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J J Beutler

Publications and source records attributed to J J Beutler.

36 records · Page 2Linked to original sources
PubMed1997

Renal artery stenosis: detection and quantification with spiral CT angiography versus optimized digital subtraction angiography.

PURPOSE: To compare spiral computed tomographic (CT) angiography with optimized digital subtraction angiography (DSA) for accurate detection and quantification of renal artery stenosis. MATERIALS AND METHODS: In 71 consecutive patients with possible renovascular hypertension, spiral CT angiography was performed of the renal arteries before DSA. Optimized DSA (performed with projection angles calculated from axial spiral CT source images) was used as the standard. Two independent observers evaluated spinal CT angiograms for the presence and grade of renal artery stenosis. Sensitivity, specificity, and interobserver variability were calculated. RESULTS: With spiral CT angiography, all 166 renal arteries and accessory arteries were identified correctly by both reviewers. Overall sensitivity and specificity for assessment of stenoses of grade 0 (none), grade 1 (1%-49%), grade 2 (51%-99%), and grade 3 (occlusion) were 97% and 100%, 92% and 98%, 96% and 96%, and 100% and 100%, respectively. Agreement was strong between spiral CT angiographic and DSA findings in assessment of all grades of stenosis (kappa coefficient, 0.9 and 0.9, respectively) for the two observers. CONCLUSION: Spiral CT angiography enabled accurate assessment of renal artery stenosis in patients with possible renovascular hypertension and may assist in selecting patients for interventional treatment.

Adult↗
PubMed1996

Atherosclerotic renal artery stenosis: ostial or truncal?

PURPOSE: To evaluate a discrepancy between the location of renal artery stenoses on intraarterial digital subtraction angiographic (DSA) images and that on spiral computed tomographic (CT) angiograms. MATERIALS AND METHODS: The spiral CT angiograms and intraarterial DSA images of 40 consecutive patients with atherosclerotic renal artery stenoses were examined retrospectively. Stenoses were classified as truncal or ostial. The atherosclerotic changes in the abdominal aorta were graded. RESULTS: Fifty-eight stenoses were demonstrated. In 48 ostial stenoses, there was no discrepancy in the location of the stenoses on spiral CT angiograms and DSA images. In 10 patients, spiral CT angiography showed an ostial lesion, whereas DSA demonstrated an apparent truncal lesion. Most of these stenoses ("pseudotruncal" ostial stenoses) were in patients with severe aortic atherosclerotic disease. CONCLUSION: A renal artery stenosis at or within 10 mm of an atherosclerotic aorta at DSA may be diagnosed as an ostial stenosis.

Adult↗
PubMed1995

Transluminal vascular stent for ostial atherosclerotic renal artery stenosis.

We implanted transluminal stents in 24 hypertensive patients with a critical atherosclerotic ostial renal artery stenosis (28 arteries). Immediate revascularisation was successful in all. Follow-up angiography at 6 months, available in 18 patients, revealed restenosis twice. In another patient restenosis was suspected and confirmed by angiography at 2 months. Hence, the total restenosis rate was 3 of 19 patients (16%) and 3 of 23 arteries (13%). Two patients developed renal insufficiency due to cholesterol embolism. In the remaining 22 patients renal function improved (n = 8) or stabilised (n = 14). Although all had to resume antihypertensive treatment, blood pressure normalised in 15 patients, improved in one, remained unchanged in five and worsened in one.

Aged↗
PubMed1992

Comparative study of the effects of furosemide, ethacrynic acid and bumetanide on the lithium clearance and diluting segment reabsorption in humans.

The effect of intravenous administration of the loop diuretics bumetanide, furosemide and ethacrynic acid on lithium (Li) clearance (CLi) and diluting segment reabsorption was studied in seven healthy water-loaded men. According to the increments in minimal urine osmolality (Uosm), ethacrynic acid (which increased Uosm from 59 +/- 4 to 233 +/- 3 mOsmol/kg) had the strongest inhibiting effect on diluting segment reabsorption, whereas that of furosemide and especially bumetanide was significantly less pronounced (rise in Uosm from 56 +/- 3 to 222 +/- 4 and 56 +/- 4 to 192 +/- 2 mOsmol/kg, respectively). In contrast, ethacrynic acid induced a significantly smaller rise in CLi (approximately 14% of the filtered load of Li) than furosemide and bumetanide, which increased Li excretion by approximately 23% and approximately 24% of its filtered load. The observation that the loop diuretic with the most pronounced inhibiting effect in the diluting segment had the smallest effect on CLi makes is unlikely that the increase in CLi induced by loop diuretics is predominantly effected in Henle's loop.

Adult↗
PubMed1991

Response of urinary angiotensin to challenges of the renin-angiotensin system.

Angiotensin has an intrarenal action which may not parallel its action in the general circulation. We investigated whether the urinary excretion rates of angiotensin I and II (UV-AI, UV-AII) can be used as a marker of renal production. We therefore measured UV-AI, UV-AII, plasma angiotensin I and II (PAI, PAII), and plasma renin activity (PRA) in healthy subjects under conditions influencing the renin-angiotensin system: captopril injection (n = 7), enalapril treatment (n = 9), furosemide infusion on high and low sodium intake (n = 6), indomethacin treatment (n = 8), and head-out water immersion (three sodium intakes). After captopril (acute) and enalapril (chronic), PAI and PRA increased, PAII decreased, but neither UV-AI nor UV-AII changed. During furosemide infusion, PAI, PAII, PRA, as well as UV-AI and UV-AII increased. During indomethacin treatment, PAI, PAII, and PRA decreased, whereas UV-AI and UV-AII did not change consistently. Sodium restriction increased PAI, PAII, and PRA, but did not alter UV-AI and UV-AII. Head-out immersion decreased PAI, PAII, and PRA, but did not change UV-AI and UV-AII. The relative constancy of the urinary AI and AII excretion rates makes it doubtful whether urinary angiotensins reflect changes of renal angiotensin production.

Adult↗
PubMed1990

Does lithium clearance reflect distal delivery in humans? Analysis with furosemide infusion.

Fractional excretion of lithium (FELi+) has been proposed as an index of fluid delivery to the distal nephron. The increase in FELi+ after the "loop diuretic" furosemide indicates that this postulate may not be valid unless furosemide acts in the proximal tubules. We studied the effect of furosemide (40 mg iv as bolus, followed by 20 mg/h infusion for 90 min) in eight healthy male subjects during maximal water diuresis. Special care was taken to exactly replace urinary losses. Furosemide greatly increased fractional excretion of sodium, from 1.3 +/- 0.4 to 27.8 +/- 3.9%, and water, from 14.2 +/- 1.7 to 38.2 +/- 3.7% (P less than 0.01). There was a disproportionately large increase in FELi+ from 30.3 +/- 3.0 to 53.7 +/- 2.9% (P less than 0.01), whereas fractional excretion of some other alleged proximal markers increased to a lesser extent. Lysine vasopressin, infused at the end of the experiment (n = 7), caused only a small increase in urine osmolality from 225 +/- 17 to 241 +/- 17 mosmol/kg (P less than 0.01), indicating that medullary hyperosmolality had been largely abolished. The most likely explanation of these results is that furosemide has a moderate action in the proximal tubules, and at the same time inhibits preexistent lithium absorption in Henle's loop. In addition, the large difference between FELi+ and maximal urine flow remaining after furosemide suggests that, despite the decreased medullary osmotic gradient, water backdiffusion is unaltered by furosemide or that lithium concentration in the proximal tubule is changed by furosemide.

Diuresis↗
PubMed1990

Renal hemodynamic and tubular response to furosemide in man during normal and restricted sodium intake.

To investigate the factors determining the natriuretic response to furosemide (F) during Na restriction, we performed clearance studies in 7 healthy humans on a daily Na intake of 200 and 20 mmol. The maximum urine flow during water loading (Vmax) and simultaneous F administration was used as index of tubular fluid output from the proximal tubules. The F-induced natriuresis was only moderately reduced during Na restriction (Na excretion on low vs. normal Na intake: 4.28 +/- 0.25 vs. 4.94 +/- 0.25 mmol/min; p less than 0.05). The diminished natriuresis was mainly due to a significant fall in Na delivery to Henle's loop of 0.51 +/- 0.10 mmol/min which was either caused by a decrease in filtered Na load or a rise in fractional proximal reabsorption. Fractional distal Na reabsorption was less suppressible by F during Na restriction, but this contributed relatively little (0.15 +/- 0.11 mmol/min) to the total reduction in Na excretion (0.66 +/- 0.10 mmol/min). The F-induced increases in uric acid, phosphate, and bicarbonate excretion suggest an additional proximal site of action of F. This was confirmed by a rise in lithium clearance (CLi), another alleged index of tubular fluid delivery from the proximal tubules. However, the magnitude of the rise in CLi to values markedly exceeding Vmax suggest that CLi overestimates tubular fluid delivery to Henle's loop during F administration.

Adult↗
PubMed1990

Renal actions of theophylline and atrial natriuretic peptide in humans: a comparison by means of clearance studies.

The hypothesis that the methylxanthine theophylline and atrial natriuretic peptide (ANP) have similar actions in the kidney was tested. Doses of equal natriuretic potency were administered to seven healthy men during maximal water diuresis. Theophylline (1.2 mg/kg/min) increased sodium excretion to 3-fold, increased glomerular filtration rate and filtration fraction and had no effect on estimated renal plasma flow. Increments were also found in maximal urine flow, distal delivery index and fractional lithium clearance. Diluting segment reabsorption index decreased, and minimal urine osmolality increased. ANP, of which the dose was low (0.01 micrograms/kg/min), had similar effects on sodium excretion, glomerular filtration rate, filtration fraction, minimal urine osmolality and diluting segment reabsorption index, but it decreased estimated renal plasma flow and had no effect on distal delivery and fractional lithium clearance. In a third clearance study ANP was infused after 3 days of treatment with theophylline. The only difference observed was that theophylline prevented the ANP-induced fall in estimated renal plasma flow. Theophylline did not enhance the natriuretic effect of ANP nor its effect to stimulate urinary cyclic guanosine monophosphate. Pretreatment with theophylline had raised plasma renin activity, but the effect of ANP to lower plasma renin activity was not diminished. Our observations agree with the idea that theophylline and ANP act via common mechanisms in the kidney. However, ANP effects are independent of theophylline's action.

Administration, Oral↗
PubMed1989

Blunted natriuretic response and low blood pressure after atrial natriuretic factor in early cirrhosis.

We compared the natriuretic response to a standard dose of atrial natriuretic factor in nine patients with early cirrhosis (no ascites or edema) with the response in normal subjects displaying a range of baseline sodium excretions due to different sodium intakes (20 mmoles per day, n = 9; 100 mmoles per day, n = 9, and 200 mmoles per day, n = 9). In these normal subjects, sodium output rose, in the same order, from 49 +/- 12 to 177 +/- 26, from 116 +/- 21 to 365 +/- 106 and from 228 +/- 29 to 901 +/- 85 mumoles per min in the first 20 min after 100 micrograms atrial natriuretic factor (human atrial natriuretic factor 99-126). Thus, irrespective of basal excretion, natriuresis rose by at least 2-fold. In the cirrhotic patients, natriuresis rose from 173 +/- 42 to 305 +/- 77 mumoles per min, that is by hardly 1-fold, significantly less than in the normal subjects (p less than 0.01). Renal function studies indicated that atrial natriuretic factor caused less rise in glomerular filtration rate and in fractional sodium excretion. Atrial natriuretic factor induced a fall in blood pressure only in the cirrhotic group, from 130 +/- 4/81 +/- 2 to 108 +/- 4/68 +/- 3 mmHg (p less than 0.001). Plasma atrial natriuretic factor was not low in the cirrhotic patients. Although these data are compatible with a primary disturbance of sodium excretion in early cirrhosis without ascites, such an explanation is complicated by the concomitant drop in blood pressure after atrial natriuretic factor.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Small intra- and large inter-individual variability in lithium clearance in humans.

We report the inter- and intra-individual variability in fractional lithium clearance (CLi), an alleged quantitative index of Na and water delivery from the proximal tubules, in humans (N = 91). The inter-individual variability was large, the variation coefficients at various Na excretion rates ranging between 11% and 19%. The intra-individual variability was small, the relative intra-individual standard deviation for duplicate measurements (N = 33) being 5%. These observations suggest large inter-individual differences in proximal tubular Na reabsorption. To confirm this, we also studied the inter- and intra-individual variability in the maximum urine flow during water diuresis (Vmax), an index of Na delivery to the diluting segment. They were found to be almost identical to the inter- and intra-individual variability in CLi, and fractional CLi and Vmax correlated strongly (r = 0.83, P less than 0.001). In addition, the inter-individual variability in the fractional clearance of uric acid (CUA), a directional marker of Na reabsorption in the proximal tubules, was large, but the intra-individual variability small. The correlation between fractional CUA and CLi, however, was relatively weak (r = 0.40, P less than 0.01). Although our results do not prove the exact, quantitative validity of the lithium clearance concept, we conclude that the variability in CLi reflects large inter-individual differences in Na handling in the proximal segments of the nephron. Our observations also have implications for the use of the lithium clearance method. The large inter-individual variability in CLi makes the method less suitable to detect subtle differences in CLi in small, unpaired groups of subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1988

Paranormal healing and hypertension.

A prospective randomised trial was carried out to see whether paranormal healing by laying on of hands might reduce blood pressure in essential hypertension and whether such an effect might be due to a paranormal, psychological, or placebo factor. Patients were randomised to three treatment groups: paranormal healing by laying on of hands (n = 40), paranormal healing at a distance (n = 37), and no paranormal healing (controls; n = 38). Healing at a distance and no paranormal healing were investigated double blind. Systolic and diastolic blood pressures were significantly reduced in all three groups at week 15 (mean reduction (95% confidence interval) 17.1 (14.0 to 20.2)/8.3 (6.6 to 10.0) mm Hg). Only the successive reductions in diastolic blood pressures among the groups from week to week were significantly different. Each week diastolic pressure was consistently lower (average 1.9 mm Hg) after healing at a distance compared with control, but on paired comparison these differences were not significant. Probably week to week variations among the groups accounted for any differences noted. In this study no treatment was consistently better than another and the data cannot therefore be taken as evidence of a paranormal effect on blood pressure. Probably the fall in blood pressure in all three groups either was caused by the psychosocial approach or was a placebo effect of the trial itself.

Blood Pressure↗
PubMedDate not supplied

Complications during renal artery stent placement for atherosclerotic ostial stenosis.

PURPOSE: To describe short-term complications during stent placement for atherosclerotic renal artery ostial stenosis. METHODS: Sixty-one arteries in 50 patients were treated with Palmaz stents. Nineteen patients had a single functioning kidney, 23 had a bilateral stenosis, which was stented bilaterally in 11, and 8 had a unilateral stenosis. The complications were grouped as those related to the catheterization procedure, those related to stent placement, and those possibly related to either category. The complications were divided into those with severe clinical significance (SCS), those with minor clinical significance (MCS), and radiological-technical complications (RTC). The stent placement procedures were ordered chronologically according to examination date and the complications were tabulated per group of 10 patients. RESULTS: Five (10%) SCS, 5 (10%) MCS, and 8 (16%) RTC occurred in 50 patients. The catheterization procedure led to 2 SCS, 3 MCS, and 1 RTC. Stent placement gave rise to 7 RTC. Three SCS and 2 MCS could have been related to either catheterization or stent placement. More SCS occurred in the first group of 10 patients than in the following groups. CONCLUSION: Renal artery stent placement for atherosclerotic ostial stenosis has a considerable complication rate and a learning curve is present. The complications related to the actual stent placement were without clinical consequences.

Aged↗
PubMedDate not supplied

Duplex ultrasonography in assessing restenosis of renal artery stents.

PURPOSE: To determine the accuracy and optimal threshold values of duplex ultrasonography (US) in assessing restenosis of renal artery stents. METHODS: Twenty-four consecutive patients with 33 renal arteries that had previously been treated with placement of a Palmaz stent underwent duplex US prior to intraarterial digital subtraction angiography (DSA), which was the reference standard. Diagnostic accuracy of in-stent peak systolic velocity (PSV) and reno-aortic ratio (RAR = PSV renal stent/PSV aorta) in detecting > 50% in-stent restenosis were evaluated by the receiver operating characteristic curve. Sensitivity and specificity were determined using the optimal threshold values, and using published threshold values: RAR > 3.5 and in-stent PSV > 180 cm/sec. RESULTS: Six examinations were technically inadequate. Nine stents had residual or restenosis > 50% at DSA. The two duplex parameters were equally accurate since areas under the curves were similar (0.943). With optimal threshold values of 226 cm/sec for PSV and 2.7 for RAR, sensitivities and specificities were 100% and 90%, and 100% and 84%, respectively. Using the published duplex criteria resulted in sensitivities and specificities of 100% and 74% for PSV, and 50% and 89% for RAR. CONCLUSION: Duplex US is a sensitive modality for detecting in-stent restenosis if laboratory-specific threshold values are used.

Aged↗
PubMedDate not supplied

Spiral CT angiography of the renal arteries: should a scan delay based on a test bolus injection or a fixed scan delay be used to obtain maximum enhancement of the vessels?

PURPOSE: The purpose of this work was to assess the optimal scan delay for spiral CT angiography (SCTA) of the renal arteries in achieving optimal vascular contrast enhancement and to compare the utility of a delay based on these bolus injection versus that of a fixed scan delay. METHOD: Seventy patients underwent renal artery SCTA with a 140 ml bolus of contrast agent injected a 3 ml/s. In 35 patients (Group A), a fixed scan delay of 27 s was used; in the other 35 (Group B), the scan delay was based on the transit time (TTest) of a test bolus injection. The scan delays in this group were set at TTest + 5 s (n = 5), TTest + 10 s (n = 8), TTest + 15 s (n = 4), or TTest + 20 s (n = 18). For all 70 patients, the time intervals between TRA (time to scanning the renal arteries) and TMax (time to maximum aortic enhancement after 140 ml bolus injection) were calculated, after which it was determined in which group of patients TRA occurred closest to TMax. Linear regression and mean squared error (MSE) were used for statistical analysis. RESULTS: For Group A, mean TRA and TMax were 38 and 50 s, respectively. Mean (TRA - TMax) was -12 s with MSE of 185.76. For Group B, mean TRA and Tmax were 45 and 52 s. Mean (TRA - TMax) values were -15, -12, -11, and -1 s for scan delays of TTEST + 5 s, TTEST + 10 s, TTest + 15 s, and TTEST + 20 s, respectively, with MSEs of 253.80, 158.00, 137.50, and 30.00. CONCLUSION: SCTA of the renal arteries was best performed with a scan delay of TTEST + 20 s. However, analysis of our data showed that similar results could be expected with a delay of 44 s.

Adolescent↗
PubMedDate not supplied

The benefit of STent placement and blood pressure and lipid-lowering for the prevention of progression of renal dysfunction caused by Atherosclerotic ostial stenosis of the Renal artery. The STAR-study: rationale and study design.

BACKGROUND: Atherosclerotic renal artery stenosis (ARAS) is associated with progressive loss of renal function and is one of the most important causes of renal failure in the elderly. Current treatment includes restoration of the renal arterial lumen by endovascular stent placement. However, this treatment only affects damage caused by ARAS due to the stenosis and ensuing post-stenotic ischemia. ARAS patients have severe general vascular disease. Atherosclerosis and hypertension can also damage the kidney parenchyma causing renal failure. Medical treatment focuses on the latter. Lipid-lowering drugs (statins) could reduce renal failure progression and could reduce the overall high cardiovascular risk. The additional effect on preserving renal function of stent placement as compared to medical therapy alone is unknown. Therefore, the STAR-study aims to compare the effects of renal artery stent placement together with medication vs. medication alone on renal function in ARAS patients. METHOD: Patients with an ARAS of > or = 50% and renal failure (creatinine (Cr) clearance < 80 mL/min/1.73 m2) are randomly assigned to stent placement with medication or to medication alone. Medication consists of statins, anti-hypertensive drugs and antiplatelet therapy. Patients are followed for 2 yrs with extended follow-up to 5 yrs. The primary outcome of this study is a reduction in Cr clearance > 20% compared to baseline. This trial will include 140 patients.

Angioplasty, Balloon↗