In patients with treatment resistant hypertension renal nerve ablation emerged as an effective interventional approach of treating hypertensive disease with a progressively increasing fall in blood pressure. Decreased activity of the sympathetic nervous system is one of the major underlying pathogenetic mechanism of the fall in blood pressure but the precise mechanisms that causes the fall in blood pressure in the short-term and, in particular, long-term remains elusive. The objective of the study is to understand the pathogenetic mechanisms of renal denervation beyond the reduced activity of the sympathetic nervous system. In 100 hypertensive patients most advanced technology will be applied, before and repeatedly after renal denervation, throughout the follow-up period of 1 year. Systemic activity of the renin angiotensin aldosterone system, renal perfusion (by MRI spin labeling technique), local activity of the renin angiotensin system in the kidney (urinary angiotensinogen concentrations), sodium excretion and total sodium content (23 Na-MRI technique) and vascular remodelling of small (retinal arterioles 50 - 150 µm) and large arteries (carotid - femoral pulse wave velocity and augmentation index, both measured over 24 hours) will be assessed. Identification of the pathogenetic mechanisms involved in the fall in blood pressure after renal denervation may help to identify those hypertensive patients that profit most from renal nerve ablation in terms of blood pressure reduction. The investigators propose the following hypotheses why a progressive decrease in blood pressure happens, in addition to the decreased activity of the central nervous system, after renal nerve ablation: Short term effects: A)Preservation of renal function and perfusion B)Reduction of local RAS activity in the kidney C)Exaggerated sodium excretion immediately after renal nerve ablation Long term effects: D)Decrease of total sodium content after 6 and 12 months E)Improvement of vascular wall properties after 6 and 12 months
Study Type
OBSERVATIONAL
Enrollment
41
percutaneous selective renal sympathetic nerve ablation with the use of the Symplicity Catheter system
Clinical Research Unit, Department of Nephrology and Hypertension, University of Erlangen-Nürnberg
Erlangen, Germany
Klinik für Innere Medizin, Kardiologie, Angiologie und Internistische Intensivmedizin, Universitätsklinikum des Saarlandes
Homburg/Saar, Germany
office BP
change in office blood pressure from baseline to 6 months post-renal denervation
Time frame: baseline, 6 months
24-ABPM
change in 24 hour ambulatory blood pressure (ABPM) from baseline to 6 months post-renal denervation
Time frame: baseline, 6 months
Magnetic resonance imaging (MRI)
* change in total sodium content measured by MRI from baseline to 6 months post-renal denervation * change in renal perfusion measured by MRI from baseline to 3 months post-renal denervation
Time frame: baseline, 3 and 6 months
Albuminuria
change in urinary albumin/creatinine ratio from baseline to 6 months post-renal denervation
Time frame: baseline, 6 months
Systemic RAS activity
* change in sodium, potassium and creatinine from baseline to 6 months post-renal denervation * change in aldosterone excretion from baseline to 6 months post-renal denervation * change in sodium/potassium ratio from baseline to 6 months post-renal denervation * change in plasma renin activity and angiotensin II concentration at least 30 minutes of rest in a supine position and immediately after standing from baseline to 6 months post-renal denervation
Time frame: baseline, 6 months
Vascular structure and function of large and small arteries
* change in flow-mediated vasodilation (FMD)from baseline to 6 months post-renal denervation * change in scanning laser Doppler flowmetry (SLDF) from baseline to 6 months post-renal denervation * change in funduscopy from baseline to 6 months post-renal denervation * change in pulse wave analysis (PWA) from baseline to 6 months post-renal denervation * change in pulse wave velocity (PWV) from baseline to 6 months post-renal denervation * change in urinary albumine/creatinine ratio (UACR) of the morning spot urine sample from baseline to 6 months post-renal denervation
Time frame: baseline, 6 months
Local RAS activity
change in urinary angiotensinogen concentration from the morning spot urine from baseline to 6 months post-renal denervation
Time frame: baseline, 6 months
BP
* change in office BP from baseline to 3 and 12 months post-renal denervation * change in 24 hour ABPM from baseline to 3 and 12 months post-renal denervation
Time frame: 3 and 12 months
MRI
* change in total sodium content measured by MRI from baseline to 12 months post-renal denervation * change in renal perfusion measured by MRI spin labelling technique from baseline to 1 day post-renal denervation
Time frame: 1 day and 12 months
Local RAS activity
change urinary angiotensinogen concentration from the morning spot urine from baseline to 1 day, 3 and 12 months post-renal denervation
Time frame: 1 day, 3 and 12 months
Systemic RAS activity
* change in sodium potassium and creatinine from baseline to 1 day, 3 and 12 months post-renal denervation * change in aldosterone excretion from baseline to 1 day, 3 and 12 months post-renal denervation * change in sodium/potassium ratio from baseline to 1 day, 3 and 12 months post-renal denervation * change in plasma renin activity and angiotensin II concentration at least 30 minutes of rest in a supine position and immediately after standing from baseline to 1 day, 3 and 12 months post-renal denervation
Time frame: 1 day, 3 and 12 months
Albuminuria
\- change in albuminuria from baseline to 3 and 12 months post-renal denervation
Time frame: 3 and 12 months
Vascular structure and function of large and small arteries
* change in flow mediated vasodilation (FMD) from baseline to 12 months post-renal denervation * change in scanning laser Doppler flowmetry (SLDF) from baseline to 12 months post-renal denervation * change in funduscopy from baseline to 3 and 12 months post-renal denervation * change in pulse wave analysis (PWA) from baseline to 12 months post-renal denervation * change in pulse wave velocity (PWV) from baseline to 12 months post-renal denervation * change in urinary albumine/creatinine ratio of the morning spot urine sample from baseline to 3 and 12 months post-renal denervation
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Time frame: 3 and 12 months