Renal Denervation (RDN) is a minimally invasive medical procedure designed to treat high blood pressure, particularly in cases where hypertension remains uncontrolled despite medication. The process involves threading a catheter, typically from an access point in the groin or wrist, up to the renal arteries that supply blood to the kidneys. Once positioned, the device delivers ablative energy to selectively disrupt the overactive sympathetic nerves surrounding the arteries. This nerve disruption aims to reduce nerve signaling between the kidneys and the brain, which in turn helps to lower blood pressure. Like all interventional medical treatments, RDN carries inherent risks and potential adverse events that patients should understand before undergoing the procedure.
Common Issues at the Access Site
The most common issues following renal denervation are related to the site where the catheter is inserted, usually the femoral artery in the groin. These events are generally mild and temporary. Minor bleeding, pain, and bruising around the puncture site occur most frequently, with minor access site complications reported in roughly 5% of patients in clinical trials.
A small collection of blood under the skin, known as a hematoma, can form at the groin, or less commonly, a pseudoaneurysm may develop as a result of a leak in the artery wall. Most access site complications resolve on their own, or require only minor intervention, and do not typically lead to long-term health issues.
Risks to the Renal Artery
More serious, though infrequent, complications involve the renal artery itself, where the ablative energy is delivered. One immediate risk is renal artery dissection, which is a tear in the inner lining of the vessel wall that can occur either during the catheter’s movement or as a result of the energy application.
The application of energy may also cause a temporary artery spasm, where the vessel constricts, or lead to the formation of a blood clot within the artery. A clot poses a risk of embolization, where it breaks off and travels downstream, potentially blocking smaller vessels. The development of renal artery stenosis, which is a narrowing of the artery, can occur months after the procedure due to inflammation or scarring from the ablative energy. While the incidence of new vascular changes, like stenosis or dissection, is low—reported to be around 3.1% of patients in some systematic assessments—they may require immediate medical intervention, such as the placement of a stent.
Monitoring Long Term Kidney Function
Concerns about the long-term systemic impact on the kidney, especially its filtering capacity, necessitate careful monitoring after renal denervation. A temporary decline in kidney function, known as acute kidney injury (AKI), can sometimes occur in the immediate aftermath of the procedure. This is often related to the use of iodinated contrast dye needed to visualize the arteries during the catheter placement, or temporary blood flow changes following the nerve ablation.
The primary long-term safety indicator for the kidneys is the estimated glomerular filtration rate (eGFR), a measure of how well the kidneys filter waste from the blood. Follow-up studies generally show that RDN does not lead to a sustained negative impact on GFR. Over several years, the rate of eGFR decline observed in patients who have undergone RDN is consistent with the natural, age-associated decline expected in the general population.
Even in patients with pre-existing chronic kidney disease, the procedure has been shown to maintain its safety profile over several years of follow-up. Therefore, sustained post-procedure monitoring of both blood pressure and kidney function is an ongoing requirement to ensure continued safety and therapeutic benefit.