Natural history of renal artery aneurysm elucidated by repeated angiography and pathoanatomical studies.

The findings from repeated angiographies in 16 female and 5 male patients with altogether 34 renal artery aneurysms were studied. The mean interval between the first and last angiography was 35 months. Seven patients had multiple aneurysms. Two to four angiographies were performed in each patient. They showed no change in 28 aneurysms and slight or minimal enlargement, thrombosis or calcification in the other 6. The clinical course was uneventful except for severe hypertension in 3 patients. No rupture occurred. Eight patients, of whom 5 had solitary, saccular aneurysms, were operated upon. Pathoanatomically, fibromuscular dysplasia or secondarily changed fibromuscular dysplasia was found in 7 of them. Four died of unrelated disease having been followed up for 55-204 months (mean 102 months). Nine were alive and symptomless at the end of follow-up 11-195 months (mean 97 months) after the first angiography. The study supports the view that the risk of rupture of a renal artery aneurysm is very small, and indicates that fibromuscular dysplasia is common even when the angiography shows solitary, saccular aneurysm only.