De Novo Renal Artery Stenosis After Renal Sympathetic Denervation

To the Editor: A 59-year-old man was referred to our hospital for resistant hypertension. He had been diagnosed with hypertension 6 years ago and his medical history was unremarkable except for hypertension with no diabetes or cardiovascular disease. His daily drug treatment was valsartan/hydrochlorothiazide 320/25 mg, amlodipine 10 mg, nebivolol 5 mg, and spironolactone 25 mg. His blood pressure was under control until 1 year ago. Numerous drug combinations had been used for controlling hypertension but none were effective. Serology and renal artery duplex ultrasonography revealed normal renal function and normal renal arteries. After exclusion of the secondary causes of hypertension, renal sympathetic denervation (RDN) was planned. The procedure was performed under local anesthesia and a 6 Fr introducer sheath was placed in the right femoral artery. Before performing renal denervation, renal artery angiography revealed absence of renovascular disease (Figure 1). The Symplicity (Medtronic Ardian, Mountain View, CA) catheter was used for renal denervation. Radiofrequency catheter ablation was performed in each renal artery with six denervation points. The procedure continued for about 1 hour and no complications occurred except for a nonocclusive vasospasm of the renal artery, which was resolved with nitroglycerin infusion. The patient's blood pressure was under control after the procedure and he was discharged with valsartan 320 mg, hydrochlorothiazide 25 mg, and nebivolol 5 mg. Five months later, he was admitted to the hospital with the complaints of headache, palpitation, and significant elevation of blood pressure despite the drug therapy. Laboratory measures were in the normal range and renal arterial Doppler ultrasonography showed increased velocities at the origin of the left renal artery (peak systolic velocity >300 cm/s). The patient underwent renal angiography according to findings that showed left renal artery stenosis (RAS) of 90%, which was not resolved with nitroglycerin (Figure 2). The stenosis was treated with a 6.0 × 18 mm stent (RX Herculink Elite Renal Stent System; Abbott Laboratories, Santa Clara, CA) and balloon angioplasty (Figure 3 and Figure 4) and he received dual antiplatelet therapy for 1 month (aspirin 100 mg and clopidogrel 75 mg). His blood pressure decreased to 160/100 mm Hg and his complaints were resolved after 1 week. RDN is generally regarded as a safe procedure with a low complication rate.1 According to the Symplicity HTN-2 and Symplicity HTN-3 trials, the rate of renal artery stenosis after RDN was 1.9% and 0.3%, respectively.2, 3 This procedure is a new treatment strategy for resistant hypertension.4 The first case of RAS was reported in 2012.5 The cases with RAS were frequently diagnosed approximately 6 months after the denervation procedure, with recurrence of hypertension, impairment of renal functions, and pulmonary edema.5 Stenosis after denervation could develop with various mechanisms.5 The energy that is released from the radiofrequency ablation can cause endothelial injury, edema, and spasm of renal artery.4 The damage can induce cell proliferation and lead to neointimal stenotic lesions.5 Formation of de novo RAS after RDN was detected in a few cases. Our case is an example of one that required percutaneous intervention. Second-generation RDN has good results for minimizing vascular injury with low energy radiofrequency delivery, and new technologies are under development.6 The complication rates associated with RDN are still low as additional therapy to conventional antihypertensive medications.6