Ischemic Renal Disease

Renal artery stenosis is now recognized as an important cause of renal insufficiency and end-stage renal disease. Ischemic nephropathy is defined as chronic renal impairment secondary to hemodynamically significant renal artery stenosis.

The most common cause of vascular disease is bilateral atherosclerotic renal artery stenosis. Approximately %15 of patients with end-stage renal disease who are older than age 50 years have ischemic renal disease. The incidence of renal vascular disease is even higher, 30% to 40%, in patients with evidence of coronary, cerebral, or peripheral vascular disease.

The diagnosis of atherosclerotic ischemic nephropathy should be considered in patients with significant risk factors. The urinalysis is usually benign, with few cells and mild to moderate proteinuria. These patients may have nephrotic-range proteinuria, although this is unusual. The natural history of atherosclerotic renal vascular disease is that of progression. Angiographic progression of renal artery stenosis has been documented in 40% to 50% of patients over a period of 2 to 5 years. With progression, atherosclerotic renal vascular disease can lead to end-stage renal disease. Many patients who were classified as having hypertensive nephrosclerosis may have had progressive renal vascular ischemic nephropathy. Ischemic nephropathy as the cause of renal insufficiency is probably underestimated. The diagnosis of ischemic nephropathy depends on finding of significant renal artery stenosis and proving that these lesions are the cause of renal impairment. Currently, there are no tests that have been shown to be predictive of improvement in renal function after correction of renal artery stenosis. Furthermore, tests or the diagnosis of renovascular hypertension such as angiotensin-converting enzyme inhibitor renography, is not reliable in patients with renal dysfunction. Discrepancy in renal size on ultrasound is an important clue for considering the diagnosis. Duplex Doppler ultrasonography is a good screening test, but it is highly operator dependent, may be technically difficult, and is time consuming.

Magnetic resonance angiography appears to be an effective noninvasive test to detect the stenosis of proximal renal blood vessels. However, it is unreliable in the diagnosis of renal artery branch stenosis. The gold standard test for the diagnosis of ischemic nephropathy is renal arteriography. However, the risks of arteriography include contrast medium-induced acute renal failure, atheroembolic renal disease, and irreversible loss of renal function.

These patients usually have underlying renal insufficiency and are at an in creased risk for contrast medium induced acute renal failure, which may be prevented by hydration, use of nonionic contrast, or CO2 angiography.