Renal denervation for resistant hypertension
There has been very considerable enthusiasm for renal denervation for resistant hypertension in the last few years. However it is not a new idea and I well remember as a young surgeon in the late 60’s carrying out open renal denervation for hypertension under the direction of the renowned nephrologist, Professor Priscilla Kincaid-Smith. Anecdotally there did not appear to be any benefit from this procedure. The development of renal denervation using radiofrequency ablation is a newer minimally invasive approach and early studies suggested that this did produce an improvement in resistant systolic blood pressure. However in the latest edition of the NEJM Bhatt and colleagues report the findings of a very good trial which fails to show any significant improvement in blood pressure. This is accompanied by an excellent editorial on the subject by Messerli and Bangalore.
In this excellent trial, which was a prospective, single blind, randomised, sham controlled trial, patients with severe resistant hypertension were randomly assigned in a two to one ratio to undergo renal artery denervation with the Symplicity catheter or a sham procedure (a renal angiogram). This blinded trial did not show a significant reduction of systolic blood pressure in patients with resistant hypertension at 6 months, compared to the sham control patients. This is a model study and as the authors conclude “renal denervation in the current trial appeared to be safe with no unanticipated side effects, however a significant effect on systolic blood pressure was not observed, further evaluation in rigorously designed clinical trials will be necessary to validate alternative methods of renal denervation or to confirm previously recorded benefits of renal denervation in patients with resistant hypertension.”
It is also relevant that when we transplant a kidney we are transplanting a denervated kidney and in fact in the pioneer days of kidney transplantation there was considerable concern as to whether a denervated kidney could function appropriately. However patients with a transplanted kidney still had problems with elevated blood pressure even if their own kidneys had been removed.
