Detection of renovascular hypertension

The prevalence of secondary and curable hypertension

The prevalence of secondary and curable hypertension was studied retrospectively in 1000 patients. The concept of "secondary hypertension" was used when hypertension was combined with a disease which may have affected the individual's blood pressure. When this definition was applied, 47 of the patients displayed some form of secondary hypertension: stenosis of the renal artery in 10, renoparenchymal disease in 21, hydronephrosis in 3, and endocrine hypertension in 13 (8 of the latter were using oral contraceptives). The blood pressure normalized in 11 and improved in 7 of these patients after operative treatment of the underlying disease or, when appropriate, discontinuance of intake of contraceptive pills. The incidence of secondary hypertension in this and other series is low, and the number of patients with curable hypertension is even lower. In the majority of cases, secondary hypertension can be diagnosed by anamnesis, physical examination and simple tests of blood and urine. If this basic investigation can be extended, the incidence of stenosis of the renal artery should be examined in the first place. Hypertension in young patient and in patients who are difficult to treat often justifies a more extensive investigation.

Secondary hypertension in a medical ward

The prevalence of secondary hypertension was evaluated by investigating 400 consecutive patients with arterial hypertension in a medical ward. They were classified into four groups according to the case history. Group A: 104 subjects with therapy-resistant hypertension, group B: 247 patients who had another concomitant disease as the primary reason for admission, group C: 34 patients referred to the ward for basic investigation due to recently diagnosed hypertension, group D: 15 patients with unwanted hypertension was 15.5% in the entire series, and 14.4%, 18.6%, 2.9% and 0% in groups A - D, respectively. Ten patients (2.5%) were operated on, nine of them from group A and one from group B. The findings demonstrate the importance of a careful examination of patients with therapy-resistant hypertension, since they might include subjects whose hypertension can be treated by surgery.

Renovascular hypertension: predicting surgical cure with exercise renography

Renal artery stenosis with resultant renovascular hypertension has attracted clinical attention because the disease is potentially curable and because numerous diagnostic and therapeutic modalities compete for clinical acceptance. An exercise-mediated disturbance of renal hippurate transport was recently described, and has been implicated as having a role in nephrogenic fixed hypertension. To predict the final course of renovascular hypertension before operation we carried out a prospective study with the goal of verifying the predictive value of exercise hippurate scintigraphy. The study was to test the hypothesis that patients with disturbance of renal hippurate transport (pathologic renogram) induced by exercise would have stabilized hypertension and would continue to be hypertensive after operation. Thirty-one patients with hypertension who had unilateral or bilateral renovascular stenosis documented on angiography were referred to rest and exercise hippurate scintigrams before operation. The results of the examinations at rest served as standard and were compared with the exercise scintigrams. In 19 of the 31 (61%) patients a disturbance of transrenal hippurate transport evolved during exercise, whereas 12 (39%) patients failed to respond to exercise with altered hippurate kinetics. Twenty-six patients went on to renovascular operations; five had percutaneous transluminal angioplasty. Revascularization results differed markedly when the blood pressure response of patients with positive results on exercise (abnormal) and patients with negative results on exercise (normal) were compared. Ten of 12 patients with hypertension who had normal exercise renograms were cured. In comparison, blood pressure values were little influenced by therapy in patients with an abnormal response, where 17 of 19 patients continued to have hypertensive disease after therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Multicystic dysplastic kidney: is nephrectomy still appropriate?

We analyzed 25 cases of multicystic kidney to assess the impact of prenatal diagnosis on the management of this condition. The incidence of unilateral multicystic kidney was 1 in 4,300 live births. Of the 23 children with unilateral multicystic kidneys only 3 (13 per cent) had a readily palpable lesion. These findings suggest that multicystic kidney is a more common renal anomaly than was previously recognized and that the majority of cases remained undiagnosed before the advent of prenatal diagnosis. Ultrasound re-evaluation in 11 children suggests that the natural history of multicystic kidneys is towards spontaneous involution. Two kidneys were not identifiable by followup ultrasound. Hypertension and malignancy complicating multicystic kidney are reported infrequently. The literature on hypertension does not generally support the view that multicystic kidney poses a significant risk of hypertension in later childhood or adult life. We believe that the routine removal of multicystic kidneys in infancy is no longer appropriate.

The captopril test for identifying renovascular disease in hypertensive patients

To develop a screening test for identifying renovascular hypertension, the blood pressure and plasma renin activity responses to an oral test dose of captopril were studied in 246 quietly seated hypertensive patients. The following criteria were developed that exploit the hyperresponsiveness of renin secretion in renovascular hypertensive patients: a 60-minute post-captopril plasma renin activity of 12 ng/ml per hour or more and an absolute plasma renin activity increase of 10 ng/ml per hour or more, along with a 150 percent increase in plasma renin activity (or a 400 percent increase if the baseline plasma renin activity was below 3 ng/ml per hour). Retrospectively, the test identified, among 200 hypertensive patients without evidence of renal dysfunction, all 56 patients with proved renovascular disease. In this group, false-positive results occurred only in two of 112 patients with essential hypertension and in six with secondary hypertension. Nine untreated patients had blood pressure levels of less than 160/100 mm Hg. The test was neither as sensitive nor specific in the 46 patients with renal insufficiency. This study demonstrates that the renin response to oral captopril is a useful screening test for identifying patients with unilateral or bilateral renovascular disease. Since the test also characterizes the renin dependency of the hypertension, it may have other diagnostic and therapeutic uses.

Predictive value of radionuclide methods in the diagnosis of unilateral renovascular hypertension

The validity of noninvasive (iodine-131 iodohippurate renogram, iodine-131 ortho-iodohippurate clearance, indium-113m EDTA--technetium-99m DTPA sequential renal scan) and invasive (xenon-133 washout) radionuclide screening tests was evaluated in the diagnosis of 105 patients with unilateral renovascular hypertension (RVH) and in 45 patients with essential hypertension (EH). In RVH positive findings on the stenosed side were noted in 73% of renograms, 73% of o-iodohippurate-clearance tests (N = 22), 81% of sequential renal scans, and 90% of xenon-washout studies (N = 67). In a subgroup of 55 retrospectively selected patients with normal or improved blood pressure following renovascular surgery, the preoperative findings had been positive on the stenosed side in 78% of renograms, 75% of o-iodohippurate-clearance tests (n = 20), 85% of sequential renal scans, and 93% of xenon-washout studies (n = 23). The sequential renal scan appears to be a sufficiently reliable method in noninvasive screening for unilateral RVH, although invasive xenon-washout studies show a higher percentage of hemodynamic alterations in the stenosed kidney. o-iodohippurate clearance tests, and in particular xenon-washout studies, can reveal arteriosclerotic lesions in the contralateral, non-stenosed kidney, which may be of importance when the decision for renovascular surgery is pending.

The frequency of secondary hypertension

In a series comprising 482 patients with hypertension requiring treatment 79 percent had to be classified as essential hypertension. Bilateral renal disease was found in 9 percent, unilateral renal disease in 3.3 percent, but only one patient underwent surgery. Renal artery stenosis was found in 24 patients (5 percent), but only 5 (1 percent) were operated on. Two cases of primary hyperaldosteronism and one of phaeochromocytoma were found; in all three surgical intervention was successful. Oral contraceptives had caused the elevated BP in 7 patients (1.5 percent). It is emphasized that the frequency of curable hypertension is still very low and this should be taken into account when routine examination of patients with hypertension requiring treatment is discussed.

Results of nephrectomy in hypertension associated with unilateral renal disease

Nephrectomy has been carried out in 34 patients with hypertension associated with unilateral parenchymal renal disease (28 with unilateral pyelonephritis, 3 tuberculosis, 2 hypoplasia, and 1 adenocarcinoma). In 13 of the patients the blood pressure was corrected, in four it was improved, and in 17 it was unaffected. The intravenous pyelogram (by the infusion technique with nephrotomography if necessary) and renogram give adequate information in most patients with unilateral parenchymal renal disease but may need to be supplemented by aortography, or retrograde pyelography, or divided renal function studies in a few special circumstances. When the function of the damaged kidney is less than 25% of the total (which is well maintained), and the contralateral kidney is intact, nephrectomy is recommended provided the hypertension is significant; success is more likely in younger patients with a short history of hypertension.