What is RDN?
Renal artery denervation is a new minimally invasive radiological procedure for the treatment of hypertension (high blood pressure) which is resistant to combination drug therapy.
How does renal artery denervation work?
This procedure is performed under local anaesthetic by inserting a catheter into an artery in the groin through a small incision and feeding the catheter into the renal arteries which supply blood and nervous stimulation to the kidneys. X-rays are used to allow visualisation of the catheter within the blood vessels and aid in positioning it correctly.
An electric current is then passed through the catheter which heats the wall of the artery and leads to destruction of the nerves within and outside the wall. This in turn results in reduced stimulation to physiological mechanisms in the kidneys which are felt to be responsible for causing hypertension.
It also reduces nerve signals from the kidneys to the brain which are also involved in development of high blood pressure. The catheter is then removed from the groin and any bleeding prevented by firm pressure to the area for several minutes. The procedure takes approximately 40 minutes to perform.
What are the benefits of RDN?
Hypertension (high blood pressure) occurs in approximately 30-40% of the population in the developed world. In patients whose blood pressure is not controlled adequately by drugs there is an increased risk of stroke (CVA), coronary heart disease (and therefore heart attack) and kidney disease which can ultimately lead to kidney failure requiring dialysis. 20% of men and 25% of women have persistently elevated blood pressure despite changing their lifestyle and taking combinations of drug therapy.
It has been shown that reducing blood pressure by 10mm Hg can have a beneficial effect on health problems related to high blood pressure.
The RDN procedure reduces blood pressure in patients who do not respond to more traditional forms of treatment. In one study, blood pressure measurements were significantly reduced 6 months after treatment compared to a group who did not undergo the procedure and improved blood pressure has been seen up to 2 years afterwards. Some patients have also managed to reduce the number of medications they are taking.
How safe is renal artery denervation?
Similar procedures involving placing catheters in the renal arteries have been performed safely by experienced Interventional Radiologists for many years. To date the procedure has been shown to be very safe with no serious complications reported in the medical literature.
Some minor complications have been encountered such as bruising in the groin following puncture of the artery at this site. Patients are observed overnight before being allowed home and then followed up at regular intervals with blood tests, blood pressure measurements and X-ray or ultrasound scans of the kidneys.
No significant effects on kidney function have been demonstrated nor has any arterial abnormality been seen with long term follow up.
Author: Dr Peter Riley, Consultant Diagnostic and Interventional Radiologist practicing at BMI The Priory Hospital.