Renal artery stenosis (RAS) is a potentially curable cause of hypertension and azotemia. Besides intra-arterial renal angiography there are several non-invasive techniques utilized to diagnose patients with suspicion of renal artery stenosis. Removing the stenosis by revascularization to restore unobstructed blood flow to the kidney is known to improve and even cure hypertension/azotemia, but is associated with a significant complication rate.
To visualize renal arteries with x-ray techniques a contrast medium must be used. In a randomized, prospective study the complications of two types of contrast media (CO2 and ioxaglate) were compared. CO2 was not associated with acute nephropathy, but induced nausea and had lower attenuation differences compared to Ioxaglate. Acute nephropathy was related to the ioxaglate dose and the risk was evident even at very low doses if the patients were azotemic with creatinine clearance <40 ml/min.
Evaluating patients for clinically relevant renal artery stenosis can be done utilizing several non-invasive techniques. MRA was retrospectively evaluated and shown to be accurate in detecting hemodynamically significant RAS. In a prospective study of 58 patients, evaluated with four methods for renal artery stenosis, it was shown that MRA and CTA were significantly better than ultrasonography and captopril renography in detecting hemodynamically significant RAS. The standard of reference was trans-stenotic pressure gradient measurement, defining a stenosis as significant at a gradient of ≥15 mmHg. The discrepancies were mainly found in the presence of borderline stenosis.
The outcome of percutaneous revascularization procedures showed a technical success rate of 95%, clinical benefit in 63% of treated patients, 30-day mortality 1.5% and major complication rate of 13%. The major complication rate for patients with baseline serum creatinine >300µmol/l was 32%. Our results compare favorably with published studies and guidelines.