Catheter-Based Renal Sympathetic Denervation for Resistant Hypertension: A Multicentre Safety and Proof-of-Principle Cohort Study

1. Krum H, Schlaich M, Whitbourn R, Sobotka PA, Sadowski J, Bartus K, Kapelak B, Walton A, Sievert H, Thambar S, Abraham WT, Esler M, ,  Catheter-based renal sympathetic denervation for resistant hypertension: a multicentre safety and proof-of-principle cohort study.,  Lancet,  373 (9671) 1275-81. View in PubMed

The authors emphasize that in spite of the many recent pharmacologic developments for antihypertensive therapy, the percentage of patients achieving adequate blood pressure control remains low due to many factors, including physician inertia, patient noncompliance and nonadherence. Thus, new approaches for the management of hypertension, especially resistant hypertension, are needed. The authors contend that renal sympathetic nerves are crucial for the initiation and maintenance of hypertension in many patients and propose that renal sympathetic denervation by radiofrequency ablation using a percutaneous catheter-based approach can provide a safe and effective means of treating resistant hypertension. Forty-five patients with resistant hypertension but without overt renal disease or diabetes were subjected to radiofrequency ablation. Renal angiography was done in some of the patients up to 30 days after the procedure to detect possible complications, which were infrequent and mostly minor. Office blood pressures, measured at 1, 3, 6, 9, and 12 months after the procedure, were reduced significantly at all periods tested with an average of -24/-11 mmHg at 9 months in 20 patients followed for this time period. The authors conclude that catheter-based renal denervation is an effective means to elicit substantial and sustained reductions in arterial pressure in patients with resistant hypertension. However, they recognize that this study only provides proof of principle, and there is a need for a prospective clinical trial. 

Clinical Implication/Application

Although the study was performed in a relatively small number of patients, it does provide data supporting the concept that, at least in some patients, a chronic overactivity of the renal sympathetic nerves may be responsible for long-term effects on the kidney that lead to the development and maintenance of hypertension. The results thus provide further evidence to support the critical role of the kidney in the pathophysiology of hypertension. Enhanced renal nerve activity has been shown to increase renal norepinephrine levels and renin release as well as cause direct effects to reduce renal blood flow and glomerular filtration rate while enhancing fractional sodium reabsorption. Furthermore, the enhanced intrarenal renin levels lead to increased intrarenal formation of angiotensin I and II, which also lead to further enhancement of fractional sodium reabsorption and reduction in renal hemodynamics. Therefore, to the extent that a patient has increased renal sympathetic nerve activity, then ablation of the renal nerves may be useful in treating the hypertension. This proof-of-principle study in a small cohort of patients provides exciting data in support of the utility of this approach. Nevertheless, it would be prudent to consider reserving such a procedure for patients that are clearly resistant to pharmacologic approaches and have evidence for increased activity of the sympathetic nervous system. Because medications received by the patients were not completely under the control of the investigators, there is uncertainty regarding the interactions between the medications and the renal denervation. Thus, it is clear that a carefully controlled trial is needed before the actual efficacy of this procedure can be ascertained. In addition, the technique of percutaneous catheter-based treatment is not without risk, but the authors emphasize that, except for the pain experienced during the radiofrequency treatment, the adverse effects were minor.