[Interventional renal sympathetic denervation - a new approach for patients with resistant hypertension].

The pathophysiology of resistant hypertension is complex. Activation of the sympathetic nervous system has been suggested to be one of the main contributors for maintenance of blood pressure elevation and the development of comorbidities. Catheter-based renal denervation - by ablation of the efferent and afferent renal sympathetic nerves - is a new approach to selectively denervate the kidneys from their sympathetic control. Renal denervation is associated with substantial and sustained blood pressure reduction (24 months), lowers central sympathetic outflow, and reduces whole-body norepinephrine spillover. The procedure is feasible and safe. The randomised controlled Symplicity-HTN-2 trial (results reported at AHA 2010, Nov 13-17) provides important information to determine the role of this new method for the treatment of drug resistant hypertension.

Mahfoud F ，Böhm M 《-》

Reinnervation of renal afferent and efferent nerves at 5.5 and 11 months after catheter-based radiofrequency renal denervation in sheep.

Previous studies indicate that catheter-based renal denervation reduces blood pressure and renal norepinephrine spillover in human resistant hypertension. The effects of this procedure on afferent sensory and efferent sympathetic renal nerves, and the subsequent degree of reinnervation, have not been investigated. We therefore examined the level of functional and anatomic reinnervation at 5.5 and 11 months after renal denervation using the Symplicity Flex catheter. In normotensive anesthetized sheep (n=6), electric stimulation of intact renal nerves increased arterial pressure from 99±3 to 107±3 mm Hg (afferent response) and reduced renal blood flow from 198±16 to 85±20 mL/min (efferent response). In a further group (n=6), immediately after denervation, renal sympathetic nerve activity was absent and the responses to electric stimulation were abolished. At 11 months after denervation (n=5), renal sympathetic nerve activity and the responses to electric stimulation were at normal levels. Immunohistochemical staining for renal efferent (tyrosine hydroxylase) and renal afferent nerves (calcitonin gene-related peptide), as well as renal norepinephrine levels, was normal 11 months after denervation. Findings at 5.5 months after denervation were similar (n=5). In summary, catheter-based renal denervation effectively ablated the renal afferent and efferent nerves in normotensive sheep. By 11 months after denervation the functional afferent and efferent responses to electric stimulation were normal. Reinnervation at 11 months after denervation was supported by normal anatomic distribution of afferent and efferent renal nerves. In view of this evidence, the mechanisms underlying the prolonged hypotensive effect of catheter-based renal denervation in human resistant hypertension need to be reassessed.

Booth LC ，Nishi EE ，Yao ST ，Ramchandra R ，Lambert GW ，Schlaich MP ，May CN ... -  《-》

[Renal artery denervation for treating refractory hypertension].

Arterial hypertension is a major healthcare issue affecting between 30 and 40% of the adult population in industrialized countries. Despite the availability of numerous pharmaceutical treatments, arterial hypertension often remains uncontrolled. A non-negligible percentage of patients are refractory to multiple-drug therapy, which exposes them to an increased risk of cardiovascular events. Percutaneous, renal denervation using a catheter connected to a low energy radiofrequency generator has proven effective in decreasing arterial pressure in patients resistant to medical therapy, by reducing afferent nerve activity. In order to be eligible for this therapeutic approach, patients must have uncontrolled essential hypertension despite treatment with a combination of three anti-hypertensive drugs including a diuretic agent, and ≥ 45mL/min glomerular filtration rate. The initial registry study demonstrated that catheter-based sympathetic renal denervation was a simple and safe procedure resulting in a significant and durable reduction in arterial pressure. Subsequently, a randomized controlled trial (the Symplicity HTN-2 trial) showed a mean 32/12 mmHg decrease in blood pressure measurements in the group of patients who underwent renal denervation whereas no difference was observed in the control group. The reduction in blood pressure was still present at 24-month follow-up. No procedure-related complications were reported and no instances of renal artery stenosis or aneurysmal dilatation were evidenced during the follow-up period. No cases of renal function impairment or deterioration were recorded. This technique seems to be a promising strategy in patients suffering from this serious condition. In order to demonstrate the actual benefit of this technique, we report the case of two patients who underwent renal denervation in our institution.

Benamer H ，Louvard Y ，Garot P ，Unterseeh T ，Hovasse T ，Lefèvre T ，Chevalier B ，Morice MC ... -  《-》

[Expert consensus statement on interventional renal sympathetic denervation for hypertension treatment].

This commentary summarizes the expert consensus and recommendations of the working group 'Herz und Niere' of the German Society of Cardiology (DGK), the German Society of Nephrology (DGfN) and the German Hypertension League (DHL) on renal denervation for antihypertensive treatment. Renal denervation is a new, interventional approach to selectively denervate renal afferent and efferent sympathetic fibers. Renal denervation has been demonstrated to reduce office systolic and diastolic blood pressure in patients with resistant hypertension, defined as systolic office blood pressure ≥ 160 mm Hg and ≥ 150 mm Hg in patients with diabetes type 2, which should currently be used as blood pressure thresholds for undergoing the procedure. Exclusion of secondary hypertension causes and optimized antihypertensive drug treatment is mandatory in every patient with resistant hypertension. In order to exclude pseudoresistance, 24-hour blood pressure measurements should be performed. Preserved renal function was an inclusion criterion in the Symplicity studies, therefore, renal denervation should be only considered in patients with a glomerular filtration rate > 45 ml/min. Adequate centre qualification in both, treatment of hypertension and interventional expertise are essential to ensure correct patient selection and procedural safety. Long-term follow-up after renal denervation and participation in the German Renal Denervation (GREAT) Registry are recommended to assess safety and efficacy after renal denervation over time.

Mahfoud F ，Vonend O ，Bruck H ，Clasen W ，Eckert S ，Frye B ，Haller H ，Hausberg M ，Hoppe UC ，Hoyer J ，Hahn K ，Keller T ，Krämer BK ，Kreutz R ，Potthoff SA ，Reinecke H ，Schmieder R ，Schwenger V ，Kintscher U ，Böhm M ，Rump LC ，Arbeitsgemeinschaft Herz und Niere der Deutschen Gesellschaftfür Kardiologie – Herz- und Kreislaufforschunge V und der Deutschen Gesellschaft für Nephrologiee  V sowie der Deutschen Hochdruckliga e V DHL® – DeutscheGesellschaft für Hypertonie und Prävention ... -  《-》

Catheter-based renal denervation for treatment of resistant hypertension.

Vase H ，Mathiassen ON ，Kaltoft A ，Pedersen EB ，Christensen KL ，Buus NH ，Lederballe O ，Lassen JF ，Bøtker HE ，Thuesen L ... -  《Danish Medical Journal》