrasonic probe could detect the renal nerves. The EMG and CSNA recorded by the concentric micro-needle electrode were similar or the same to that were recorded by the bipolar needle electrode and bipolar golden hooked electrode in waveform. After dripping ethanol, renal nerve activity disappeared very soon.Conclusion:In this study, we succeed to record EMG and CSNA and imaged renal nerves via the multifunctional catheter system. Moreover, we got the information of ethanol destroyed renal nerve activity very soon. Though all these were under direct vison, yet we got the first-hand of data. We have established an experimental platform for later studies.PART Ⅲ PERCUTANEOUS MULTIFUNCTIONAL CATHE-TER SYSTEM TO ASSESS RENAL NERVE ACTIVITY DIRECTLY AND ABLATE RENAL NERVES IN A CANINE MODELObjective:Renal denervation (RDN) is a promise treatment for diseases with sympathetic over-activity but to be criticized of lacking of achieved target. The objective of this part of study was to probe a direct assessment method of renal sympathetic nerve activity (RSNA) for evaluating RDN effects guided by the multifunctional catheter system.Methods:A total of 18 hypertensive wolf-dogs were divided randomly into an ablation group (n=12) and a sham group (n=6). All canines received renoarteriography first. Then the multifunctional catheter system was delivered into the renal artery with the guidance of X-ray, and the concentric micro-needle electrode was manipulated to record RNA and inject ethanol (in the sham group) or normal saline (in the control group) under the echography of probe. Parameters of immediately changes on RNA and follow-up of blood pressure (BP), blood urea nitrogen (BUN), serum creatinine (sCr) and pathology were evaluated.Results:Two canines were excluded because of accessory renal artery. One canine died after the ablation process. In both groups, images of renal nerves and RNA were obtained. In the ablation group, the recorded RNA disappeared after injection of ethanol, but that changes was only 17 percent in the sham group (P<0.001). Compared with the sham group, BP was decreased in ablation group (all P<0.01), but BUN, sCr were not changed (both P>0.05). Gross examination show 40% percent of cases in both group had hematomas around the renal capsule, histological examination showed target nerve fibers were damaged in the ablation group.Conclusions:Such a mini-invasive, percutaneous and catheter-based evaluation technique have provided a visualized way to directly record RNA and monitor achieved masks of the RDN with real-time. Yet there were 40% percent of cases in both group had complications of hematomas.