Renal Artery Angioplasty / Stenting

Background and indications

Renal artery angioplasty with stenting is an endovascular treatment for hemodynamically significant renal artery stenoses. The two main causes are fibromuscular dysplasia (FMD, typically young women) and atherosclerotic stenosis (elderly, polyarterial patients).

Accepted indications include: renovascular hypertension (severe or resistant HTN with > 60-70% stenosis), renal function deterioration attributable to stenosis, flash pulmonary edema (recurrent), and symptomatic FMD. For atherosclerotic stenosis, indications are more restrictive since the ASTRAL and CORAL trials.

Pre-procedure assessment

Assessment includes renal artery Doppler ultrasound, CT or MR angiography confirming stenosis and degree, complete renal panel (creatinine, GFR, kidney size), and coagulation panel. Trans-stenotic pressure gradient measurement may be performed during the procedure.

Procedure

Under local anesthesia, a catheter is introduced through the femoral or radial artery. Under fluoroscopic guidance, the stenosed renal artery is catheterized and an angioplasty balloon is inflated at the stenosis. For atherosclerotic ostial stenoses, a balloon-expandable stent is systematically placed. For FMD, angioplasty alone (without stent) is generally sufficient. The procedure takes 30 to 60 minutes.

Results and scientific evidence

For fibromuscular dysplasia, angioplasty offers a 70-90% HTN cure or improvement rate, with low restenosis (< 10%). For atherosclerotic stenosis, the ASTRAL (NEJM, 2009; DOI: 10.1056/NEJMoa0905368) and CORAL (NEJM, 2014; DOI: 10.1056/NEJMoa1310753) trials showed no significant stenting benefit over optimal medical therapy in unselected populations. However, specific subgroups (flash pulmonary edema, rapid renal decline, severe bilateral stenosis) benefit from endovascular treatment.

Risks and complications

Puncture site hematoma (3-5%), renal artery dissection (< 2%, usually treated by stenting), cholesterol embolism (2-5% for atherosclerotic lesions), transient renal function deterioration (5-10%, related to contrast and/or micro-emboli). In-stent restenosis occurs in 10-20% at 12 months.

Recovery

4-6 hour monitoring. Return to activities within 48 hours. Dual antiplatelet therapy for 1-3 months then long-term aspirin (if stent). Doppler ultrasound follow-up at 1, 6, and 12 months.

Practical information

The procedure is performed as an outpatient or short inpatient stay depending on the case. It is performed by an interventional radiologist, in coordination with the nephrologist and cardiologist.