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Biomedical subjects

B C van Jaarsveld

Publications and source records attributed to B C van Jaarsveld.

At least 19 recordsLinked to original sources
PubMed2000

The effect of balloon angioplasty on hypertension in atherosclerotic renal-artery stenosis. Dutch Renal Artery Stenosis Intervention Cooperative Study Group.

BACKGROUND: Patients with hypertension and renal-artery stenosis are often treated with percutaneous transluminal renal angioplasty. However, the long-term effects of this procedure on blood pressure are not well understood. METHODS: We randomly assigned 106 patients with hypertension who had atherosclerotic renal-artery stenosis (defined as a decrease in luminal diameter of 50 percent or more) and a serum creatinine concentration of 2.3 mg per deciliter (200 micromol per liter) or less to undergo percutaneous transluminal renal angioplasty or to receive drug therapy. To be included, patients also had to have a diastolic blood pressure of 95 mm Hg or higher despite treatment with two antihypertensive drugs or an increase of at least 0.2 mg per deciliter (20 micromol per liter) in the serum creatinine concentration during treatment with an angiotensin-converting-enzyme inhibitor. Blood pressure, doses of antihypertensive drugs, and renal function were assessed at 3 and 12 months, and patency of the renal artery was assessed at 12 months. RESULTS: At base line, the mean (+/-SD) systolic and diastolic blood pressures were 179+/-25 and 104+/-10 mm Hg, respectively, in the angioplasty group and 180+/-23 and 103+/-8 mm Hg, respectively, in the drug-therapy group. At three months, the blood pressures were similar in the two groups (169+/-28 and 99+/-12 mm Hg, respectively, in the 56 patients in the angioplasty group and 176+/-31 and 101+/-14 mm Hg, respectively, in the 50 patients in the drug-therapy group; P=0.25 for the comparison of systolic pressure and P=0.36 for the comparison of diastolic pressure between the two groups); at the time, patients in the angioplasty group were taking 2.1+/-1.3 defined daily doses of medication and those in the drug-therapy group were taking 3.2+/-1.5 daily doses (P<0.001). In the drug-therapy group, 22 patients underwent balloon angioplasty after three months because of persistent hypertension despite treatment with three or more drugs or because of a deterioration in renal function. According to intention-to-treat analysis, at 12 months, there were no significant differences between the angioplasty and drug-therapy groups in systolic and diastolic blood pressures, daily drug doses, or renal function. CONCLUSIONS: In the treatment of patients with hypertension and renal-artery stenosis, angioplasty has little advantage over antihypertensive-drug therapy.

Aged↗
PubMed2000

Stent placement for renal arterial stenosis: where do we stand? A meta-analysis.

PURPOSE: To perform a meta-analysis of renal arterial stent placement in comparison with renal percutaneous transluminal angioplasty (PTA) in patients with renal arterial stenosis. MATERIALS AND METHODS: Studies dealing with renal arterial stent placement (14 articles; 678 patients) and renal PTA (10 articles; 644 patients) published up to August 1998 were selected. A random-effects model was used to pool the data. RESULTS: Renal arterial stent placement proved highly successful, with an initial adequate performance in 98% and major complications in 11%. The overall cure rate for hypertension was 20%, whereas hypertension was improved in 49%. Renal function improved in 30% and stabilized in 38% of patients. The restenosis rate at follow-up of 6-29 months was 17%. Stent placement had a higher technical success rate and a lower restenosis rate than did renal PTA (98% vs 77% and 17% vs 26%, respectively; P <.001). The complication rate was not different between the two treatments. The cure rate for hypertension was higher and the improvement rate for renal function was lower after stent placement than after renal PTA (20% vs 10% and 30% vs 38%, respectively; P <.001). CONCLUSION: Renal arterial stent placement is technically superior and clinically comparable to renal PTA alone.

Aged↗
PubMed1999

In-vitro validation, with histology, of intravascular ultrasound in renal arteries.

OBJECTIVE: To investigate the feasibility of using intravascular ultrasound to characterize normal and diseased renal arteries. MATERIALS AND METHODS: Forty-four renal artery specimens from 21 humans, removed at autopsy, were studied with intravascular ultrasound in vitro. From each vascular specimen, two to four sets of corresponding intravascular ultrasound images and histologic sections were subjected to qualitative analysis. The renal arterial wall was considered normal by intravascular ultrasound when the wall thickness (intima and media) was 0.5 mm or less. On intravascular ultrasound imaging, a distinction was made between bright lesions with or without peripheral shadowing (i.e. calcification). Histological sections were examined and fibromuscular lesions were scored with or without calcifications. Quantitative analysis of a multitude of intravascular ultrasound cross-sections (interval 5 mm) included assessment of the lumen area, vessel area, plaque area and percentage area obstructed. The target site (smallest lumen area) was compared with a reference site (largest lumen area before the first major side branch). RESULTS: Of the 130 corresponding intravascular ultrasound images and histologic sections analysed, 55 were normal and 75 presented a bright lesion on ultrasound; in 31 lesions, peripheral shadowing was involved. The sensitivity of the intravascular ultrasound in detecting calcifications was 87%, and the specificity was 89%. Lumen area reduction at the target site was associated with vessel and plaque area enlargement in eight specimens, with plaque area enlargement in 12 specimens and with a vessel area reduction in 21 specimens. CONCLUSIONS: Intravascular ultrasound is a reliable technique for distinguishing renal arteries with or without a lesion. Both plaque development and local vessel narrowing may result in renal artery stenosis.

Adult↗
PubMed1999

Inter-observer variability in the angiographic assessment of renal artery stenosis. DRASTIC study group. Dutch Renal Artery Stenosis Intervention Cooperative.

OBJECTIVE: To assess inter-observer agreement in the interpretation of renal angiograms. DESIGN: Comparison of the assessment of renal angiograms by three experienced radiologists, who evaluated the number of renal arteries and the presence, location, aspect and severity of a renal artery stenosis. SETTING: General hospital and university hospital serving urban and rural populations. PATIENTS: Patients with difficult-to-treat hypertension referred for diagnostic work-up; 312 angiograms with the intra-arterial digital subtraction technique were obtained from 289 consecutive patients. MAIN OUTCOME MEASURES: Inter-observer agreement was tested for the following parameters: number of arteries per kidney, presence of stenosis, location of stenosis (truncal, ostial), aspect of stenosis (concentric, eccentric, post-stenotic dilatation), severity of stenosis (reduction of lumen diameter in categories of 30%, 40%, etc. to 100%), and overall quality of the angiographic images. Kappa (kappa) values and weighted kappa between the three pairs of radiologists were used as estimates of inter-observer agreement RESULTS: Agreement about the number of renal arteries was reasonable (kappa = 0.50-0.72), as was agreement about the presence of stenosis (kappa = 0.68-0.86). Agreement about stenosis location and aspect was poor (kappa = 0.26-0.47 and kappa = 0.15-0.26, respectively). There was general agreement about the severity of stenosis (weighted kappa = 0.65-0.70), but it was not possible to distinguish between 50 and 60% stenosis or between 60 and 70% stenosis (kappa < 0.40). No correlation was found between agreement on severity of stenosis and the quality of the images. CONCLUSIONS: It is not realistic to make statements about what degree of renal artery stenosis is clinically significant, as long as the intra-arterial angiogram with digital subtraction remains the gold standard. It is likewise risky to rely too strongly on stenosis morphology as visualized by renal angiography in choosing between balloon angioplasty and stent deployment.

Adult↗
PubMed1998

A clinical prediction rule for renal artery stenosis.

BACKGROUND: Renal artery stenosis is a rare cause of hypertension. The gold standard for diagnosing renal artery stenosis, renal angiography, is invasive and costly. OBJECTIVE: To develop a prediction rule for renal artery stenosis from clinical characteristics that can be used to select patients for renal angiography. DESIGN: Logistic regression analysis of data from a prospective cohort of patients suspected of having renal artery stenosis. A prediction rule was derived from the regression model for use in clinical practice. SETTING: 26 hypertension clinics in The Netherlands. PATIENTS: 477 hypertensive patients who underwent renal angiography because they had drug-resistant hypertension or an increase in serum creatinine concentration during therapy with angiotensin-converting enzyme inhibitors. RESULTS: Age, sex, atherosclerotic vascular disease, recent onset of hypertension, smoking history, body mass index, presence of an abdominal bruit, serum creatinine concentration, and serum cholesterol level were selected as predictors. The regression model was reliable (goodness-of-fit test, P > 0.2) and discriminated well between patients with stenosis and those with essential hypertension (area under the receiver-operating characteristic curve, 0.84). The diagnostic accuracy of the regression model was similar to that of renal scintigraphy, which had a sensitivity of 72% and a specificity of 90%. CONCLUSIONS: In the diagnostic workup of patients suspected of having renal artery stenosis, the clinical prediction rule can be considered as an alternative to renal scintigraphy. It can help to select patients for renal angiography in an efficient manner by reducing the number of angiographic procedures without the risk for missing many renal artery stenoses.

Adolescent↗
PubMed1997

The place of renal scintigraphy in the diagnosis of renal artery stenosis. Fifteen years of clinical experience.

BACKGROUND: Renal scintigraphy with radiolabeled pentetic acid (diethylenetriamine pentaacetic acid [DTPA]) or, more recently, mertiatide (mercaptoacetyltriglycine [MAG3]), with or without captopril challenge, is widely recommended as a diagnostic test for renal artery stenosis. OBJECTIVES: To address (1) whether the diagnostic accuracy has been improved by the use of captopril and the introduction of mertiatide and (2) whether a renal scan that shows abnormalities is a useful criterion to select patients for renal arteriography. PATIENTS AND METHODS: A standard diagnostic protocol, using both scintigraphy and arteriography, was followed in 505 consecutive high-risk hypertensive patients who were evaluated for renovascular hypertension at the University Hospital Dijkzigt, Rotterdam, the Netherlands, from 1978 to 1992. RESULTS: Renal artery stenosis (> or = 50%) was present in 263 patients. When the single-kidney fractional uptake was used as a diagnostic criterion, a specificity of 0.90 was obtained at a cutoff value of 35% for the worst kidney in scintigraphy using pentetic acid without captopril challenge (n = 225) and at a cutoff value of 37% after captopril challenge (n = 280). This was associated with sensitivity levels of 0.65 and 0.68, respectively. The difference between the uptake of pentetic acid with and without captopril challenge in the 85 patients who were studied under both circumstances was no more accurate as a predictor of renal artery stenosis. In the 93 patients who were studied with mertiatide as well as with pentetic acid, both after captopril challenge, the diagnostic accuracy was no better with mertiatide than with pentetic acid; mertiatide failed to offer any advantage not only when the single-kidney fractional uptake was used as a criterion, but also with the use of other scintigraphic parameters (eg, time to peak, time to pyelum, overall shape of renographic curve, and kidney size). CONCLUSIONS: The diagnostic accuracy of renal scintigraphy has not been improved by the introduction of mertiatide or by the use of captopril. The usefulness of scintigraphy as a diagnostic test for the presence of renal artery stenosis remains questionable. The physician will always confront either a substantial number of arteriograms that do not show abnormalities when renal scintigraphy is omitted as a screening step or a substantial number of missed diagnoses when a renal scan that shows abnormalities is used as a prerequisite for arteriography.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1997

Reproducibility and validity of quality of life measurements in hypertensive patients on stable medication.

OBJECTIVE: The reproducibility and validity of a hypertension-specific questionnaire and a genetic health questionnaire (the MOS Short-form General Health Survey) were evaluated for measuring the quality of life in a randomized controlled trial comparing balloon angioplasty and long-term medication in patients with renovascular hypertension. METHODS: The health questionnaires were filled out by 97 patients with hypertension on stable medication. The reproducibility of the questionnaires was assessed by intraclass correlation coefficients (ICCs). Pearson's correlation coefficients were calculated between the scales of the questionnaires to evaluate the validity. RESULTS: Medication had been changed to eliminate side-effects in an earlier phase of treatment. Only 7% of the patients reported non-compliance with the medication regime. Most patients suffered from physical symptoms, but the impact of long-term antihypertensive medication on the quality of life was not substantial. The reproducibility was good for most scales (ICC > 0.70), except for the role and social functioning scales. All correlations between the scales of the questionnaires were statistically significant and no contradictory correlations were found. CONCLUSIONS: The health questionnaires together form a reproducible and valid instrument for measuring the quality of life of hypertensive patients on stable medication.

Angioplasty, Balloon↗
PubMed1997

Endothelin and active renin levels in essential hypertension and hypertension with renal artery stenosis before and after percutaneous transluminal renal angioplasty.

OBJECTIVE: To determine whether active renin and endothelin levels in venous plasma differ between patients with renal artery stenosis and patients with primary hypertension. Among the patients with renal artery stenosis we also compared active renin and endothelin levels between subjects who had been cured or whose blood pressure had improved after treatment of the stenosis and those without a beneficial reaction after such treatment. METHODS: We measured immunoreactive endothelin and active renin levels in peripheral venous plasma before and 1 h after angiotensin converting enzyme inhibition in 25 patients with primary hypertension and in 27 patients with hypertension and renal artery stenosis. Percutaneous transluminal angioplasty was performed in 21 patients of the latter group. For 11 patients of this group, hypertension was cured or there was an improvement, whereas 10 other patients did not respond to this treatment. Baseline active renin and endothelin levels were compared between these groups, as were the clinical characteristics of the patients. RESULTS: Baseline endothelin levels were similar in members of the renal artery stenosis [median 3.6 pg/ml (range 1.4-11.7)] and in members of the no stenosis group [5.0 pg/ml (1.5-8.0)]. Also baseline endothelin levels did not differ between members of the successfully treated [3.6 pg/ml (1.8-8.9)] and unsuccessfully treated groups [3.75 pg/ml (1.4-8.3)]. Angiotensin converting enzyme (ACE) inhibition failed to cause a significant change in endothelin level in members of any of the patient groups. Although baseline renin levels differed significantly between members of the renal artery stenosis and no stenosis groups [40.2 microu/ml (0.9-543) versus 13.4 microu/ml (2.5-931), (P< 0.05)], there was no difference in baseline renin levels between the members of successful and unsuccessful groups [25.7 microu/ml (9.2-475.6) versus 65.3 microu/ml (12.3-542.6)]. ACE inhibition caused a significant increase in renin level in members of all groups except the unsuccessfully treated group. CONCLUSIONS: Circulating endothelin levels did not differ significantly among patients with essential hypertension, hypertension with renal artery stenosis and proven renovascular hypertension and, although the renin-angiotensin system was clearly activated in members of the renovascular hypertension group, ACE inhibition did not affect their endothelin levels. These results suggest that endothelin does not play a direct role in the pathophysiology of renovascular hypertension.

Adult↗
PubMed1996

Renal artery stenosis towards the year 2000.

FUNCTIONAL DIAGNOSTIC TESTS FOR SELECTING PATIENTS FOR RENAL ARTERIOGRAPHY: The functional diagnostic tests now available to select patients for renal arteriography, such as captopril-renal scintigraphy and the captopril-peripheral vein renin test, have a high degree of diagnostic accuracy, 70% sensitivity at 90% specificity, but they are still not good enough to assess the large population of hypertensives for renal artery stenosis. The use of the angiotensin converting enzyme (ACE) inhibitor challenge and the introduction of a new pharmacon, technetium-labelled mercapto-triglycine, have not sufficiently increased the value of scintigraphy and further improvement in the near future seems unlikely. THE USE OF CLINICAL CRITERIA TO IDENTIFY HIGH-RISK PATIENTS: A more realistic approach to the diagnosis of renal artery stenosis is to seek simple and sensible clinical criteria to identify high-risk patients. The blood pressure response to 2 months of treatment with a standardized two-drug regimen is a suitable criterion. Interim analysis of an ongoing prospective multicentre study in the Netherlands indicates that the prevalence of renal artery stenosis is as high as 25% in patients who are resistant to the combination of 10 mg amlodipine + 50 mg atenolol, compared with 15% in patients resistant to the combination of 20 mg enalapril + 25 mg hydrochlorothiazide. When drug resistance is used as the selection criterion for arteriography, the total number of cases detected with intra-arterial digital subtraction angiography does not seem to differ according to which of these drug regimens is used. FUTURE POSSIBILITIES: The current enthusiasm for percutaneous transluminal renal angioplasty (PTRA) and stenting may be premature. With further improvement of non-invasive techniques to visualize the renal arteries, such as colour Doppler ultrasound with microparticle contrast enhancement or magnetic resonance angiography, it should become more attractive to follow patients with renal artery stenosis while they are being treated with drugs rather than automatically resorting to PTRA.

Angioplasty↗
PubMed1994

An improved method for the determination of islet amyloid polypeptide levels in plasma.

We describe an improved method for the determination of islet amyloid polypeptide (IAPP) levels in plasma. Plasma is first extracted with acid-acetone, followed by a specific and sensitive radioimmunoassay (RIA) for IAPP using rabbit-anti-human-IAPP serum. Recovery of synthetic IAPP from plasma was 82 +/- 6% (n = 16). Standard samples, prepared in 'hormone-free' serum, were also extracted with acid-acetone. Displacement curves of serially diluted acid-acetone extracted plasma samples were parallel to the standard curve. The lower detection limit of the RIA was 2.3 +/- 0.1 fmol/sample (n = 5). Intra-assay variations for IAPP concentrations of 4, 17 and 32 pM were 16.3% (n = 10), 9.2% (n = 10) and 6.2% (n = 10); interassay variations were 35.9% (n = 14), 19.9% (n = 15) and 15.4% (n = 15), respectively. Non-stimulated IAPP levels ranged from 2.4 to 12 pM (mean 6 +/- 4 pM, n = 10) in healthy control subjects. IAPP was not detectable in type 1 (insulin-dependent) diabetic patients before and after glucagon administration. In type 2 (non-insulin-dependent) diabetic patients basal levels ranged from 2.2 to 14.5 pM and glucagon-stimulated levels ranged from 2.2 to 38.9 pM. The increase in IAPP varied from 0 to 24.4 pM. The anti-human-IAPP serum had full cross-reactivity with rat IAPP (= mouse IAPP). Transgenic mice overexpressing the human IAPP gene showed elevated plasma IAPP levels as compared to (non-transgenic) control mice. It is concluded that the method presented for the determination of IAPP in plasma is reliable and easy to perform, yielding reproducible results.(ABSTRACT TRUNCATED AT 250 WORDS)

Amyloid↗
PubMed1993

Plasma concentrations of islet amyloid polypeptide after glucagon administration in type 2 diabetic patients and non-diabetic subjects.

Islet amyloid polypeptide (IAPP) is the main constituent of pancreatic islet amyloid, observed in the pancreases from patients with Type 2 diabetes mellitus. IAPP is synthesized by the pancreatic beta-cells. In order to study the secretion characteristics of IAPP in Type 2 diabetes mellitus, plasma IAPP was measured during a provocation test with glucagon in 33 Type 2 diabetic patients and 18 non-diabetic subjects. The median fasting IAPP level was 5.7 (range 1.1-13.1) pmol l-1 in the 27 patients treated with oral hypoglycaemic agents and 2.7 (1.9-5.9) in the 6 patients on insulin. In the non-diabetic group fasting IAPP was 5.7 (2.2-10.1). Six minutes after glucagon administration median IAPP rose to 9.4 (1.7-31.0) and 6.1 (5.1-10.2) in the respective diabetic groups, and to 16.8 (4.0-41.0) in the non-diabetic subjects (p << 0.05). The correlation coefficient between change in IAPP and change in C-peptide was 0.68 in the diabetic group. We conclude that intravenous administration of glucagon stimulates IAPP release from the beta-cell. This provocation test is easy to perform and can be used on a large scale in the study of IAPP secretion in Type 2 diabetes mellitus.

Adult↗
PubMed1990

[Fulminant sepsis caused by Streptococcus suis].

A 26-year-old man, in daily contact with pigs was admitted to hospital with septic shock which appeared to be caused by Streptococcus suis type 2 infection. Despite immediate antibiotic therapy a multiple organ failure developed, with ARDS, cardiac failure, disseminated intravascular coagulation and acute renal failure. Streptococcus suis infection is a zoonosis. The bacterium can be isolated from the tonsils of a significant part of the Dutch pig population. Mainly people who are in close contact with pigs or pork become infected. Usually meningitis develops. Sepsis, as this case, is rare and often fatal.

Adult↗