Patients with hypertension after renal artery stenting who do not respond to drug treatment may have another option. Renal sympathetic denervation can help lower blood pressure by desensitising nerve endings in the vascular wall. However, recent studies of this treatment concept have excluded patients with stented renal arteries.
The Journal of Endovascular Therapy presents a proof-of-concept study of 10 patients with renal artery stents who were treated with radiofrequency renal denervation. The study examined office blood pressure and ambulatory blood pressure measurements, medication, and renal assessment at baseline and at three, six and 12 months following the procedure.
In this procedure, a catheter is inserted into the arteries leading to the kidney, and radiofrequency energy is dispensed to a segment of the artery, keeping a safe distance of 5mm from the stented segments. Once the nerve endings are desensitised, the renal sympathetic activity is reduced and decreased blood pressure can result.
Current international guidelines, however, exclude patients with an artery stent because of concern that application of radiofrequency through a metallic stent might induce restenosis or occlusion. Alternate technologies for producing denervation, such as ultrasound, brachytherapy and local drug delivery, are also under clinical investigation.
In this study, a successful response to treatment was considered a reduction of at least 10mm Hg in office blood pressure as well as renal artery patency. Nine of the 10 patients met this goal. The patients showed sustained decreased readings in office blood pressure from baseline to three, six and 12 months. Initial readings averaging about 190/84mm Hg declined to 158/76mm Hg after 12 months. No renal artery restenosis or aneurysm had occurred at one year.
While this article makes a case for the expansion of renal denervation studies to include patients with stents, an accompanying commentary points to other trials of this procedure that have not met with the same success. This issue of the journal also includes a case study outlining complications. Also noted are the recently released six-month results of the SYMPLICITY HTN-3 trial comparing renal denervation against a sham procedure. The results show no significant differences between the two approaches. The commentary urges a case-by-case consideration for renal denervation while further research is conducted.
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