Renal Denervation by Radiofrequency

Background and indications

Renal denervation by radiofrequency (or ultrasound) is an endovascular treatment for resistant hypertension. The renal sympathetic nervous system plays a key role in blood pressure regulation. Denervation applies thermal energy (radiofrequency or ultrasound) to the renal artery walls to disrupt afferent and efferent sympathetic nerve fibers coursing through the arterial adventitia.

It is indicated for patients with confirmed resistant hypertension (blood pressure > 140/90 mmHg on ≥ 3 antihypertensives at optimal doses including a diuretic), after excluding curable secondary hypertension and medication non-adherence.

Pre-procedure assessment

Assessment includes resistant hypertension confirmation by ABPM (24-hour ambulatory blood pressure monitoring), exclusion of curable secondary causes (renal artery stenosis, pheochromocytoma, primary aldosteronism), renal CT angiography (favorable anatomy: diameter > 4 mm, length > 20 mm, no significant stenosis), and renal function panel (GFR > 45 mL/min).

Procedure

Under local anesthesia and sedation, a denervation catheter is introduced through the femoral artery and positioned in the renal artery under fluoroscopic guidance. Radiofrequency (or ultrasound) applications are performed in a helical pattern on the arterial wall of both renal arteries (4-6 applications per artery, each lasting 60-120 seconds). The procedure takes approximately 45 to 60 minutes.

Results and scientific evidence

The double-blind randomized SPYRAL HTN-ON MED trial of 80 patients demonstrated significant ambulatory blood pressure reduction of -7.4/-4.1 mmHg (systolic/diastolic) at 6 months after renal denervation compared to sham (Kandzari et al., The Lancet, 2018; DOI: 10.1016/S0140-6736(18)30951-6). The RADIANCE-HTN SOLO trial confirmed these results with ultrasound technique.

Blood pressure reduction is sustained long-term (follow-up up to 3 years) with reduction in required antihypertensives in some cases.

Risks and complications

Femoral puncture hematoma (< 3%), transient lumbar pain during applications (common, managed with analgesia), renal artery dissection or spasm (< 1%, generally inconsequential). No significant renal function deterioration reported in clinical trials.

Recovery

4-6 hour monitoring. Return to activities the following day. Antihypertensive treatment is maintained and progressively adjusted based on ABPM results at 3 and 6 months.

Practical information

The procedure is performed as an outpatient or short inpatient stay depending on the case. It is performed by an interventional radiologist or interventional cardiologist, in coordination with the treating cardiologist/nephrologist.