Renal sympathetic denervation (RSDN), is a minimally invasive, endovascular catheter based procedure using radiofrequency ablation or ultrasound ablation aimed at treating resistant hypertension.
The process denervates the wall of the renal artery by ablated with radiofrequency pulses or ultrasound to the renal arteries.
Ablation of renal artery nerves causes reduction of sympathetic afferent and efferent activity to the kidney and blood pressure can be decreased.
A prospective, single-blind, randomized, sham-controlled clinical trial failed to confirm a beneficial effect on blood pressure.
The procedure involves access via the femoral artery with advancement of a catheter-mounted device into the renal artery.
The device uses radiofrequency or ultrasound to ablate the renal nerves.
Numerous ablations are applied at a different longitudinal and rotational positions to ensure maximal denervation.
In 153 patients that underwent catheter-based renal denervation: Three-year follow-up data have demonstrated an average blood pressure reduction of -33/-19mm Hg (Symplicity trial).
Office systolic blood pressure reductions typically average around 30 mmHg, reductions observed on ambulatory blood pressure monitoring are typically much smaller, around 10 mmHg.
In the most recent study, Symplicity HTN-3-a prospective, single-blind, randomized, sham-controlled trial in which 535 patients with severe resistant hypertension were randomized to undergo renal denervation or a sham procedure (in a 2:1 ratio).
The results showed no statistically significant difference between renal denervation and the sham procedure.
The Symplicity trials have demonstrated acceptable safety profiles for catheter based renal denervation.
Patients may experience pain during application of radiofrequency pulses, bradycardia, Femoral artery pseudoaneurysm and renal artery dissection.
No damage to renal arteries during delivery of radiofrequency energy has been reported.
Other diseases may be associated with an overactive sympathetic drive and therefore renal denervation could be of benefit:Congestive heart failure (CHF), left ventricular hypertrophy (LVH), atrial fibrillation (AF), obstructive sleep apnea (OSA), and insulin resistance/type 2 diabetes mellitus.
Surgical sympathectomy was a recognized treatment for hypertension, but due to its non-selective nature the side effects of the procedure were poorly tolerated: orthostatic hypotension, palpitations, anhydrosis, intestinal disturbances, loss of ejaculation, thoracic duct injuries and atelectasis.
Resistant hypertension is defined as blood pressure above target (140/90mm Hg) despite concomitant use of three or more anti-hypertensives – one of which should be a diuretic: estimated that 8–10% of people with hypertension fall into this category.
Several commercial devices exist.
The procedure involves endovascular access via the femoral artery with advancement of a catheter-mounted device into the renal artery.
The device uses radiofrequency or ultrasound to ablate the renal nerves.
Typically, numerous ablations are applied at a different longitudinal and rotational positions to ensure maximal denervation.
The procedure does not involve a permanent implant.
Symplicity HTN-1, HTN-2 and HTN-3 trials of patients that underwent catheter-based renal denervation.
Three-year follow-up data have demonstrated an average blood pressure reduction of -33/-19mm Hg.
Symplicity HTN-2, six month follow-up data demonstrated a blood pressure reduction of -32/12 mm Hg in the treated group compared with a change of 1/0 mm Hg in the control group.
Meta-analyses of renal denervation, however have yielded conflicting results.
Symplicity HTN-3, was a prospective, single-blind, randomised, sham-controlled trial in which patients with severe resistant hypertension were randomized to undergo renal denervation or a sham procedure (in a 2:1 ratio). The results showed no statistically significant difference between renal denervation and the sham procedure.
More recent sham-controlled trials suggest renal denervation can lead to lower systolic blood pressure.
Trials have demonstrated acceptable safety profiles for catheter based renal denervation.
Patients may experience pain during application of radiofrequency pulses and intraprocedural bradycardia requiring atropine has also been reported.
Other complications include femoral artery pseudoaneurysm and renal artery dissection.
Imaging has not demonstrated renal vascular damage.