Natural history of renal artery stenosis.

Renal artery stenosis secondary to atherosclerosis is a cause of both hypertension and renal failure. Since ultrasonic duplex scanning can be used to detect the presence of renal artery stenosis, it is possible to use this modality for follow-up purposes. This study was designed to determine the relationship between the degree of renal artery narrowing and its effects on kidney size. Serial measurements of renal length were taken as a part of the prospective duplex ultrasound measurements of renal artery narrowing. Fifty-four patients (22 men and 32 women with a mean age of 65.8 years) were included in the study. There were 101 renal arteries and kidneys available for follow-up (average, 14.4 months; range, 4 to 24 months). The patients had repeat duplex studies every 6 months. There were no kidneys with normal renal arteries or a less than 60% diameter-reducing stenosis that had a decrease in renal length of more than 1 cm during follow-up. In those kidneys with a > or = 60% diameter-reducing stenosis, 26% had a decrease in renal length of greater than 1 cm. The average decrease in length was 1.9 cm (range, 1.2 to 3.4 cm). The estimated risk of a loss of more than 1 cm length was 19% at 1 year. Loss of renal mass is an important consequence of high-grade renal artery stenosis.