Renal denervation is a minimally invasive procedure that uses a catheter to disable overactive nerve signals running between the kidneys and the brain, lowering blood pressure. It targets the sympathetic nerves bundled around the renal arteries, the same “fight or flight” nerves that, when chronically overactive, drive the body to retain salt and water and keep blood vessels constricted. The procedure takes about an hour, typically requires an overnight hospital stay, and was approved by the FDA in November 2023 for use alongside medication and lifestyle changes in people with hypertension.
How Kidney Nerves Drive Blood Pressure
The kidneys are not just filters. They’re wired directly into the sympathetic nervous system through two sets of nerve fibers that run along the outer wall of the renal arteries. Outgoing (efferent) nerve fibers tell the kidneys to hold onto sodium and water, reduce blood flow through the kidney, and release renin, an enzyme that triggers a hormonal chain reaction raising blood pressure even further. Incoming (afferent) fibers send signals back to the brain that ramp up sympathetic activity throughout the entire body, increasing heart rate and tightening blood vessels system-wide.
In people with hypertension, this two-way communication loop can become self-reinforcing. The kidneys signal the brain to raise blood pressure, and the brain signals the kidneys to retain more fluid, which raises blood pressure further. Renal denervation disrupts both directions of this loop. By ablating the nerve fibers wrapped around the renal arteries, the procedure reduces not just local kidney-level nerve activity but whole-body sympathetic tone.
What Happens During the Procedure
The procedure is performed in a catheterization lab, similar to the setting used for heart stent placement. A thin catheter is inserted through a blood vessel in the groin and threaded up to the renal arteries under X-ray guidance. Once positioned, the catheter delivers energy to the artery wall, destroying the nerve fibers embedded in the outer layer of the vessel. The average procedure takes about 61 minutes, with roughly 17 minutes of X-ray (fluoroscopy) time.
Two energy types are used in current systems. Radiofrequency denervation applies targeted heat through small electrodes at multiple points along the artery. Ultrasound denervation uses sound waves to create a more circumferential ablation pattern. A meta-analysis of randomized, sham-controlled trials found that ultrasound-based systems produced a greater reduction in 24-hour ambulatory systolic blood pressure compared to radiofrequency systems, with a difference of about 2.4 mmHg between the two approaches. Both methods significantly lowered blood pressure compared to a sham procedure. The FDA-approved Paradise system uses the ultrasound approach.
Who Is a Candidate
Renal denervation was originally studied in people with resistant hypertension, defined as blood pressure that stays at or above 140 mmHg systolic despite taking three or more medications including a diuretic. More recent guidelines from the European Society of Cardiology have broadened the picture slightly: the procedure may also be considered for people with uncontrolled blood pressure on fewer than three medications, particularly if they have elevated cardiovascular risk and a preference for the procedure after discussing risks and benefits with their care team.
Not everyone with high blood pressure qualifies. Several conditions rule people out:
- White-coat hypertension: If blood pressure reads high in the office but normal on a 24-hour ambulatory monitor, denervation is not appropriate.
- Renal artery anatomy: The main renal artery needs to be at least 4 mm in diameter and 20 mm long for the catheter to fit and work safely. Patients with significant atherosclerosis, prior stenting, or multiple small accessory arteries may not be eligible. Imaging with CT or MRI is required beforehand.
- Kidney function: Most centers require a minimum kidney filtration rate, with cutoffs ranging from 30 to 45 mL/min depending on the facility.
- Secondary causes: Conditions like adrenal tumors or hormone-producing disorders that independently cause high blood pressure need to be ruled out first.
- Medication adherence: If blood pressure is “resistant” simply because medications aren’t being taken consistently, that issue is addressed before considering the procedure.
How Much It Lowers Blood Pressure
Renal denervation does not replace medication. In the RADIANCE II trial, published in JAMA, ultrasound renal denervation reduced daytime ambulatory systolic blood pressure at two months compared to a sham procedure, with no major adverse events. The reductions are meaningful but modest. Across trials, the procedure typically lowers systolic blood pressure by roughly 5 to 8 mmHg on a 24-hour ambulatory reading. That may sound small, but population-level data consistently show that even a 5 mmHg sustained drop in systolic pressure reduces the risk of stroke and heart attack substantially.
The 2024 European cardiology guidelines classify renal denervation as a “may be considered” option (class IIb recommendation), meaning it’s supported by evidence but is not yet a first-line or standard treatment. It should be performed at centers with meaningful procedural volume, and the decision requires a shared discussion between the patient and a multidisciplinary team.
Safety and Recovery
The procedure’s safety profile is reassuring based on available data. In a study of 76 patients who underwent imaging of their renal arteries six months after the procedure, no cases of significant renal artery narrowing (70% or greater blockage) were found. Two patients developed mild, nonsignificant narrowing in the 50 to 69% range. Late-onset narrowing remains something to watch for, particularly if blood pressure climbs again or kidney function changes after an initially successful procedure.
Recovery is straightforward. After the catheter is removed, you lie flat for at least an hour and are monitored for several hours. Most patients stay overnight and go home the next day. Some centers have explored same-day discharge after seven or more hours of monitoring, though this is not yet standard practice. The main procedural risks are related to vascular access at the groin insertion site, similar to any catheter-based procedure: bruising, minor bleeding, or rarely, a pseudoaneurysm at the puncture site.
What Renal Denervation Does Not Do
The procedure is not a cure for hypertension. It is explicitly approved for use alongside medications and lifestyle changes, not as a substitute for them. Some patients may be able to reduce the number of blood pressure pills they take over time, but that decision is made based on follow-up readings, not assumed. The blood pressure response also varies between individuals, and there is no reliable way yet to predict beforehand who will respond strongly and who will see a smaller effect.
The nerves targeted by the procedure do not regenerate in a way that fully restores their original function, based on current evidence. However, because the procedure is relatively new in widespread clinical use, long-term data beyond a few years remains limited. Ongoing follow-up from the major trials will clarify whether blood pressure reductions hold steady over five to ten years.