The effect of renal denervation on kidney oxygenation as determined by BOLD MRI in patients with hypertension.

OBJECTIVES: Renal denervation (RDN) is a promising therapy for resistant hypertension. RDN is assumed to decrease sympathetic activity. Consequently, RDN can potentially increase renal oxygenation. Blood oxygen level-dependent MRI (BOLD-MRI) provides a non-invasive tool to determine renal oxygenation in humans. The aim of the current study was to investigate the effect of RDN on renal oxygenation as determined by BOLD-MRI. METHODS: Patients with resistant hypertension or the inability to follow a stable drug regimen due to unacceptable side effects were included. BOLD-MRI was performed before and 12 months after RDN. Twenty-seven patients were imaged on 3 T and 19 on 1.5 T clinical MRI systems. RESULTS: Fifty-four patients were included, 46 patients (23 men, mean age 57 years) completed the study. Mean 24-h BP changed from 163(±20)/98(±14) mmHg to 154(±22)/92(±13) mmHg (p = 0.001 and p < 0.001). eGFR did not change after RDN [77(±18) vs. 79(±20) mL/min/1.73 m(2); p = 0.13]. RDN did not affect renal oxygenation [1.5 T: cortical R2*: 12.5(±0.9) vs. 12.5(±0.9), p = 0.94; medullary R2*: 19.6(±1.7) vs. 19.3(1.4), p = 0.40; 3 T: cortical R2*: 18.1(±0.8) vs. 17.8(±1.2), p = 0.47; medullary R2*: 27.4(±1.9) vs. 26.7(±1.8), p = 0.19]. CONCLUSION: The current study shows that RDN does not lead to changes in renal oxygenation 1 year after RDN as determined by BOLD-MRI. KEY POINTS: • Renal denervation significantly decreased ambulatory blood pressure. • Renal denervation did not change renal oxygenation as determined by BOLD-MRI. • Absence of a change in renal oxygenation might be explained by autoregulation.

Renal denervation for the treatment of hypertension: the Dutch consensus.

Since 2010, renal denervation (RDN) is being performed in the Netherlands. To make sure RDN is implemented with care and caution in the Netherlands, a multidisciplinary Working Group has been set up by the Dutch Society of Cardiology (NVVC). The main aim of this Working Group was to establish a consensus document that can be used as a guide for implementation of RDN in the Netherlands. This consensus document was prepared in consultation with the Dutch Association of Internal Medicine (NIV) and the Dutch Society of Radiology (NVVR).

The effect of percutaneous renal denervation on muscle sympathetic nerve activity in hypertensive patients.

OBJECTIVE: The rationale of percutaneous renal denervation (RDN) is based on extensive studies suggesting that renal nerves contribute to hypertension and that they comprise a sensible treatment target. Muscle sympathetic nerve activity (MSNA) is considered to be one of the few reliable methods to quantify central sympathetic activity. The aim of this current study is to determine the effect of RDN on MSNA in a standardized fashion. METHODS: MSNA was determined in 13 patients before and 6months after RDN. Anti-hypertensive medication was stopped before MSNA. If cessation of medication was considered unsafe, a patient was instructed to use the exact same medication on both occasions. RESULTS: Ten sets of MSNA recordings were of good quality for analysis. Mean age was 57 ± 3 years and mean eGFR was 85 ± 18 mL/min/1.73 m(2). MSNA was determined twice during a medication free interval in 5 patients; 1 patient used the exact same medication twice, and 4 patients used different drugs. Mean BP changed from 206 ± 7 over 116 ± 4 mmHg, to 186 ± 6 over 106 ± 3 mmHg, 6 months after RDN (p=0.06 for systolic BP, p=0.04 for diastolic BP). Mean resting heart rate did not change (p=0.44). MSNA did not change after RDN: 37 ± 4 bursts/min and 43 ± 4 bursts/min (p=0.11) at baseline and after RDN, respectively. In the 6 patients with standardized medication use during the MSNA sessions, results were comparable. CONCLUSIONS: Treatment with RDN did not result in a change in MSNA. Changes in BP did not correlate with changes in MSNA.

Renal denervation: a new treatment option in resistant arterial hypertension.

Hypertension is one of the most prevalent cardiovascular risk factors. Despite this high prevalence and a broad availability of effective pharmaceutical agents, a significant proportion of patients do not reach treatment goals. Partly this can be explained by secondary causes of hypertension or non-compliance of patients. Nevertheless, a subgroup of patients can be diagnosed with 'resistant hypertension'. Activation of the sympathetic nervous system is known to be an important factor in the development and progression of systemic hypertension. In this context, a percutaneous, catheter-based approach has been developed using radiofrequency energy to disrupt renal sympathetic nerves. The first studies have shown this technique to be safe, illustrated by a lack of vascular or renal injury. More importantly, catheter-based renal nerve ablation resulted in a significant reduction in blood pressure on top of traditional medical therapy. Additional to the encouraging effects shown on hypertension, a positive influence of this intervention in other conditions, characterised by sympathetic overactivation, may be expected. Though this technique seems promising, further studies are needed to address long-term safety and efficacy of renal denervation in hypertension and other disease states.

Percutaneous renal denervation for the treatment of resistant essential hypertension; the first Dutch experience.

BACKGROUND: In a subpopulation of patients with essential hypertension, therapeutic targets are not met, despite the use of multiple types of medication. In this paper we describe our first experience with a novel percutaneous treatment modality using renal artery radiofrequency (RF) ablation. METHODS: Patients who were resistant to at least three types of antihypertensive medical therapy (office systolic blood pressure ≥ 160 mmHg; n = 9) or who did not tolerate medication (n = 2) were selected. Between July and November 2010, a total of 11 patients received percutaneous RF treatment. Patients were followed up for 1 month after treatment. Urine and blood samples were taken to evaluate the effects on renal function and neurohumeral factors. RESULTS: No periprocedural complications or adverse events during follow-up were noted. A reduction of mean office blood pressure was seen from 203/109 ± 32/19 mmHg at baseline to 178/97 ± 28/21 mmHg at 1 month follow-up (mean difference 25 ± 12 mmHg, p < 0.01). Also, we noted a significant decrease in aldosterone level (391 ± 210 pmol/L versus 250 ± 142 pmol/L; p = 0.03), while there was no decrease in plasma renin activity (190 ± 134 fmol/L/s versus 195 ± 163 fmol/L/s; p = 0.43). No change in renal function was noted. CONCLUSION: Catheter-based renal denervation seems an attractive novel minimally invasive treatment option in patients with resistant hypertension, with a low risk of serious adverse events.