Renal denervation

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The renal denervation ( latin ren = kidney) is an interventional radiological method for the treatment of hypertension . The nerve pathways between the brain and the kidney are interrupted in a minimally invasive manner .

indication

The kidney is central to regulating blood pressure. When there is an increased efferent (from the brain to the kidney) activity of the sympathetic nervous system (a certain part of the autonomic nervous system) and the resulting increased kidney activity, the blood pressure-increasing substances renin and noradrenaline are released. For the treatment of patients with renal and sometimes essential hypertension (high blood pressure), the efferent and afferent (leading from the kidney to the brain) renal nerves offer a treatment approach.

method

Schematic representation of renal denervation

With renal denervation , all efferent and afferent nerve pathways between the kidney and brain are electrically obliterated and thus interrupted. For this purpose, a catheter (thin tube with the sclerosing instrument at the end) is inserted into the renal artery , with which the nerve tracts are sclerosed precisely. Single-point and multi-point catheters are used. With single-point catheters, one sclerotherapy point - also called an ablation point - is set by the surgeon after the other. It is recommended to arrange 4-6 dots in a spiral pattern. However, the planned distribution of the points often differs from the actual one, which is why some surgeons prefer the use of multi-point catheters. In the case of multi-point catheters, the distribution of the points on the catheter is specified via attachments and is accordingly easier to control. In animal experiments it has been shown that the number and distribution of the points have a significant influence on the success of the treatment and the safety of the patient. The ablation points should be 5 mm away to prevent the risk of renal artery stenosis .

All available systems work with high temperatures to guarantee the separation of the nerve tracts. In most systems, the endothelium (the innermost layer on the walls of the blood vessels) is also damaged. The challenge is to bring in enough heat to separate the nerves, but at the same time to keep the temperatures as low as possible to counteract endothelial damage. One system available on the market uses a balloon attached to the catheter to cool the inner arterial wall. This is to prevent endothelial damage.

effectiveness

The effectiveness of renal denervation has so far only been investigated in a few long-term studies with only small numbers of patients, since renal nerve obliteration is a relatively new treatment method. The first report was published by M. Schlaich in 2009, which was followed by open, non-placebo-controlled studies, some of which had outstanding results, one of which showed an average reduction in blood pressure of 32/14 mmHg (SYMPLICITY HTN-2). Despite the insufficiently established proof of effectiveness, this method is already used in more than eighty countries outside of clinical studies, sometimes with euphoric expectations.

In contrast, the first prospective multicenter randomized clinical study (the so-called SYMPLICITY HTN-3 study ) with a sham intervention as a placebo intervention including 535 American patients with resistant high blood pressure despite taking an average of 5.1 different antihypertensive agents, demonstrated the effectiveness and effectiveness of the renal drugs Do not demonstrate denervation. The systolic blood pressure after six months was on average 14.1 mmHg lower than before the procedure, compared to 11.7 mmHg in the control group, which thus resulted in a minimal and insignificant blood pressure reduction of an average of 2.4 mmHg ( confidence interval - 6.9 to 2.1 mmHg). The difference in systolic blood pressure of 15 mmHg in the verum group compared to the placebo group six months after the procedure as a postulated study goal could therefore not be proven, which is why the extensive indication of renal denervation outside of clinical studies must be questioned.

Individual evidence

  1. ↑ a b C.P. Nähle, H. Schild, K. Wilhelm: Renal Denervation. Is it ready for widespread use? In: German Medical Weekly. No. 138, 2013 ISSN  0012-0472 , pp. 2212-2218
  2. ↑ a b c F. Mahfoud, D. Linz • M. Bohm: Heart and kidney. High pressure therapy through renal denervation. In: Herz No. 38, 2013, ISSN  0340-9937 , pp. 746-753
  3. ↑ a b c d A. Saleh: Renal Denervation. Current developments In: Der Radiologe No. 53, 2013 ISSN  0033-832X , pp. 216–222
  4. ↑ a b K. Kara, H. Bruck, P. Kahlert, B. Plicht, AA Mahabadi, T. Konorza, R. Erbel: Renal denervation. Current status and perspectives. In: Herz No. 37, 2012, ISSN  0340-9937 , pp. 746-753.
  5. ↑ Deepak L. Bhatt, David E. Kandzari, William W. O'Neill et al .: A Controlled Trial of Renal Denervation for Resistant Hypertension. In: The New England Journal of Medicine. (N Engl J Med) April 10, 2014, Vol. 370, No. 15, pp. 1393-1401, doi : 10.1056 / NEJMoa1402670 .