Introduction on Catheter-based Renal Sympathetic Denervation - Long-term Symplicity™ Renal Denervation Clinical Evidence, New Data and Future Perspectives

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Introduction on Catheter-based Renal Sympathetic Denervation - Long-term Symplicity™ Renal Denervation Clinical Evidence, New Data and Future Perspectives

Hypertension is one of the most important public health problems of the 21st century, with a global prevalence of around 30 %.¹ In 2010, it accounted for 7.5 million deaths worldwide, representing 12.8 % of the global total.² Furthermore, its prevalence is projected to rise to 1.5 billion hypertensive patients in 2025.³ Despite the availability of numerous safe and effective antihypertensive medications, the proportion of hypertensive patients achieving recommended blood pressure (BP) targets is only around 50 %.⁴ Resistant hypertension is generally dened as BP that remains high (>140/90 millimetres of mercury [mmHg]) despite the concomitant use of antihypertensive drugs from more than three drug classes, including a diuretic.⁵ Estimates of its prevalence vary widely, but data from observational studies and clinical trials suggest that 8-30% of treated hypertension patients have resistant hypertension.⁶ Given that cardiovascular mortality doubles with each 20/10 mmHg increase in BP,⁷ resistant hypertension represents a serious global health challenge.

New approaches to the treatment of patients with resistant hypertension are an important clinical need. Percutaneous catheterbased transluminal renal ablation (renal denervation [RDN]) is emerging as a novel treatment approach for resistant hypertension. Renal nerve activation contributes to the pathogenesis of hypertension as a result of renal vasoconstriction; renal blood ow and glomerular ltration rate (GFR) decrease; increased sodium reabsorption and renin release.^8,9 RDN, involving a multiple application of radiofrequency (RF) energy using a catheter, has been shown to provide an effective and safe means of reducing sympathetic outow to and from the kidneys without adversely affecting other functions of the kidney.¹⁰ It is a minimally invasive procedure, characterised by short recovery times and the absence of signicant systemic side effects.¹¹ The treatment has resulted in signicant and sustained BP reductions over 36 months in the majority of patients with resistant hypertension^12-14 and has been associated with improvements in health-related quality of life.¹⁵ A recent study also suggested that RDN is a cost-effective strategy for resistant hypertension.¹⁶

Several devices have been approved for RDN, the most established of which is the Symplicity™ renal denervation system (Medtronic, Inc). The Symplicity Flex™ catheter is specically designed for the renal anatomy, being non-occlusive and 6 French guiding catheter compatible. The Symplicity G2™ generator utilises specic algorithms that ensure optimal delivery of RF energy to the renal artery. The procedure requires application of RF energy to 4-6 locations within each of the renal arteries to effect renal nerve interruption. The technique is straightforward to perform - treatment of renal arteries without angiographic stenosis with the Symplicity Flex catheter requires two minutes duration per treatment for a total bilateral denervation time of 8-12 minutes. Its use is supported by extensive worldwide experience, including a clinical evaluation programme. This review will present the clinical evidence in support of RDN, as well as considering future perspectives on the technique.