The Long-term Safety and Effect of Renal Denervation

Renal denervation is emerging as a succesful technique in the treatment of high blood pressure particularly for those people who's disease is resistant to drug therapy. It involves insertion of an catheter through the femoral artery and into the renal artery where it delivers a controlled radiofrequency ablation to the renal artery wall. The purpose of this ablation is to interupt the sympathetic nervous system which is inappropriately activated in hypertension. Its beneficial effects on BP reduction has been borne out in a recently published randomised clinical trial which demonstrated a reduction in blood pressure in patients who underwent denervation compared to those managed with medication alone and it is now being used worldwide to manage hypertensive patients. The safety of this procedure has been demonstrated in the peri-operative setting and short term particularly regarding anatomical changes and kidney function. However, its effects have not been demonstrated with invasive imaging or physiological testing in the long term. Therefore, the investigators recognise that a repeat assessment 6 months after denervation using invasive measures (to perform detailed assessments of the effects on aortic, flow and artery stiffness) would be of great benefit in stratifying this technique, which is likely to become widespread in the very near future. The investigators therefore plan to perform denervation in 20 patients and obtain detailed information on kidney and aortic blood pressure and flow. They will then reassess these parameters after 6 months in the same patients to ensure preservation of pressure, flow and energy transfer and document the effects of denervation on vascular stiffness.