Renal Denervation: Past, Present, and Future

Hypertension remains a leading cause of cardiovascular morbidity and mortality worldwide. It is estimated that 12.8% of hypertensive adults have resistant hypertension. The sympathetic nervous system is a well-known contributor to the pathophysiology of resistant hypertension. Renal denervation has emerged as an effective procedure to treat resistant hypertension by blocking the sympathetic nervous system. The medical device industry has developed various catheters in an effort to achieve better denervation in the absence of available testing to document adequate denervation. By adding a sham control group to the study design, researchers found that the results of the Renal Denervation in Patients With Uncontrolled Hypertension study (SYMPLICITY HTN-3) showed that renal denervation was not superior to placebo in decreasing systolic blood pressure. Although SYMPLICITY HTN-3 successfully addressed many issues that might have biased the previously published data, incomplete denervation caused by limited operator experience, catheter design, and the radiofrequency ablation technology may have accounted for the discrepancy of the results. This, along with differences in the study design and population, should direct future renal denervation studies. This article reviews the available literature and proposes future directions for renal denervation studies. It also provides a detailed comparison of the available catheters and their respective clinical data.