The decision on surgery in renal artery stenosis.

Eighty-six hypertensive patients with arteriographic evidence of renal artery stenosis presented between 1968 and 1979. Thirty-nine subsequently underwent surgery and were followed thereafter for at least one year. In 54 per cent blood pressure was reduced to within one standard deviation of the mean for a normal individual of the same sex and age. A further thirty-one per cent of patients were 'improved', but needed hypotensive drugs to maintain blood pressure within this range. In the remaining 15 per cent of patients the operation did not reduce blood pressure. The purpose of the study was to assess our ability to predict this varies surgical outcome using clinical observations and special tests. The latter included measurement of plasma renin concentration in both peripheral vein and renal vein plasma, catheterization of both ureters and studies of the response of blood pressure to brief infusion of saralasin. No single observation or test, no combination of observations or tests and no discriminant function clearly separated patients in whom surgery would succeed from those in whom it would fail. Renal vein renin ratio was the best test; all patients with a ratio greater than 2.0 underwent successful surgery, but so too did some patients with a lower ratio. We also analysed the factors which had influenced our decision to undertake special investigations in 65 of the 86 patients and, having done these investigations, to recommend surgery in 39. No single factor seemed to have had overriding importance in making these decisions.