In the issue of the Korean Circulation Journal, Kim et al.6) reports that RDN might reduce the incidence of premature ventricular complex (PVC), prolongation of the QT interval, and VA during acute phase in the porcine AMI model. Even though authors describe the efficacy of RDN using radiofrequency through increased serum norepinephrine level and histology (hematoxylin and eosin staining) around renal artery, tyrosine hydroxylase staining for cholinergic nerve is needed for achieving the successful RDN. Authors demonstrated that successful RDN is achieved by catheter-based RDN using radiofrequency ablation. However, unsolved issues are still remained in the technical and procedural aspects. In terms of technical points, the renal nerve anatomy has played an important role in the development of the RDN technique. The most RDN studies poorly described the site of energy delivery. The efficacy of RDN could be dependent on the nerve abundance near the ablation sites and the renal nerve anatomy in each individual.7) Steigerwald et al.8) demonstrated that the renal nerve are homogenously distributed throughout the renal artery and renal artery nerves are mostly found in the proximal segment of the renal artery and decreased gradually distally in the animal studies. In the part of procedural point, complete RDN with radiofrequency may be difficult to cause irreversible nerve damage due to inconsistent circumferential denervation and inadequate depth for energy delivery.9) Recently, some physicians tried to overcome these limitations. They investigated other catheter-based approaches such as ultrasound, cryogenic balloon or chemical RDN. The peri-adventitial injection of ethanol has been studied to perform a chemical RDN. In addition, electrical high frequency renal nerve stimulation (RNS) has been developed for a more physiological and electrophysiological approach to RDN. The RNS is used to map the sympathetic nerve tissue around renal artery by causing an electrical stimulation-induced blood pressure response to localize sympathetic nerves as ablation target sites.

Although catheter-based RDN have limitations such as less uniform ablation technique and no definite procedural end-point, modulation of the renal nerve activity by RDN could be a reasonable therapeutic option in cardiovascular disease caused by increased sympathetic activity such as drug-resistant hypertension, atrial or VAs and heart failure.