Renal denervation is a minimally invasive, catheter-based procedure designed to treat high blood pressure by targeting the nerves connecting the sympathetic nervous system to the kidneys. Using energy, specialists disrupt the signals these nerves send, offering a different approach for managing hypertension.
The Role of Kidneys in Blood Pressure Regulation
The sympathetic nervous system helps regulate blood pressure through its communication with the kidneys. This system controls functions like heart rate and the constriction of blood vessels. When these nerves are overactive, they can send excessive signals to the kidneys, contributing to an increase in blood pressure. This overactivity prompts the kidneys to retain more salt and water, increasing the volume of blood in circulation.
This signaling also triggers the kidneys to release a hormone called renin. Renin initiates a cascade of hormonal events that ultimately cause blood vessels throughout the body to narrow, a process known as vasoconstriction. This narrowing of the vessels further elevates blood pressure. The combined effect of increased blood volume and constricted arteries creates a state of sustained hypertension.
The Renal Denervation Procedure
The renal denervation (RDN) procedure is performed by a specialist, such as an interventional cardiologist or radiologist. Patients are given a sedative to ensure they remain comfortable throughout the process, which takes about one to two hours. Because it does not require general anesthesia, recovery is often quicker than with more invasive surgical options.
The procedure begins with a small incision in the groin to access the femoral artery. Using imaging for guidance, the physician threads a thin, flexible tube called a catheter through the artery to the renal arteries, which supply blood to the kidneys. The catheter is then positioned within each renal artery to deliver the treatment.
Once in place, the catheter delivers controlled bursts of energy to the outer wall of the artery, where the sympathetic nerves are located. This energy can be in the form of either radiofrequency (heat) or ultrasound waves. The goal is to ablate, or disrupt, these overactive nerves, reducing their ability to send signals that elevate blood pressure.
Patient Candidacy for the Procedure
A careful evaluation by a medical team determines who is a suitable candidate for renal denervation. The procedure is primarily intended for individuals with “resistant hypertension.” This is defined as high blood pressure that remains above target levels despite the patient taking three or more blood pressure medications at their optimal doses, one of which is a diuretic.
Patients need to have a systolic blood pressure reading that is consistently high, for instance, above 140 mmHg, even with their medication regimen. The structural health of the patient’s blood vessels is also considered, as healthy renal arteries are needed for the procedure to be performed safely.
Conversely, certain conditions would exclude a person from being a candidate. Individuals with severely reduced kidney function are not eligible for the procedure. Anatomical issues with the renal arteries, such as stenosis (narrowing) or fibromuscular dysplasia (abnormal cell growth in artery walls), can also make the procedure unsafe. A thorough screening is performed to rule out secondary causes of hypertension before considering RDN.
Post-Procedure Expectations and Monitoring
Following the renal denervation procedure, patients are monitored in the hospital for a short period, sometimes just for a few hours or overnight, to ensure there are no complications at the catheter insertion site. Most individuals can walk within a few hours and return to their normal, non-strenuous activities within a few days. Heavy lifting and vigorous exercise are discouraged for a short time.
The reduction in blood pressure is not immediate. The effects of the nerve disruption occur gradually, with noticeable changes developing over the weeks and months following the procedure. Regular follow-up appointments are scheduled to monitor the patient’s blood pressure and overall health status.
Renal denervation is not considered a cure for hypertension. Patients should expect to continue with their blood pressure management plan, which includes medication. Over time, a doctor may be able to adjust the treatment plan, potentially reducing the number of medications or their dosages. Maintaining a healthy lifestyle through diet and regular physical activity remains a fundamental part of managing blood pressure long-term.