PubMed Health⌕ Search

Biomedical subjects

H Valette

Publications and source records attributed to H Valette.

At least 19 recordsLinked to original sources
PubMed1992

Myocardial perfusion damage after mediastinal irradiation for Hodgkin's disease: a thallium-201 single photon emission tomography study.

Conflicting data have been reported on the incidence of myocardial abnormalities after mediastinal irradiation for Hodgkin's disease. We studied myocardial perfusion in 31 clinically asymptomatic patients (13 male, 18 female, mean age 35 years) 7 years (range 3-11 years) after mantle field radiotherapy. Thallium-201 tomoscintigraphic data were obtained after exercise, 4 h later and at rest (8-15 days later). Images were analysed visually and quantitatively (sectorial quantification of 201Tl uptake on the bull's eye images of the short-axis slices) compared with those of 35 subjects with a low likelihood of coronary artery disease. Twenty-five tomographic data sets were available. Images were visually abnormal in 21 patients (84%) showing an heterogeneous 201Tl uptake. In 68%, the sectorial 201Tl uptake was lower than the mean 201Tl uptake value minus 2 standard deviations measured in subjects with a low likelihood of coronary artery disease. Significant redistribution (quantitatively assessed > or = 10%) was present in 10 patients (40%). In most of the patients, the location and the shape of the defect(s) could not be anatomically related to an epicardial coronary vessel disease. These results indicate that after mediastinal irradiation the 201Tl myocardial uptake is frequently abnormal. The observed patterns suggest a disease of the small coronary vessels and/or the existence of a myocardial fibrosis rather than epicardial coronary artery disease.

Adult↗
PubMed1992

Myocardial beta-adrenergic desensitization and neuronal norepinephrine uptake function in idiopathic dilated cardiomyopathy.

Desensitization of myocardial beta-adrenergic receptors may result both from an impairment of the norepinephrine (NE) neuronal uptake function and from an increase in circulating NE concentrations. The respective role of these two mechanisms of desensitization was examined in 18 patients with congestive heart failure related to an idiopathic dilated cardiomyopathy. The neuronal NE uptake system was evaluated by [123I]metaiodobenzylguanidine (MIBG) scintigraphy. The desensitization level of beta-adrenoceptors was assessed as the net increase in peak positive left ventricular (LV) dP/dt during intracoronary dobutamine infusion. Arterial NE concentrations were determined at baseline. To obtain control values, we performed MIBG scintigraphy and determined baseline NE concentration in 12 normal subjects. Cardiac MIBG uptake was significantly decreased in patients as compared with controls. This decrease was related to the severity of the disease based on hemodynamic indexes. The inotropic response to intracoronary dobutamine infusion of heart failure patients correlated with both increased baseline NE concentration and diminished cardiac MIBG uptake (r = -0.63, p less than 0.01 and r = 0.73, p less than 0.001, respectively). These findings indicate that the desensitization process is related both to impaired neuronal NE uptake function and increased circulating NE concentrations. Moreover, a subset of 11 patients with moderate heart failure was identified who had diminished cardiac MIBG uptake but normal circulating NE concentrations. This suggests that impairment of the NE uptake function is an early mechanism of desensitization in idiopathic cardiomyopathy. Cardiac MIBG imaging may be a noninvasive means to assess severity of heart failure patients and may also be used to evaluate therapy effects on myocardial alterations of the adrenergic pathway.

3-Iodobenzylguanidine↗
PubMed1992

The value of pixel per pixel multiharmonic Fourier analysis to assess left ventricular function.

Left ventricular systolic and diastolic function can be assessed by peak ejection and filling rates and their time of occurrence. These parameters can be calculated using two different methods: from the global left ventricular time-activity curve analysed with a four harmonic Fourier fit and from each pixel time-activity curve analysed with two and three harmonics (the values being averaged over the left ventricular region of interest). In both cases, values were normalized for heart rate and end diastolic counts. A study was conducted in a series of 11 patients (six without and five with a previous myocardial infarction but a normal left ventricular function) examined at baseline and during an i.v. dobutamine infusion, at a dose known to increase both peak ejection and filling rates. During dobutamine infusion, analysis of global left ventricular time-activity curve demonstrated a statistically significant increase in both peak ejection and filling rates, but the local analysis showed a more significant increase of these parameters. To assess ventricular function, a local harmonic analysis can be used and appears to be a more sensitive approach than analysis of the global left ventricular time-activity curve. The local analysis provides spatial mapping and a histogram of the parameters which can be used as parametric images to describe systolic and diastolic function.

Dobutamine↗
PubMed1992

Prognostic value of cardiac metaiodobenzylguanidine imaging in patients with heart failure.

The prognostic value of 123I-metaiodobenzylguanidine (MIBG) imaging was compared with that of other noninvasive cardiac imaging indices in ninety patients (mean age = 52 +/- 7 yr) suffering from either ischemic (n = 24) or idiopathic (n = 66) cardiomyopathy. Patients had different measurements taken: cardiac MIBG uptake, radionuclide left ventricular ejection fraction, x-ray cardiothoracic ratio and echographic M-Mode data. Cardiac MIBG uptake was assessed as the heart-to-mediastinum activity ratio measured on the chest anterior view image obtained 4 hr after intravenous injection. The patients then had follow-up for 1-27 mo, at which time 10 patients had transplants, 22 had died and 58 were still alive. Data from patients with transplants were not used in the analysis, in which multivariate stepwise regression discriminant analysis showed that cardiac MIBG uptake was more potent to predict survival than other indices: H/M (p less than 0.0001), x-ray cardiothoracic ratio (p = 0.0017), echographic end-diastolic diameter (p = 0.0264) and radionuclide left ventricular ejection fraction (p = 0.0301). Moreover, multivariate life table analysis showed that cardiac MIBG uptake was also the best predictor for life duration: H/M (p = 0.0001), radionuclide left ventricular ejection fraction (p = 0.0098) and x-ray cardiothoracic ratio (p = 0.0139); echographic data were not useful. Thus, cardiac MIBG imaging may be helpful for heart transplantation decision making in patients with heart failure.

3-Iodobenzylguanidine↗
PubMed1991

Ventricular function during the acute rejection of heterotopic transplanted heart: gated blood-pool studies.

Twenty patients who had undergone a heterotopic heart transplant were studied prospectively to determine the relationship between rejection and ventricular dysfunction assessed from gated blood-pool studies. A fully automated method for detecting ventricular edges was implemented; its success rate for the grafted left and right ventricles was 94% and 77%, respectively. The parameters, peak ejection and filling rates, were calculated pixel per pixel using a two-harmonic Fourier algorithm and then averaged over the ventricular region of interest. Peak filling and ejection rates were closely related with the severity of the rejection, while the left ventricular ejection fraction was not. Peak filling rates of both ventricles were the indices closely related to the presence of moderate rejection. Despite the low number of patients, these data suggested that gated blood-pool-derived indices of ventricular function are associated with ventricular dysfunction resulting from myocarditis rejection. Radionuclide ventriculography provides parametric data which are accurate and reliable for the diagnosis of rejection.

Algorithms↗
PubMed1991

[Transitory acute kidney insufficiency and insulin-dependent after treatment of kala-azar with pentamidine and N-methylglucamine antimony].

Azotemia and diabetes mellitus are now well-known adverse reactions associated with Pentamidine treatment, especially since its prescription in case of Pneumocystis carinii pneumonia. We report the case of a 2 year-old boy, treated for kala-azar with pentamidine and N-methyl glucamine antimoniate who developed adverse effects, characterized by a nephrotic syndrome associated with the classic acute tubular necrosis, and transient diabetes mellitus.

Acute Kidney Injury↗
PubMed1990

[The role of isotope methods in evaluating the left ventricular function].

Cardiac angioscintigraphy is a non-invasive, reproducible and reliable technique used to obtain a number of cardiac function parameters, the most important of which is left ventricular ejection fraction. Methodologically, the examination is simple. Fourier's analysis (a mathematical decomposition of ventricular mechanics) provides additional information on some abnormalities and is particularly useful in segmental kinetics studies and in the topographical diagnosis of cardiac rhythm disorders. The technique is indicated mainly for prognostic evaluation and follow-up of patients with left ventricular dysfunction. Metaiodobenzylguanidine (MIBG) cardiac scintigraphy makes it possible to evaluate the reuptake of noradrenaline by neurons, which represents the inactivation pathway of adrenergic neurotransmission and is the principal factor of noradrenaline extraction. MIBG scintigraphy is an indirect way of evaluating left ventricular function in congestive heart failure, as suggested by the results of studies showing correlations between MIBG uptake, left ventricular function indices and disease severity as judged on the basis of evolutive parameters.

3-Iodobenzylguanidine↗
PubMed1990

Filters and Fourier analysis of gated blood pool studies: a search for the optimal combination.

Fourier analysis of gated blood pool studies is performed after filtering the raw data by a spatial median 3 x 3, 9 x 9 or temporo-spatial 9 x 9 x 9 filter. 20 patients and a dynamic cardiac phantom were studied to determine the quantitative effects of these filters and of multiharmonic Fourier filtering (MHFF). The filtered MHFF data, with or without preprocessing, were compared with a 3 D or 2 D filter to the raw data using a chi 2 distribution. The MHFF (two or three harmonics) procedure applied to the raw data of patients without any preprocessing produced the smallest chi 2 value, thus demonstrating the very close relationship between filtered images and raw data. Preprocessing the raw data by the median filter also preserved the signal when two or three harmonics were applied, whereas the 3 D and 2 D (9 x 9) filters did not. The phantom study also demonstrated that MHFF preserved the signal better than any other preprocessing. The median filter introduced a smaller distortion than the 2 D (9 x 9) and 3 D filters. It is concluded that MHFF applied with two or three harmonics on the raw data or after preprocessing by a median (3 x 3) filter is the most successful way of preserving the real signal. It is believed that the other filters should be avoided. The clinical advantage of MHFF processing is to provide both very accurate filtering and parametric images.

Fourier Analysis↗
PubMed1988

Automatic drawing of the left epicardial region of interest on thallium 201 scintigraphic images.

An algorithm has been written which automatically selects a left epicardial region of interest on 201Tl myocardial images. It accomplishes a radial search from the geometric center of the myocardium. On each of the 30 profiles, the local maximum of the 1st derivative is selected as the epicardial edge. The algorithm has been tested in 40 patients at stress and redistribution. In ten patients, conventional planar images were obtained in three views. In 30 patients conventional short axis tomographic images were obtained after reconstruction of 32 projections acquired over 180 degrees. The rate of success is 97% for both imaging modalities. This procedure is another step towards fully automated assessment of myocardial defects and redistribution.

Algorithms↗
PubMed1988

ECG gated thallium 201 myocardial images: value in detecting multivessel disease in patients on anti anginal therapy 1-3 months after myocardial infarction.

ECG gated 201Tl scintigraphy was compared to non gated images for detecting 2-3 vessel disease 1-3 months after a first uncomplicated myocardial infarction. In all, 111 patients on anti anginal treatment underwent coronary arteriography and stress thallium imaging; 39 showed single vessel disease (SVD), and 72 multivessel disease (MVD). Sensitivity of black and white analog images was 82% for SVD and 8% for MVD. Sensitivity of computerized colored static images was 87% for SVD and 33% for MVD. For gated images, sensitivity was 100% and 92% in patients with SVD and MVD respectively. Specificity for detecting MVD was 95% for black and white images, 77% for computerized colored static images, and 69% for ECG gated images. Thus, ECG gated exercise 201TL scintigraphy is useful for predicting the extent of coronary artery disease 1-3 months after myocardial infarction in patients on anti anginal therapy.

Angina Pectoris↗
PubMed1988

Accuracy of gated equilibrium radioventriculography in measuring left ventricular function in dogs.

To assess the precision of gated equilibrium radioventriculography in measuring changes in left ventricular stroke volume (LVSV), we studied five dogs each with a chronically implanted electromagnetic flowmeter on the ascending aorta. Per cent changes in left ventricular stroke counts (LVSC) were compared to those in LVSV following acute changes induced by positive end respiratory pressure. We have compared LVSCs calculated in five different ways: (1) Manual outlining of LV region of interest (LVROI), either single fixed enddiastolic (ED) ROI or ED and endsystolic (ES) ROIs with the aid of functional images (first harmonic of Fourier analysis); (2-5) automatic outlining of LV ROI (the algorithm generated 30 profiles on which the maximum of second derivative delineated the LV edges) was performed either on ED image or both ED and ES images. For these four methods a crescent-shaped ROI for background correction was manually drawn at the border of the LV ROI. The fifth method used an automatically drawn single fixed LVED ROI with interpolative background substraction (IBS) between LV and RV edges. LVSC changes, calculated with the IBS method correlated better with LVSV changes than the other four methods. Thus assessment of small LVSC changes is highly processing-dependent.

Animals↗
PubMed1988

[Mullerian adenosarcoma of the uterus. Review of the literature. Apropos of a case].

The authors report a case of müllerian adenosarcoma in an 86 year old woman. This tumor is characterized by the association of proliferative benign epithelium with a sarcomatous mesenchyma. It was described for the first time in 1974 by Clement and Scully. It is a cancer of decreased malignancy, revealed either by isolated metrorrhagias, or by an increase of the size of the uterus in a post-menopausal woman. Its course shows the occurrence of local recurrences and pulmonary or peritoneal metastases. The only appropriate treatment is total abdominal hysterectomy with salpingo-oophorectomy.

Aged↗