Renal denervation (RDN) represents a therapeutic option for individuals whose high blood pressure has not responded adequately to conventional treatments, including lifestyle changes and multiple medications. This minimally invasive procedure targets specific nerves near the kidneys to help lower blood pressure.
Understanding Renal Denervation
Renal denervation is a minimally invasive, catheter-based procedure to treat resistant hypertension. This condition exists when blood pressure remains elevated despite a patient taking at least three different blood pressure medications, including a diuretic, at their maximum tolerated doses.
A catheter is inserted into the femoral artery in the groin and guided to the renal arteries, which supply the kidneys. Once positioned, the catheter delivers energy, typically radiofrequency or ultrasound, to the walls of the renal arteries. This energy disrupts the overactive sympathetic nerves. These nerves contribute to high blood pressure by increasing sympathetic nervous system activity, which can lead to vasoconstriction, increased heart rate, and fluid retention. By reducing this nerve activity, RDN aims to decrease overall blood pressure.
Defining and Measuring Success
The success of renal denervation is quantified by objective measures related to blood pressure control and medication reduction. A primary metric is a significant reduction in blood pressure, assessed through office blood pressure readings and 24-hour ambulatory blood pressure monitoring (ABPM). ABPM provides an average blood pressure reading over a full day and night, offering a more accurate picture of a patient’s typical blood pressure fluctuations.
Another important measure involves reducing or discontinuing antihypertensive medications. For many, the goal is not necessarily to eliminate all medications but to achieve better blood pressure control with fewer drugs or at lower doses. This improves adherence and reduces medication-related side effects. The procedure is successful if it leads to sustained blood pressure reductions that improve cardiovascular health outcomes, even without complete normalization.
Factors Influencing Success
Several elements influence the success of renal denervation, starting with careful patient selection. Patients with severe primary hypertension may experience a more desirable response. Identifying and excluding secondary causes of hypertension, such as fibromuscular dysplasia or renal artery stenosis, is also important before considering RDN.
Procedural technique plays a significant role in achieving effective denervation. The operator’s experience and the completeness of the nerve ablation are factors that can affect outcomes. This includes ensuring sufficient energy applications are delivered to all relevant areas of the renal arteries, including any accessory renal arteries, to maximize nerve disruption. The anatomy of the renal arteries, such as their diameter and length, can also impact the feasibility and effectiveness of the procedure.
Post-procedure patient management is also important for long-term success. Continued adherence to prescribed medications and lifestyle modifications (dietary changes, regular exercise) remains important. Regular follow-up appointments allow healthcare providers to monitor blood pressure changes and adjust medication as needed, helping to sustain the benefits of the procedure.
Current Success Rates and Outcomes
Recent clinical trials and real-world evidence have provided insights into the effectiveness of renal denervation. The SYMPLICITY HTN-3 trial, initially showing no significant difference at six months, demonstrated sustained reductions in both office and 24-hour ambulatory systolic blood pressure (SBP) at three years in patients who underwent RDN compared to a sham procedure. Specifically, the adjusted treatment difference at three years was 22.1 mm Hg for office SBP and 16.5 mm Hg for 24-hour ambulatory SBP, both favoring RDN.
The SPYRAL HTN-OFF MED trial, which evaluated RDN in patients not taking antihypertensive medications, showed a significant reduction in 24-hour SBP of 4.7 mm Hg compared to a 0.6 mm Hg reduction in the sham group, indicating a clear benefit from the procedure. For patients on medications, the SPYRAL HTN-ON MED trial also demonstrated a significant reduction in 24-hour SBP of 9.0 mm Hg in the RDN group versus 1.6 mm Hg in the sham group at six months.
The RADIANCE-HTN SOLO and RADIANCE II trials, utilizing an ultrasound-based system, showed a consistent reduction of 6.3 mm Hg in daytime ambulatory SBP in the RDN group compared to the sham control. These trials also reported a 5.5 mm Hg lower office SBP in the RDN group. Long-term data suggest that blood pressure reductions can be sustained for up to nine years, often accompanied by a reduction in antihypertensive medications.