2 The procedure
2.1.1 Hypertension is a major risk factor for cardiovascular disease and chronic renal disease. First-line treatment usually involves lifestyle changes. Antihypertensive medications (in combinations, as required) are used if hypertension persists. Sympathetic denervation of the renal artery is considered if hypertension fails to respond adequately to these measures. An example of criteria used to select patients for the procedure is given in the Joint UK Societies' Consensus Statement on Renal Denervation for Resistant Hypertension.
2.2.1 Percutaneous transluminal radiofrequency sympathetic denervation of the renal artery for resistant hypertension aims to disrupt neurogenic reflexes involved in blood pressure control.
2.2.2 The procedure is usually carried out using local anaesthesia, conscious sedation and anticoagulation. A catheter is introduced via the femoral artery and advanced into each renal artery under fluoroscopic control. The catheter is connected to a generator which delivers low-power radiofrequency energy in 2-minute applications to each renal artery at 4–6 points along its length, in a spiral pattern.
Sections 2.3 and 2.4 describe efficacy and safety outcomes from the published literature that the Committee considered as part of the evidence about this procedure. For more detailed information on the evidence see the overview
2.3.1 A randomised controlled trial of 100 patients treated by renal artery denervation (n = 49) or unchanged medical therapy (n = 51) reported an average reduction in blood pressure of 32/12 mmHg and an increase of 1/0 mmHg respectively at 6-month follow-up (p < 0.0001 for both systolic blood pressure [SBP] and diastolic blood pressure [DBP] in the treatment group compared with p = 0.83 for SBP and p = 0.77 for DBP in the control group).
2.3.2 A case series of 153 patients reported a mean reduction in blood pressure of 25/11 mmHg at 6 months (n = 86), 23/11 mmHg at 12 months (n = 64), 26/14 mmHg at 18 months (n = 36) and 32/14 mmHg at 24 months (n = 18) (within-patient changes in both SBP and DBP from baseline were p < 0.0001 at all time points except at 24 months [p = 0.002]).
2.3.3 The Specialist Advisers listed key additional efficacy outcomes as reduction in cardiovascular morbidity and mortality, improvement in the parameters of renal function and regression in left ventricular mass.
2.4.1 Renal artery dissection was reported in 1 patient in the case series of 153 patients: this was stented with no adverse sequelae.
2.4.2 The following serious adverse events (requiring admission to hospital) were reported in 1 patient treated by renal artery denervation in the randomised controlled trial of 100 patients: nausea, oedema, and a hypotensive episode requiring a reduction in antihypertensive medication (timing of events not stated). Patients in the unchanged medical therapy group experienced the following serious adverse events (requiring admission to hospital): transient ischaemic attack in 2 patients and angina requiring a coronary stent in 1 patient (timing of events not stated).
2.4.3 The case series of 153 patients reported that 1 patient had bilateral flank pain which required analgesia (ibuprofen) for several months before it resolved.
2.4.4 The Specialist Advisers considered theoretical adverse events to include renal artery perforation, late stenosis or promotion of atheroma in the renal artery in the long term, sodium depletion and hypotension.
2.5.1 The Committee was mindful of the difficulties in treating patients with drug-resistant hypertension and the serious risks these patients face from uncontrolled high blood pressure. It considered sympathetic denervation of the renal artery to be a promising procedure, which might offer benefit to many patients, but a larger evidence base of well-designed trials is required.