Effects of leukotrienes on bronchial secretions

To evaluate the reliability of Doppler-ultrasonography in identifying children with renal artery stenosis among those with hypertension, we compared Doppler ultrasonography results in 29 hypertensive children (mean age: 8.3 +/- 4.7 years) with angiography. Doppler-ultrasonography and arteriography were performed within a period less than two months. First, we established normal values in 40 normotensive children (mean age: 8.4 +/- 4.5 years). The diagnosis of renal artery stenosis was settled when maximal systolic velocities where > or = to 1.70 m.s-1. Peak systolic velocities values of Doppler-ultrasonography were significantly higher in patients with proven angiographic renal artery stenosis (3.56 +/- 0.70 m.s-1) than in hypertensive patients with normal renal arteries at angiography (1.02 +/- 0.29 m.s-1, p < 0.0001), and than in normotensive healthy children (1.05 +/- 0.33 m.s-1, p < 0.0001). We observed 3 false negative and 2 false positive diagnoses with Doppler-ultrasonography. Of the 3 false negatives, one had a stenosis on a right and posterior segmental artery and the other had bilateral and multiply intra-renal artery stenosis with few hemodynamic significance. The 2 false positives were due to a sinuous main renal artery and to a technical mistake, respectively. In another patient, Doppler-ultrasonography revealed a tight main renal artery stenosis, not detected by arteriography. Renal artery stenosis was subsequently confirmed by a second arteriography. Our results showed a sensitivity of 88%, a specificity of 93%, a positive predictive value of 92% and a negative predictive value of 89%, demonstrating the reliability of Doppler-ultrasonography for the diagnosis of renal artery stenosis in hypertensive children. With the use of a rigorous methodology and the increasing experience of the operators, diagnostic errors of renal artery stenosis are currently avoidable. Nevertheless, it is not excluded that intra-renal artery stenosis with few hemodynamic significance might be missed by Doppler-ultrasonography.     

Maternal renal artery blood flow velocimetry in normal and hypertensive pregnancies

OBJECTIVE: To investigate the effect of normal pregnancy and hypertensive disorders of pregnancy on the maternal renal artery Doppler blood flow velocity indices. METHODS: The patient material consisted of 30 normal pregnant women, 29 women with pregnancy induced hypertension, 43 women with preeclampsia and 22 pregnant women with chronic hypertension. Blood flow velocities in the segmental renal arteries from the right kidney were analysed by pulsed and color Doppler. The systolic/diastolic (s.d.) ratio, resistance index (RI) and pulsatility index (PI) were used for Doppler waveform analysis. RESULTS: In all of the groups of hypertensive pregnant women renal artery Doppler indices were significantly lower compared to the normal pregnant women group. There was a significant negative relationship between renal artery PI and mean arterial pressure in the preeclampsia group and in the chronic hypertension group. CONCLUSION: The present results demonstrate that the mechanism of renal autoregulation in preeclampsia might be altered, leaving glomerulus unprotected from increased blood pressure. It seems that the concept of renal vasoconstriction in preeclampsia might be disputed and needs further investigation.     

The Dutch Renal Artery Stenosis Intervention Cooperative (DRASTIC) Study: rationale, design and inclusion data

RATIONALE: Renal artery stenosis may lead to renovascular hypertension, risking multiple organ damage including damage to the contralateral kidney. Progression of stenosis may impair the function of the affected kidney. It is important to identify individuals with this disease among hypertensive patients. The first aim of the Dutch Renal Artery Stenosis Intervention Cooperative (DRASTIC) study is to assess the prevalence of renal artery stenosis in patients with well-defined forms of drug-resistant hypertension, and to determine the predictive value of clinical characteristics and diagnostic tests in these pre-selected patients. With regard to treatment, the effect of renal angioplasty on hypertension is disappointing in atherosclerotic stenosis and technical failure frequently occurs. Therefore, the second aim is to compare the effects of balloon angioplasty and antihypertensive medication on blood pressure in patients with atherosclerotic renal artery stenosis. DESIGN HYPERTENSIVE: patients receiving standard antihypertensive medication in whom diastolic blood pressure remained > or =95 mmHg during three consecutive visits to the outpatient clinic underwent full diagnostic work-up, including renal arteriography. The prevalence of renal artery stenosis in this well-defined patient group was then established, and the predictive value of the various diagnostic tests was assessed. Patients with an atherosclerotic renal artery stenosis of > or =50% were then randomly assigned to balloon angioplasty or to treatment with antihypertensive drugs. After 1 year of intensive follow-up of blood pressure and renal function, re-arteriography was performed. CONCLUSION: In total, 1205 patients have been included in the study, about 500 have received diagnostic work-up, and it is expected that 100 patients will be randomly assigned for renal angioplasty or medical treatment.     

Unexpected death of psychiatric patients: suicide, misadventure, accident or unsolved mystery?

BACKGROUND: Because of the wide range of recommended threshold values for carotid stenosis graduation we performed a prospective study to determine interobserver and interequipment variability of quantitative blood flow velocity measurements. PATIENTS AND METHODS: We recorded absolute blood flow velocities and velocity ratios in 21 patients with carotid artery stenosis using two colour coded duplex ultrasound systems an ATL Ultramark 9 HDI, and a Hewlett Packard SONOS 2500 system. The ATL system was used for the interobserver variation study, where each patient was examined twice on the same day. The Doppler angle was recorded together with blood flow velocities (peak systolic velocity and mean maximum velocity from the velocity-time-integral both in the stenosis jet and 4-5 cm distally in the cranial portion of the internal carotid artery off poststenotic turbulences). RESULTS: The ATL system generated significantly higher blood flow velocity values as compared with the HP system (218 +/- 156 cm/s vs. 169 +/- 114 cm/s; p < 0.001). The Mean Velocity Ratio (the ratio of intrastenotic Vmean and poststenotic Vmean) was constant with both duplex systems. The HP system yielded 10% (Cl, 7-13%) lower predicted stenosis estimates than the ATL system with Vmax as the stenosis criterion. The stenosis estimates calculated from Mean Velocity Ratio values did not differ significantly. The 95% Cl for predicted diameter reduction between two observer was 13.6% (Vmax) and 15.4% (Mean Velocity Ratio). CONCLUSION: Because of significant interequipment differences of colour coded duplex ultrasound systems we recommend calculation of the Mean Velocity Ratio to avoid interpatient and interequipment variation of absolute flow velocities. According to our interobserver variability study, a change of more than 15% diameter reduction on follow-up examinations indicates disease progression or regression.     

Diagnosis of renovascular disease by extra- and intrarenal Doppler parameters

It is still a matter of debate as to which parameters should be used for noninvasive diagnosis of renovascular disease by renal Doppler sonography (RDS). The accuracy of RDS in the detection of renal artery stenosis (RAS) was tested in 95 consecutive, moderate to severe hypertensive patients (I-II World Health Organization [WHO] stages). Reno-aortic ratio (RAR) for peak systolic velocity (PSV) was also calculated to assist in the diagnosis of significant (>50%) RAS. Paired receiver-operating characteristic (ROC) analysis was plotted for evaluating the relationship between sensitivity and specificity for each parameter. In a subset of 57 kidneys, the influence of blood pressure and age on intraparenchymal parameters was evaluated. Measurements of maximal peak systolic velocity (PSV) at the site of stenosis, RAR for PSV, and minimum acceleration index in the main renal artery showed high accuracy (areas under the ROC curve 0.97, 0.88, and 0.80, respectively). Among intraparenchymal parameters, early systolic acceleration showed the best area under the ROC curve (0.90), but provided a low positive predictive value (29%) and was significantly influenced by blood pressure (multiple r=0.56; p=0.001). Pulsatility and resistive indices were found to be less powerful as absolute values, and both significantly influenced by blood pressure and age (multiple r=0.60 and 0.50; p=0.001, p=0.02, respectively). However, interindividual variance of intrarenal indices should be minimized by calculation of side difference, although this procedure would become misleading or impossible in patients with bilateral RAS or a single kidney, respectively. These results support the use of extraparenchymal parameters for noninvasive detection of RAS, and emphasize that intrarenal parameters cannot be considered as absolute values.     

Quantitative analysis of the technetium-99m-DTPA captopril renogram: contribution of washout parameters to the diagnosis of renal artery stenosis

Retrospective analysis of precaptopril and postcaptopril DTPA renograms from 88 hypertensive patients was performed to refine the quantitative criteria used to diagnose renal artery stenosis (RAS). Of the 88 patients, 45 had RAS and 43 had normal renal arteries at angiography. Using time-activity curves from the essential hypertensive group, diagnostic washout criteria for a positive DTPA renogram were developed. These were based on the 20 and 30 min/peak activity ratios in each kidney. When the washout criteria were retrospectively applied to patient data as a whole, sensitivity and specificity for RAS were 67% and 79%, respectively. When previously described uptake criteria, based on the time to peak activity in each kidney and the GFR ratio between the kidneys, were applied to the same data, sensitivity and specificity for RAS were 89% and 84%, respectively. Quantitative analysis of the DTPA renogram using the time to peak and GFR ratio was both sensitive and specific for RAS. Measurement of 20 and 30 min/peak renal activity ratios did not improve the accuracy of the test.     

Evaluation and management of bilateral renal artery stenosis in children: a case series and review

This report describes the clinical course, diagnostic evaluation and management of six children with bilateral renal artery stenosis (RAS) and concurrent narrowing of the abdominal aorta. Except for one child with active arteritis, the others were asymptomatic. There were no clinical or laboratory features suggesting the etiology of hypertension in four of six patients, and diagnostic procedures, including Doppler duplex ultrasound and captopril scintigraphy, were unreliable in screening for such hypertension. Abdominal aortography and selective renal angiography confirmed the diagnosis of bilateral RAS and associated anatomical alterations of the aorta and its branches. The hypertension was severe and minimally responsive to antihypertensive agents. It was cured or improved after percutaneous transluminal angioplasty (PTA) of three vessels in two children with mid-vessel stenoses, while hypertension persisted after PTA of two mid-vessel stenoses in a third child and one vessel with ostium stenosis in a fourth child. Autotransplantation of seven kidneys in four children resulted in cure of significant improvement of the hypertension. Renal function was preserved in all children during a mean follow-up time of 41 months. Based on illustrative data from these six children, as well as information from a review of the literature, this report discusses the key diagnostic issues and stresses the potential advantages of renal autotransplantation in selected children with this disorder.     

Increased plasma endothelin concentration in atherosclerotic renovascular hypertension

The aim was to investigate circulating levels of immunoreactive endothelin (ir-ET) in atherosclerotic renovascular hypertension (RVH), and to assess the role of the kidneys in its overall plasma concentration. We studied 16 hypertensive patients with renal artery stenosis evidenced by angiography and admitted to hospital for the diagnostic evaluation of RVH by renal vein plasma renin activity (PRA) determinations. The right femoral vein was catheterized to simultaneously measure PRA and ir-ET in both renal veins and inferior vena cava below the origin of the renal veins. RVH was present in 9 patients as indicated by diagnostic PRA renal vein ratios and the remaining 7 patients were considered to have essential hypertension (EH). Patients with RVH showed a marked increase in systemic plasma ir-ET concentration (10.3 +/- 0.9 pg/ml). Despite a significant increase of PRA in the vein of the ischemic (IK) versus the contralateral (CK) kidney in patients with RVH, no significant differences in ir-ET concentration were observed between both kidneys. These results indicate that patients with RVH have increased circulating levels of ir-ET. However, the higher systemic plasma ir-ET do not arise from the renal circulation, since plasma ir-ET is significantly higher in systemic circulation than in renal veins.     

Prospective study of atherosclerotic disease progression in the renal artery

BACKGROUND: The aim of this study was to determine the incidence of and the risk factors associated with progression of renal artery disease in individuals with atherosclerotic renal artery stenosis (ARAS). METHODS AND RESULTS: Subjects with >/=1 ARAS were monitored with serial renal artery duplex scans. A total of 295 kidneys in 170 patients were monitored for a mean of 33 months. Overall, the cumulative incidence of ARAS progression was 35% at 3 years and 51% at 5 years. The 3-year cumulative incidence of renal artery disease progression stratified by baseline disease classification was 18%, 28%, and 49% for renal arteries initially classified as normal, <60% stenosis, and >/=60% stenosis, respectively (P=0.03, log-rank test). There were only 9 renal artery occlusions during the study, all of which occurred in renal arteries having >/=60% stenosis at the examination before the detection of occlusion. A stepwise Cox proportional hazards model included 4 baseline factors that were significantly associated with the risk of renal artery disease progression during follow-up: systolic blood pressure >/=160 mm Hg (relative risk [RR]=2.1; 95% CI, 1.2 to 3.5), diabetes mellitus (RR=2.0; 95% CI, 1.2 to 3.3), and high-grade (>60% stenosis or occlusion) disease in either the ipsilateral (RR=1.9; 95% CI, 1.2 to 3.0) or contralateral (RR=1.7; 95% CI, 1.0 to 2.8) renal artery. CONCLUSIONS: Although renal artery disease progression is a frequent occurrence, progression to total renal artery occlusion is not. The risk of renal artery disease progression is highest among individuals with preexisting high-grade stenosis in either renal artery, elevated systolic blood pressure, and diabetes mellitus.     

Reconstruction of renal artery aneurysms. Vessel morphology and clinical results

OBJECTIVE: To analyse retrospectively from case notes and follow-up examinations the effectiveness of vascular surgery for renal artery aneurysm (RAA). PATIENTS AND METHODS: Operations for uni- or bilateral RAA were performed, between January 1978 and December 1996, on 61 patients (39 women, 22 men; mean age 47.4 years), 81% with arterial hypertension. Extracorporeal reconstruction with renal autotransplantation was performed in 4 of the patients. Clinical examination and duplex sonography or angiography were performed a mean of 58.4 months postoperatively. RESULTS: Postoperative morbidity rate related to the surgery was 13%; there were no early postoperative death. At the time of follow-up 80% of the reconstructed renal arteries were patent. 26% of hypertensive were cured of the hypertension, while the blood pressure was significantly reduced in 40%. CONCLUSIONS: Vascular reconstruction of RAA can be effective so that primary nephrectomy is no longer indicated. Reconstruction in situ can usually be successfully performed, reducing operative time and reducing surgical trauma. The operation is indicated in any RAA of greater than 2 cm diameter, in all patients with hypertension and renal artery stenosis, and also for smaller aneurysms in patients in good general health and in women of child-bearing age.     

Transcranial duplex sonography of middle cerebral artery stenosis: a comparison of colour-coding techniques--frequency- or power-based Doppler and contrast enhancement

The main limitation of transcranial colour-coded duplex sonography (TCCD) is the inadequate acoustic window, which prevents transtemporal identification of the basal cerebral arteries in up to 30% of cases, especially in the elderly. TCCD with different colour-coding techniques, including frequency-based colour-flow (CFD) or power (PD) Doppler sonography, used alone or in combination with contrast media, were used in 23 patients with middle cerebral artery (MCA) stenosis. In 10 patients a contrast medium (400 mg/ml SHU 508 A) was administered because of inadequate colour-coded visualisation with TCCD. The data were compared with angiographic methods. Digital subtraction angiography (DSA) revealed 2 low-grade, 11 middle-grade and 10 high-grade stenoses in the M1 segment. With TCCD, we found a 7.7% higher blood flow velocity (systolic peak velocity) than with transcranial duplex sonography without colour-coding because of visual angle correction and a 20% higher systolic peak velocity using contrast enhancement. CFD did not differ from PD in identification of low- and middle-grade MCA stenoses, but PD alone revealed two more cases of high-grade stenosis than CFD. The contrast medium increased diagnostic confidence in 8 of 10 cases. Only 2 of 23 MCA stenoses (9%) could not be shown using TCCD.     

Chronic carbon disulfide encephalopathy

To understand central nervous damage after long-term exposure to carbon disulfide (CS2), 10 patients who had polyneuropathy with various neuropsychiatric symptoms in a viscose rayon plant were studied. Clinical and laboratory examinations including electroencephalography (EEG), brain computed tomography (CT), brain magnetic resonance images (MRI), and carotid duplex sonography were carried out. Clinically, headache, unpleasant dreams, memory impairment, fatigue, anorexia and emotional lability were common in these patients while 2 patients had stroke episodes. EEGs were all normal. Brain CT scan showed mild cortical atrophy in 3 and low density lesions in the basal ganglia in 3. Brain MRI studies also disclosed mild cortical atrophy in 4 and multiple lesions involving the basal ganglia and corona radiata in 4. Carotid duplex sonography revealed mild atherosclerosis with plaques (< 20% stenosis) of extracranial vessels in 6. However there was no significant difference in flow velocities and flow volumes in the extracranial carotid arteries between patients and the normal controls. Interestingly, 2 patients had multiple brain lesions in the subcortical white matter but without strokes. In conclusion, encephalopathy with possible strokes may occur after chronic exposure to CS2, as well as polyneuropathy. The lesions usually involve the basal ganglia and subcortical white matter. Furthermore, MRI study may detect brain lesions particularly in the subcortical white matter areas before the occurrence of stroke.     

Renal artery angioplasty for renovascular hypertension and preservation of renal function: long-term angiographic and clinical follow-up

OBJECTIVE: Percutaneous transluminal angioplasty of stenoses of the renal artery can be used to treat hypertension and renal insufficiency. Although many studies have been published on the short-term results of this procedure, few long-term studies are available. SUBJECTS AND METHODS: One hundred ninety-five patients (123 men and 72 women 19-79 years old; mean age, 56 years) with stenosis of the renal artery and hypertension underwent renal percutaneous transluminal angioplasty at our institution. The stenosis was unilateral in 66% of patients, bilateral in 26%, and in a solitary functioning kidney in 8%. Renal insufficiency was present in 31% of patients. After renal percutaneous transluminal angioplasty, long-term clinical and angiographic follow-up was evaluated by life-table analysis. RESULTS: In patients with fibromuscular disease, blood pressure returned to normal in 57%, improved in 21%, and was unchanged in 21%. In patients with atherosclerotic stenosis, blood pressure returned to normal in 12%, improved in 51%, and was unchanged in 37%. After percutaneous transluminal angioplasty, renal function improved in 48% of patients with renal insufficiency due to bilateral stenosis or stenosis in the single functioning kidney, whereas none of the patients with unilateral stenosis of renal artery and renal insufficiency had any notable improvement. Long-term follow-up showed a high rate (82%) of patency of revascularized arteries and a low rate (21%) of hypertension recurrence at 5 years. CONCLUSION: Renal percutaneous transluminal angioplasty is useful for treating hypertension and for reestablishing renal function. Its effects on blood pressure and renal function are long-lasting in the large majority of patients.     

Porcelain veneer repair of prostheses

To investigate the relationship between age and renal vascular resistance and to establish normative data of the systolic/diastolic ratio (S/D ratio), pulsatility index (PI), and resistant index (RI) of the renal artery in the normal pediatric population, we studied 252 normal children aged newborn to 13 years (a total of 449 kidneys) with a color Doppler unit. After the normality of the kidney was established, color flow mapping was performed to localize the segmental portion of the renal artery. Flow velocity waveforms were then obtained by pulsed Doppler, and S/D ratio, PI, and RI were calculated. Multiple regression analysis confirmed the age dependence of the S/D ratio, PI, and RI of the renal artery in normal children. Renal vascular resistance continuously declines after birth and stabilizes at the age of 102-130 months. Normative data for S/D ratio, PI, and RI of the renal artery in normal children were established for each age group. Since renal vascular resistance decreases with age and stabilizes at 8-10 years, we suggest using different normal ranges for each age group when studying renal vascular resistance in pediatric patients.     

Pulsed Erbium:YAG laser ablation in cutaneous surgery

No non-invasive test can predict the clinical outcome of renal revascularization procedures. Because duplex sonographic measurements of intrarenal flow patterns reflect the resistance to flow within the kidney, the prognostic value of the cortical end-diastolic to peak systolic (d/s) velocity ratio was investigated in patients undergoing intervention for renal artery stenosis. The clinical and duplex sonographic data on 32 patients with 35 interventions (30 percutaneous transluminal angioplasties and five operations) on 42 renal artery sides were analysed. Twenty-three patients had atherosclerotic renal artery stenosis and nine patients had fibromuscular dysplasia resulting in > or = 60% renal artery stenosis. Measurements of the renal to aortic velocity ratio and cortical d/s ratio were performed before and after intervention. In the atherosclerotic patients, three interventions were clinically and technically successful, eight were technically successful but clinical failures, and 14 were clinically and technically unsuccessful. In the fibromuscular dysplasia patients, eight interventions were clinically and technically successful, and two were clinically and technically unsuccessful. The difference between the corresponding d/s ratios for atherosclerotic and fibromuscular dysplasia sides was significant on both the treated and not-treated sides (P < 0.02, two-tailed unpaired t-test). None of the 11 clinically successful procedures had a d/s ratio below 0.3, compared with seven values below 0.3 in the 24 clinically unsuccessful interventions (P = 0.05, one-tailed Fisher's exact test). It is concluded that: (1), a d/s ratio below 0.3 correlates with clinical failure in subsequent treatment of hypertension by renal revascularization, while a value above 0.3 has no prognostic significance; (2), despite technical success, not all atherosclerotic patients have clinical success from renal artery interventions; (3), in fibromuscular dysplasia patients, all clinical failures of renal artery interventions are associated with technical failures; and (4), the difference in d/s ratio between atherosclerotic and fibromuscular dysplasia patients may be a consequence of the more advanced age, longer duration of hypertension and additional risk factors in atherosclerotic patients.     

Doppler examination of cerebral arteries in uremic children

Transcranial Doppler ultrasonography is a useful method for the estimation and monitoring of cerebral circulation in dialyzed patients. The aim of this study was to evaluate the effect of disease and treatment on cerebral circulation in children on maintenance hemodialysis (HD) and children prior to renal replacement therapy. We demonstrated that in uremic children blood flow velocities of the internal carotid artery (ICA), anterior cerebral artery (ACA), middle cerebral artery (MCA), and posterior cerebral artery (PCA) 120 min and 240 min from the beginning of an HD session were significantly lower than values immediately before HD. Changes in blood flow velocities of MCA and ACA during HD correlated significantly with changes in mean arterial pressure during HD. There was no correlation between changes in blood flow velocities and intradialytic changes in hematocrit values, ultrafiltration, hemoglobin concentration, and blood urea nitrogen values. Mean blood flow velocities of ICA, MCA, and PCA in euvolemic children on conservative treatment were significantly higher than after a HD session in children on maintenance HD. The factors responsible for intradialytic velocity changes of cerebral arteries in uremic children require further examination.     

Intrarenal arterial Doppler sonography in the detection of renal vein thrombosis of the native kidney

OBJECTIVE: Previous studies of transplant kidneys and recent reports on native kidneys have suggested intrarenal arterial Doppler findings can be helpful in the noninvasive workup of renal vein thrombosis. We used arterial Doppler sonography to evaluate cases of possible acute renal vein thrombosis in native kidneys that had equivocal results on standard Doppler analysis of the renal vein. MATERIALS AND METHODS: Twenty native kidneys in 12 patients with clinical findings suggestive of acute renal vein thrombosis had Doppler studies of the main renal vein that failed to show normal flow. In all 20 kidneys, duplex Doppler study of arcuate/interlobar intrarenal arteries was done and the resistive index was determined. The Doppler findings were compared with subsequent findings on either renal venograms (n = 11) or MR images (n = 9), which served as the reference "gold" standards. RESULTS: The prevalence of renal vein thrombosis was 25% (5/20). Ten kidneys had very abnormal findings on arterial Doppler studies (absent or reversed end-diastolic flow), but only two of these were proved to have renal vein thrombosis. In six other kidneys, end-diastolic flow was identified but the resistive index was still elevated (> or = 0.70), and only one of these kidneys was proved to have renal vein thrombosis. Four kidneys had normal arterial Doppler studies, and 50% (two) of these were proved to have renal vein thrombosis. When absent or reversed end-diastolic flow was used as a sign of renal vein thrombosis, intrarenal arterial Doppler analysis had a sensitivity of 40% (2/5) and a specificity of 47% (7/15). CONCLUSION: Unlike the reported experience in transplanted kidneys, intrarenal arterial Doppler analysis is neither sensitive nor specific for renal vein thrombosis in native kidneys. An intrarenal arterial Doppler study with normal findings should not prevent further workup if Doppler findings in the renal vein are equivocal, nor should absent or reversed end-diastolic arterial signals be considered highly suggestive of renal vein thrombosis.     

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.     

The value of color-coded duplex ultrasound as standard assessment in erectile dysfunction

Erectile dysfunction has taken on increasing importance in urologic practice. Still open is the question of which tests are mandatory for adequate clinical assessment of erectile dysfunction. One accepted standard modality is the intracavernous pharmacotest with vasoactive agents. In contrast, color duplex sonography is not considered mandatory although it reveals detailed information about penile vessels and functional implications. The question remains whether the information gained by color duplex sonography is relevant for therapy, making it an indispensable standard procedure. Patients with erectile dysfunction were evaluated, without preselection, by extensive history, clinical evaluation, laboratory tests, tumescence and rigidity measurements, intracavernous administration of vasoactive drugs and color duplex sonography. Seventy-nine patients were available for final analysis. Color duplex sonography revealed 39 normal tests, 16 arterial impairments. 19 venous leakages and 5 arteriovenous fistulae. Intracavernous vasoactive agents (pharmacotest) revealed 44 reactions sufficient for intercourse and 35 insufficient responses. In 89% of patients, the diagnoses on color duplex sonography and intracavernous pharmaco-testing were similar. The accuracy of the two methods in diagnosing erectile dysfunction was not statistically different (McNemar's test). In contrast to intracavernous pharmaco-testing, color duplex sonography permitted further etiologic subdivision into arterial disease, venous leakage, arteriovenous fistula and normal result. This was made possible by measuring significantly (P < 0.01) different arterial peak flow velocities, end-diastolic velocities and calculated resistance index. These data did not imply direct clinical consequences. Color duplex sonography and intracavernous pharmacotesting reveal comparable results concerning the diagnosis of an erectile dysfunction. In contrast to pharmacotesting, color duplex sonography reveals details of the nature of the erectile dysfunction. Because this information has no profound implications for the choice of therapeutic procedure, color duplex sonography can not be recommended as a standard procedure in the evaluation of erectile dysfunction.     

The effects of an outpatient practice guideline at a teaching hospital: a prospective pilot study

BACKGROUND: Platelet-activating factor (PAF) is a bioactive phospholipid which is a potent hypotensive agent. To investigate the role of PAF in renovascular hypertension, we determined the PAF concentration and its production level assessed by the activity of cholinephosphotransferase (CPT) in renal tissue and examined the effect of a PAF antagonist on the mean arterial pressure (MAP) in control and two-kidney with one clipped (2K1C) hypertensive rats. MATERIALS AND METHODS: The concentration of PAF and CPT in the renal medulla and cortex were determined by radioassay. Also, the effect of a PAF antagonist, CV-6209, on MAP was also examined in both 2K1C hypertensive and normal control rats. RESULTS: The PAF concentration and CPT activity were significantly higher in the medulla than in the cortex in both 2K1C hypertensive and normal control rats, and both values in the medulla were also significantly higher in the clipped kidney than in the contralateral unclipped kidney or in control rat kidneys. We also observed a significant negative correlation between the PAF concentration in the medulla, and the medulla weight in the clipped kidney of 2K1C hypertensive rats. Infusion of the PAF antagonist, CV-6209, did not affect MAP in 2K1C hypertensive rats, but was significantly increased (P < 0.05) in control rats. CONCLUSIONS: These findings suggest that PAF, whose production is induced by renal ischemia due to renal artery stenosis, plays an important role in the renomedullary vasodepressor system, but the effect of PAF as a vasodilator in the peripheral vessels is limited in 2K1C hypertension.