Search PubMed⌕ Search

Biomedical subjects

H Valette

Publications and source records attributed to H Valette.

At least 55 records · Page 3Linked to original sources
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

Non-invasive measurement of pulmonary arterial pressure: I. A haemodynamic modelling approach.

In order to monitor pulmonary arterial pressure (P) by any non-invasive imaging technique, a haemodynamic model of blood flow kinetics and wall mechanics has been developed. It is a one-dimensional model of pulsatile flow in an elastic pulmonary arterial trunk, assuming that blood is an incompressible fluid and viscous effects are negligible. The equations are P(t)-Pd = rho c2lnS(t)/Sd-1/2pw-2(t) Pd = (Sd/Ss)1/2Pp where, at any time of the ejection phase of systole, P(t), S(t) and w(t) are the pulmonary arterial pressure, cross-sectional area of the pulmonary artery and blood velocity averaged on the cross section S, respectively, PP is the pulse pressure, the difference between the peak systolic pressure and the diastolic pressure Pd; rho is blood density, c pulse wave velocity, and Ss and Sd are maximum (systolic) and minimum (diastolic) values of the cross-sectional area S. Using these equations, P(t) can be calculated if the three parameters, i.e. c, S(t) and w(t) are measured. So far, it has been impossible to measure the pulse wave velocity c non-invasively. We have investigated the calculation of c from S(t) and w(t) using the equation of continuity in the absence and presence of reflected pressure waves. The hypotheses of the haemodynamic model are discussed.

Blood Flow Velocity↗
PubMed1988

Non-invasive measurement of pulmonary arterial pressure: II. A radionuclide method.

Pulmonary artery pulse pressure (PP) and diastolic pressure (Pd) may be obtained by applying a haemodynamic model of blood flow kinetics and wall mechanics to the pulmonary artery: Pp = rho(ws/(Ss/Sd-1))2log(Ss/Sd)-1/2 rho w2s Pd = (Sd/Ss)1/2Pp where rho is blood density, ws is peak ejection velocity, and Ss and Sd are peak maximal and end diastolic cross-sectional areas of the main pulmonary artery. The different parameters of the equations were measured from radionuclide first pass and equilibrium studies. Radionuclide first pass studies were performed in 24 patients with intravenous injection of 20 mCi of 99Tcm red blood cells with a gamma camera in a 20 degrees right anterior oblique position: data were collected in list mode, i.e. a continuous sequence of spatial and temporal coordinates of each photon. Pulmonary arterial pressure was recorded simultaneously with a microtip catheter during the first pass study. Gated first pass images of the right side of the heart were reconstructed, regions of interest drawn over the right ventricle and the main pulmonary artery (MPA) and time-activity curves generated. Peak systolic (Cs) and end diastolic (Cd) counts obtained from the MPA curve were proportional to the cross sections Ss and Sd of the MPA and Ss/Sd = Cs/Cd. The diameter (D) of the pulmonary artery was calculated as the distance between the two zeros of the second derivative of a cross-sectional profile. The averaged cross-sectional area was S = pi D2/4. ECG gated blood pool studies were performed in a LAO 40 degrees position when the tracer was at equilibrium; they were processed automatically and the right ventricular end diastolic counts (EDC) converted into volume (EDV) using an aortic volume/count ratio. Right ventricular peak ejection rate (PER) was obtained from the RV time-activity curve and the instantaneous peak ejection velocity was calculated, ws = PER X EDV/S X EDC. PP and Pd were calculated in mmHg and the radionuclide method yielded pressure values that correlated reasonably with catheterisation values: PP(rad) = 0.99 PP(cath)-0.55, r = 0.84 and Pd(rad) = 0.67 Pd(cath) + 4.91, r = 0.74. We conclude that radionuclide techniques can provide a non-invasive method based on a haemodynamic model for measuring pulmonary arterial pressure.

Adult↗
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↗
PubMed1987

Evaluation of 3 dimensional space and time filtering on ECG gated 201Tl myocardial images.

Stress 201Tl myocardial images were obtained using a standard ECG gated acquisition protocol for 10 min per view. These images were filtered using a three dimensional space and time filter. The effects of filtering were evaluated by sectorial analysis. Comparing raw and filtered dynamic images, quantification demonstrated that filtering did not produce artefacts. A conventional static image was also obtained as the sum of the series of unfiltered dynamic images. Comparison of raw static and filtered diastolic images indicated that the latter demonstrated myocardial abnormalities more clearly (P less than 0.01) in 33 patients. Improvement in the signal to noise ratio produced by filtering made cinematic display and visual analysis possible which was not feasible with raw gated images. Clinical evaluation is in progress.

Diastole↗
PubMed1987

Phase mapping of radionuclide gated biventriculograms in patients with sustained ventricular tachycardia or Wolff-Parkinson-White syndrome.

Accuracy of Fourier phase mapping of radionuclide gated biventriculograms in detecting the origin of abnormal ventricular activation was studied during ventricular tachycardia or preexcitation. Group I included six patients suffering from clinical recurrent VT; 3 gated blood pool studies were acquired for each patient: during sinus rhythm, right ventricular pacing, and induced sustained VT-Group II included seven patients with Wolff-Parkinson-White syndrome and recurrent paroxysmal tachycardia; 3 gated blood pool studies were acquired for each patient: during sinus rhythm, right atrial pacing and orthodromic reciprocating tachycardia. Each acquisition lasted 5 min, in 30 degrees-40 degrees left anterior oblique projection. In Group I, the Fourier phase mapping was consistent with QRS morphology and axis during VT (5/6), except in one patient with LV aneurysm and LBBB electrical pattern during VT. Origin of VT on phase mapping was located in the right ventricle (n = 2) or in left ventricle (n = 4), at the border of wall motion abnormalities each time they existed (5/6). In Group II, the phase advance correlated with the location of the accessory pathway determined by ECG and endocardial mapping (n = 6) and per-operative epicardial mapping (n = 1). Discrimination between anterior and posterior localisation of paraseptal pathways and location of intermittent preexcitation was not possible. We conclude that Fourier phase mapping is an accurate method for locating the origin of VT and determining its etiology. It can help locate the site of ventricular preexcitation in patients with only one accessory pathway; its accuracy in locating multiple accessory pathways remains unknown.

Adult↗
PubMed1987

Automated processing of first-pass radionuclide angiocardiography by factor analysis of dynamic structures.

A method for automatic processing of cardiac first-pass radionuclide study is presented. This technique, factor analysis of dynamic structures (FADS) provides an automatic separation of anatomical structures according to their different temporal behaviour, even if they are superimposed. FADS has been applied to 76 studies. A description of factor patterns obtained in various pathological categories is presented. FADS provides easy diagnosis of shunts and tricuspid insufficiency. Quantitative information derived from the factors (cardiac output and mean transit time) were compared to those obtained by the region of interest method. Using FADS, a higher correlation with cardiac catheterization was found for cardiac output calculation. Thus compared to the ROI method, FADS presents obvious advantages: a good separation of overlapping cardiac chambers is obtained; this operator independant method provides more objective and reproducible results. A number of parameters of the cardio-pulmonary function can be assessed by first-pass radionuclide angiocardiography (RNA) [1,2]. Usually, they are calculated using time-activity curves (TAC) from regions of interest (ROI) drawn on the cardiac chambers and the lungs. This method has two main drawbacks: (1) the lack of inter and intra-observers reproducibility; (2) the problem of crosstalk which affects the evaluation of the cardio-pulmonary performance. The crosstalk on planar imaging is due to anatomical superimposition of the cardiac chambers and lungs. The activity measured in any ROI is the sum of the activity in several organs and 'decontamination' of the TAC cannot easily be performed using the ROI method [3]. Factor analysis of dynamic structures (FADS) [4,5] can solve the two problems mentioned above. It provides an automatic separation of anatomical structures according to their different temporal behaviour, even if they are superimposed. The resulting factors are estimates of the time evolution of the activity in each structure (underlying physiological components), and the associated factor images are estimates of the spatial distribution of each factor. The aim of this study was to assess the reliability of FADS in first pass RNA and compare the results to those obtained by the ROI method which is generally considered as the routine procedure.

Angiocardiography↗
PubMed1985

[Hypertrophic myocardiopathy with isolated obstruction of the right ventricle].

The authors report one case of biventricular hypertrophic cardiomyopathy in a 23 year old female patient with severe localized obstruction of the right ventricle (105 mm Hg gradient, almost complete angiographic disappearance of the middle and apical portions of the right ventricle during systole). Echocardiography, hemodynamic findings, and angiography demonstrated nonobstructive involvement of the left ventricle. Among other family members, only her father was noted to have minimal hypertrophic cardiomyopathy. A favorable response to therapy was obtained over 14 months with 320 mg of propranolol given daily (disappearance of palpitations and ventricular tachycardia which had previously been noted on a continuous 24 hour recording before treatment). Other very rare similar cases in the literature are analyzed. It is not possible to distinguish these cases from those with predominantly left ventricular involvement by clinical and radiological findings alone. However, the ECG can often demonstrate right ventricular involvement (right ventricular hypertrophy and/or right bundle branch block). Lastly, it appears that biventricular hypertrophic cardiomyopathies in young patients can initially be localized to only the right ventricle.

Adult↗
PubMed1984

[Association of lobular epithelioma and hypophyseal adenoma in a young woman. A case report].

The authors report the case of a 28 year old patient with a prolactin and somatotropin secreting pituitary adenoma who presented several months later with lobular carcinoma of the breast with lymph node metastases. This case raises the question of the role of prolactin and growth hormone in the pathogenesis and growth of breast cancer. It is noteworthy, in particular, because of the exceptional clinical manifestations.

Adenoma↗