Biomedical subjects
P Devos
Publications and source records attributed to P Devos.
Doppler flow wire evaluation of renal blood flow reserve in hypertensive patients with normal renal arteries.
PURPOSE: To study the vasomotor responses of the renal microcirculation in patients with essential hypertension. METHODS: We studied the reactivity of the renal microcirculation to papaverine, with intraarterial Doppler and quantitative arteriography, in 34 renal arteries of 19 hypertensive patients without significant renal artery stenosis. Isosorbide dinitrate was given to maximally dilate proximal renal arteries. APV (average peak blood flow velocity) was used as an index of renal blood flow. RESULTS: Kidneys could be divided into two distinct subgroups based on their response to papaverine. An increase in APV of up to 55% occurred in 21 kidneys, an increase > 55% in 13 kidneys. Within each group the values were normally distributed. Both baseline APV and the effect of papaverine on mean velocity differed significantly between groups. CONCLUSION: There seems to be a subgroup of patients with essential hypertension that has an impaired reactivity to papaverine, consistent with a functional impairment of the renal microcirculation. Further studies are required to determine whether this abnormality contributes to or results from elevated blood pressure.
Acute effect of ketanserin on the leg perfusion assessed by Doppler pressure measurements and 201Tl scintigraphy in patients with intermittent claudication.
Ketanserin, a serotonin2-receptor blocker, was administered intravenously (10 mg) to 10 patients suffering from unilateral intermittent claudication in a double-blind, placebo-controlled, cross-over design. The acute effect of the drug was studied by doppler systolic pressure (SP) measurements at arm and ankle at rest (10 min after injection) and after exercise, and by radioactive thallium (201Tl) stress scintigraphy of the legs. Resting ankle-arm SP ratio was significantly higher after ketanserin compared with placebo. This was due to a lowered systemic SP with unchanged ankle SP. This difference was not seen after exercise. In addition, the drug did not influence significantly the postexercise accumulation of thallium in the distal leg on the affected or healthy side, although the difference between these two became significantly larger in favour of the healthy leg. Thus, acute administration of ketanserin improves peripheral hemodynamics in claudicating patients at rest, but muscle exercise abolishes this response. A beneficial effect of ketanserin in intermittent claudication cannot be anticipated from these results.
[Angiotensin II receptor antagonists: different or equivalent?].
ARA-II: Angiotensin II receptor antagonists (ARA-II) belong to a recent class of antihypertensive drugs whose mechanism of action is similar to converting enzyme inhibitors (CEI). ARA-II are particularly interesting due to the excellent clinical and biological tolerance, similar to placebo, and their antihypertensive efficacy, comparable with classical drug classes. PUBLISHED TRIALS: A meta-analysis, published by Conlin in the American Journal of Hypertension, suggests that ARA-II, specifically losartan, valsartan, irbesartan and candesartan, have an equipotent blood pressure lowering effect. The careful lecture of this meta-analysis however discloses a faulty methodology from which no valid conclusion can be drawn. Since this early publication, several other comparative studies have been published. These multicentric, randomized double-blind studies enrolled a sufficient number of patients and demonstrated a clinical difference between certain ARA-II at usual dosages. CLINICAL PRACTICE: These studies do have an impact on everyday practice. For the practitioner, the goal is to obtain and then maintain a long-term and optimal reduction in the blood pressure level (reduction or prevention of target-organ disorders and cardiovascular complications of high blood pressure). This reduction in the cardiovascular risk will also depend directly on tolerance and compliance to the antihypertensive treatment. This element must also be considered in assessing treatment efficacy, independent of the blood pressure lowering effect. The results of several other studies will be published in 2001-2003. These large-scale studies on ARA-II related morbidity and mortality will be most useful in determining the role of these drugs in different therapeutic strategies compared with other drug classes.
[Clinical significant of serum chromogranin A levels for diagnosing pheochromocytoma in hypertensive patients].
OBJECTIVE: CMA is a widespread glycoprotein located in the secretory vesicles of neuroendocrine cells and is co-released with peptides and biogenic amines into the circulation. The present study set out to investigate the clinical utility of assessing serum CGA levels in comparison with the urinary KTCO and their urinary metabolites concentrations, which are to date the gold standard validated diagnostic test. METHODS: From January 2000 to June 2001, 202 consecutive patients, aged 53 +/- 12.7, 102 males, were admitted to our department for a hypertension evaluation. Blood samples for measurements of plasma concentrations of chromogranin A were collected and serum CGA levels were quantified by RIA technique (RIACT). This radioimmunometric technique consisted in using 2 monoclonal antibodies directed to 2 specific antigenic domains of the middle portion of the CGA. The fixed threshold value for identifying positive results was, set at 100 ng/ml according to previous studies. RESULTS: No pheochomocytoma was diagnosed by conventional urinary KTCO essay. Of the 202 CGA blood samples, 32 turned out to be positive, due to commonly encountered false positive causes (inhibitor of the pump with protons, corticotherapy, hypergastrinemia, chronic renal insufficiency, respectively, in 11, 2, 1, 18 cases). The CGA plasma concentration averaged 77 +/- 77 mg/ml and 203 +/- 125 ng/ml in the CGA subgroup over the threshold value. CONCLUSION: The reliability of immunoradiometric serum CGA concentrations appeared according to this work to be comparable to that of the urinary KTCO levels and their urinary metabolites in hypertensives. Moreover, it solely requires a simple, easily done blood taking, less expensive than urinary KTCO collection. Besides, no antihypertensive drugs interfered with the analysis of CGA levels. However, some false positive results have to be mentioned in the presence of renal impairment, hypergastrinemia, corticotherapy, inhibitor of the pump with protons.
[Clinic and morphologic evolution five years after a renal atherosclerotic artery stenosis (RAS): a study of twenty nine hypertensive patients population].
The indication of renal atherosclerotic artery stenosis revascularisation is always debated in clinical practices when arterial hypertension is stabilized by the treatment, especially if the stenosis is discovered fortuitously. The clinician needs clinical and morphological markers which will indicate or not the revascularisation in the situation of "nephronic protection". The benefits of angioplasty have been studied on the blood pressure, the creatinine clearance, the glomerular function analyzed by scintigraphy, the renal length and more recently on the mean cortical thickness (MCT). The follow-up of these studies is generally inferior to 2 years. In this work, we tried to estimate the clinic and morphologic evolution 5 years after a unilateral artery stenosis angioplasty. From a group of 249 patients who had a renal angioplasty between January 1995 and January 2000 (T0), 29 patients with refractory hypertension and with a unilateral atherosclerotic renal artery stenosis on spiral computed tomographic angiography (TCA) performed at T0 [17 M; 12 W; medium age 68.6 +/- 10 years] were included. The TCA performed at 5 years (T5) eliminated a new renal arterial stenosis or restenosis. We have analyzed 29 revascularized kidneys (kidney S) and 29 controlateral kidneys (kidney C), the blood pressure and renal function. The renal length (mm) was at T0: kidney C=99.4 +/- 13.5; kidney S=93.5 +/- 10.8 and at T5: kidney C=99.4 +/- 12.6; kidney S=94.2 +/- 10.7. MCT (mm) was at T0: kidney C=7 +/- 1.2; kidney S=6.6 +/- 1.1 and at T5: kidney C=6.2 +/- 1.2; kidney S5=6 +/- 1. The cortical atrophy got worse while the renal length and creatinine clearance were stable: only diastolic blood pressure was controlled (78.8 mmHg +/- 11.9). In spite of small strength, this study arguments the fact that the angioplasty isn't sufficient to control the arterial hypertension in an atheromatous context, not allowing to slow the evolution of distal cortical lesions with however a stability of creatinine clearance.
[Usefulness of magnetic resonance angiography in the screening of renal artery stenosis in hypertensive patients: proposition of a diagnostic algorithm: a study of 245 patients].
Usefulness of magnetic resonance angiography in the screening of renal artery stenosis in hypertensive patients: proposition of a diagnostic algorithm: a study on 245 patients. Different non-invasive techniques, including Duplex, spiral angioscan, and magnetic resonance angiography (MRA) are available for the diagnosis of renal artery stenosis (RAS). The aim of this study was to assess the diagnostic performances of MRA and the MRA-Duplex couple in the diagnosis of RAS. Between September 2003 and January 2005, 245 patients benefited from a renal MRA for the assessment of hypertension etiology. The MRA-Duplex couple was performed in 228 patients. Renal arteriography was performed in case of abnormalities observed with MRA and/or Duplex (n=41). The sensitivity and specificity of MRA were respectively at 100% and 23%. The sensitivity was notably higher in the right renal artery (100 vs. 73%). The sensitivity and specificity of Duplex were respectively at 71 and 85%. The concordance between the two exams was disappointing (kappa at 0.39 for the right side and 0.62 for the left side), leading to the interest of the MRA-Duplex association for excluding the presence of RAS (sensitivity and negative predictive value=100%). However, using the MRA-Duplex couple led to a high number of false positive cases, due to MRA, leading to 11 angiograms out of 41 exams, without any significant RAS. In case of suspicion of RAS, the MRA-Duplex couple permits to exclude definitely the diagnosis of RAS. In case of discordance between the 2 exams, it would be useful to require a spiral angioscan and/or redo a Duplex exam using contrast agents, prior to angiography with a therapeutic goal. These management modalities might be useful to avoid the number of normal angiograms, with an inherent risk of complications and cost excess.
Value of indium-111-labeled leukocytes scintigraphy in patients after arterial reconstructive surgery.
The study was performed to evaluate the diagnostic value of Indium-111-leukocytes scintigraphy in arterial prosthetic infection. Scintigrams were performed in 19 patients in two groups. Group A consisted of 11 patients, where ten days after uncomplicated graft implantation, an Indium-111-scintigraphy was performed. Group B consisted of 8 patients, where we suspected an infected arterial graft. In group A we had one false-positive scan and in group B one false-negative scan. This gives an accuracy of 89%, a sensitivity of 87% and a specificity of 90%. These results indicate that Indium-111-leukocytes scintigraphy is a favourable test to detect a vascular graft infection.
Critical appraisal of angioscintigraphy as a diagnostic procedure in cerebrovascular disease.
In order to assess the diagnostic usefulness of combined functional and morphological isotopic investigations of brain vascularization after intravenous injection of a bolus 99mTc pertechnetate, the authors explored, besides a control group, patients with acute cerebrovascular disease, angiomas, aneurysms and intracerebral hematomas. Combined flow evaluation and visualization of the intracerebral bolus transit was highly effective in patients with cerebrovascular disease. Angiomas with a diameter of 2 cm or more are always visible, the abnormal vascularization of the affected hemisphere being correctly evaluated. Cerebral aneurysms are frequently missed by angioscintigraphy. Intracerebral hematoma generally gives false negative results.