Interventional Renal Sympathetic Denervation

Interventional renal sympathetic denervation (synonym: renal denervation (RDN)) is a therapeutic minimally invasive internal medicine procedure that can be used to treat severe refractory (without treatment success) hypertension (high blood pressure). Targeted denervation (severing of the nerve) is performed using a precise selective catheter technique so that both the afferent and efferent renal nerves can be specifically separated by radiofrequency energy. By means of renal sympathetic denervation, a significant (marked) and permanent reduction in blood pressure as well as a reduction in sympathetic activity is possible. The latter leads to the fact that 3 months after the intervention, the heart rate is also significantly lower – on average by 2, 5 beats per minute – than patients with sham treatment.

Indications (areas of application)

Therapy-refractory hypertension-according to recent studies, interventional renal sympathetic denervation is to be used for therapy-refractory hypertension that is not based on primary pathologic changes in metabolism, tumors, or anatomic changes in blood pressure regulation. The international multicenter randomized Symplicity-HTN-2 study on which the indication was based included 106 patients with refractory hypertension who, despite triple antihypertensive therapy (blood pressure-lowering therapy), failed to achieve a guideline-compliant blood pressure reduction (occasional blood pressure < 160 mmHg systolic, in patients with type 2 diabetes mellitus < 150 mmHg). The positive result of the Symplicity-HTN-2 study is challenged by the Symplicity-HTN-3 study (> 500 patients). Another study with a stricter study protocol and careful selection of concomitant antihypertensive therapy had a positive result: at the primary end point, a decrease of 15.8 mmHg was achieved, compared with a decrease of 9.9 mmHg in systolic blood pressure in the control group.See also the study review under “Renal Denervation in Treatment-Resistant Hypertension (S1)”.According to recent studies, renal denervation significantly lowers systolic and diastolic blood pressure compared with sham treatment.

Contraindications

If there is an indication for performing the procedure, potential contraindications should be evaluated on an individual basis. Causes of hypertension that cannot be treated with interventional renal sympathetic denervation are listed above.

Before therapy

Preinterventional exclusion of various causes of hypertension that should be considered contraindications (contraindications) to interventional renal sympathetic denervation:

  • Pheochromocytoma – a pheochromocytoma is a rare tumor of the adrenal medulla that can produce the catecholamines (hormones) epinephrine and norepinephrine, among others, leading to paroxysmal hypertension (seizure-like hypertension) or persistent hypertension (permanent elevation of blood pressure).
  • Primary hyperaldosteronism (Conn syndrome) – is one of the rarer causes of hypertension in its classic (hypokalemic) form, with an incidence of about 1%; however, up to 10% of patients with hypertension have normokalemic (normal potassium) hyperaldosteronism
  • Cushing’s syndrome – disorder in which too much ACTH (adrenocorticotropin, also adrenocorticotropic hormone; ACTH for short) is produced by the pituitary gland (pituitary gland), resulting in increased stimulation of the adrenal cortex and, as a consequence, excessive cortisol production. Cushing’s syndrome may be a possible cause of refractory hypertension.
  • Renovascular and/or renoparenchymatous hypertension – this form of hypertension is renal in origin (kidney as the cause of hypertension) and therefore cannot be treated with denervation. Magnetic resonance imaging is performed to evaluate the renal arteries. Optimal conditions for the intervention are here in each case a single created Arteria renalis sinistra and dextra with a minimum length (departure aorta (aorta) to the first bifurcation / bifurcation) of 20 mm and a diameter greater than 4 mm.
  • Thyroid dysfunction – increased formation and release of thyroid hormones, among other things, leads to an increase in blood pressure and must therefore be excluded before intervention.
  • Obstructive sleep apnea syndrome (OSAS; breathing pauses during sleep caused by airway obstruction, often occurring several hundred times per night) – due to sympathetic activation resulting from catecholamine release, 40-60% of OSAS patients also have elevated blood pressure during the day.
  • Other exclusion criteria include:
    • Myocardial infarction (heart attack), unstable angina pectoris (“chest tightness”; sudden onset of pain in the heart area), insult (cerebral stroke) < 6 months
    • Hemodynamically relevant valve disease.
    • Diabetes mellitus type 1
    • ICD (implantable cardioverter defibrillator) or pacemaker
    • Pregnancy

The procedure

Through a catheter system equipped with an electrode at the tip, a radiofrequency energy is precisely applied in a precise treatment rhythm at a distance of 5 mm to just before the ostium (opening) of the renal artery. The radiofrequency generator required for this purpose has a safety algorithm so that application of an incorrect radiofrequency energy can be prevented. Within less than an hour, the treatment is completed.

After the therapy

Follow-up examinations are necessary to assess the success of treatment and to check whether complications have occurred.

Possible complications

  • Moderate to severe pain
  • Bleeding and hematoma (bruising)
  • Allergic reactions
  • Necrosis (death) of the vessel wall and damage to the cells in the vessel wall.
  • Intimaproliferation (proliferation of the inner wall of the vessel).