Influence of CT on radiologic utilization in The Netherlands.

The authors studied the influence of computed tomography (CT) on radiologic utilization in The Netherlands. Twenty-six hospitals with a CT scanner were compared with 27 hospitals without on the basis of number of radiologic procedures per clinical patient from 1977 to 1984. Changes in average length of hospitalization were also considered. The number of procedures decreased in hospitals with CT scanners (-9%), in contrast to hospitals without (+10%). The influence of CT on average length of stay appeared minimal. Although this study was limited, the authors believe that use of CT influenced changes in radiologic utilization.

Renovascular hypertension: the small kidney updated.

We report the results of treatment in 57 patients with renovascular hypertension associated with one poorly perfused, small kidney with less than 25 per cent of total 131I-hippurate uptake shown by renography. Arteriography in 29 patients demonstrated occlusion of the artery of the small kidney, and in 28 there was stenosis. In addition, 25 patients had stenosis of the artery supplying the larger contralateral kidney. Stenosis of the arteries of the contralateral kidneys was dilated by percutaneous transluminal arterioplasty in all but one of the 25 patients with bilateral disease of the artery, stenosis of the small kidney could be dilated successfully by percutaneous transluminal arterioplasty in 22 of the 28 patients, and cure or improvement of blood pressure was achieved in 12 of them. Percutaneous transluminal arterioplasty of occluded arteries was generally unsuccessful. In 17 patients with unilateral disease not manageable by percutaneous transluminal arterioplasty, nephrectomy of the small kidney improved blood pressure control without significant deterioration of renal function. Renal function improved in 10 patients with bilateral lesions treated by nephrectomy of the small kidney in combination with contralateral percutaneous transluminal arterioplasty. Histological examination of excised kidneys showed large infarcts or several cholesterol emboli whether percutaneous transluminal arterioplasty had been attempted or not. After observation periods ranging from two to 79 months, 48 patients were normotensive (21 without and 27 with medication) and nine patients were still hypertensive even with medication. This study showed that by using percutaneous transluminal arterioplasty initially if possible, supplemented with nephrectomy and/or medication, normotension without loss of renal function or immediate serious complications could be obtained in the majority of these severely hypertensive patients.

Renovascular hypertension identified by captopril-induced changes in the renogram.

Radioisotope renography was performed in 21 patients with hypertension and unilateral renal artery stenosis with and without premedication with 25 mg of captopril, and the results were compared with the effect of percutaneous transluminal angioplasty on the blood pressure, assessed 6 weeks after angioplasty. Angioplasty caused a considerable decrease in blood pressure in 15 of the 21 patients. In 12 of these 15 patients, captopril induced changes in the time-activity curves of the affected kidney only, suggesting deterioration of the excretory function of that kidney, while the function of the contralateral kidney remained normal. After angioplasty the asymmetry in the time-activity curves diminished despite identical pretreatment with captopril. Such captopril-induced unilateral impairment of the renal function was not seen in the six patients with unilateral renal artery stenosis whose blood pressure did not change after percutaneous transluminal angioplasty or in 13 patients with hypertension and normal renal arteries. The functional impairment of the affected kidneys was characterized by a decrease of 99mTc-diethylenetriamine pentaacetic acid uptake and a delay of 131I-hippurate excretion, while the 131I-hippurate uptake remained unaffected. These data are in agreement with a reduced glomerular filtration rate and diuresis during preservation of the renal blood flow, changes that can be expected after converting enzyme inhibition in a kidney with low perfusion and an active, renin-mediated autoregulation of the glomerular filtration rate. These data suggest that functional captopril-induced unilateral changes, shown by split renal function studies with noninvasive gamma camera scintigraphy, can be used as a diagnostic test for renovascular hypertension caused by unilateral renal artery stenosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Renography with captopril. Changes in a patient with hypertension and unilateral renal artery stenosis.

In a 56-year-old man with severe familial hypertension and unilateral renal artery stenosis, captopril induced striking changes in the renograms of the affected kidney. After injection of orthoiodohippurate sodium I 131, the uptake phase was unchanged but the later curve showed continuous accumulation. In contrast, the uptake of technetium Tc 99m diethylenetriamine pentracetic acid was abolished. These changes are compatible with a cessation of filtration and maintenance of renal blood flow. After balloon dilatation of the stenosis, the blood pressure became lower, and these changes could no longer be demonstrated. The captopril renogram may provide useful information on the dependency of hypertension on unilateral renal artery stenosis.

Follow up study of 70 patients with renal artery stenosis treated by percutaneous transluminal dilatation.

Between April 1978 and April 1981, 70 patients with hypertension and renal artery stenosis were treated by percutaneous transluminal arterial dilatation. Selection of the patients was based solely on arteriographic criteria. Arteriography after dilatation showed considerable widening of the stenosed area in all patients. In 65 patients the effect of treatment on the blood pressure was assessed during follow up periods of one to four years. In 14 of these patients the hypertension was cured, in 29 it was improved, and in 22 there was no change. Patients with fibromuscular lesions benefited distinctly more than did those with atheromatous stenosis, only one of the 21 patients with fibromuscular lesions showing no change as compared with 21 of the 44 patients with atheromatous lesions. The only serious complication encountered was microcholesterol emboli, which developed in two patients with severe atheromatous lesions of the aorta. In the atheromatous group age and overall renal function had no influence on the blood pressure response. In the subgroup of patients with a unilateral lesion the renal vein renin ratios and asymmetrical curves obtained by renography had only a very limited predictive value. In experienced hands percutaneous transluminal arterial dilatation is relatively safe, and this study suggests that it should be attempted in all patients with renal artery stenosis. Only in patients with severe atheromatosis of the aorta should the risk associated with the catheterisation be weighed against the 50% or so chance of benefit from the procedure.

Intraluminal dilatation of renal artery stenosis.

1. In 13 patients with hypertension and renal artery stenosis the stenosis was dilated by an intra-arterial balloon catheter under local anaesthesia. 2. In all but one instance arteriography after the dilatation showed considerable widening of the stenosed area. 3. Six patients had a temporary increase of serum creatinine that lasted only a few days. 4. In seven patients, who had a prolonged transit time at renography, this marker of renal blood flow improved after the dilatation. 5. The effect of the dilatation on the blood pressure in this group of patients, selected on arteriographic criteria only, was variable, but comparable with results of renovascular surgery. 6. Dilatation of renal artery stenosis by an intra-arterial balloon catheter is a promising treatment for patients with hypertension and renal artery stenosis. It is a rapid procedure needing only local anaesthesia. Complications in our experience so far are minor.