Hypertension is a major risk factor for cardiovascular and chronic kidney diseases. Hypertension can be primary or secondary. Primary hypertension does not have a single known cause, but secondary hypertension develops because of an underlying medical condition. Hypertension is traditionally considered resistant if it is not controlled after treatment with 3 or more antihypertensive medicines from different classes.
NICE's guideline on hypertension in adults describes diagnosing and managing hypertension, including resistant hypertension. Current treatments for hypertension include lifestyle modifications and antihypertensive medicines. Blood pressure and treatment are regularly monitored and treatment is adjusted as needed. For resistant hypertension, treatment options include additional medicines and device-based antihypertensive therapies (such as radiofrequency or ultrasound renal denervation, and carotid baroreceptor stimulation).
Before the procedure, renal artery imaging is done to evaluate renal arterial anatomy.
The procedure is usually done under local anaesthesia, with sedation and anticoagulation. A catheter is introduced through the femoral artery and advanced into each renal artery under fluoroscopic guidance. The catheter has 3 guide tubes, each containing a microneedle. Once the catheter is positioned within the target site, the 3 tubes are simultaneously deployed against the intimal surface of the renal artery. The 3 microneedles are advanced through the renal artery wall into the adventitia and surrounding perivascular space. Microdoses of neurolytic agent (medical grade dehydrated alcohol) are then infused slowly into the perivascular space from the distal to proximal end of each renal artery. This ablates the renal nerves leading to the kidney, with the aim of disrupting neurogenic reflexes involved in blood pressure control.
After the catheter is withdrawn, renal artery imaging can be done to identify any adverse vascular events related to the device or the procedure.