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J Chambron

Publications and source records attributed to J Chambron.

At least 73 records · Page 4Linked to original sources
PubMed1986

[The contribution of magnetic resonance imaging in congenital heart diseases].

The diagnostic value of magnetic resonance imaging (MRI) was assessed in 30 patients with congenital heart disease, including 7 patients with postoperative sequellae. The images obtained by synchronizing the MRI spectrometer with the electrocardiogramme were recorded in 2 or 3 different planes (sagittal, frontal and transverse) and compared to clinical, angiographic and/or echocardiographic data. The MRI provided high resolution tomographic images enabling spatial reconstitution of the heart by the use of different planes. These images were particularly useful for showing the position and dimensions of the ventricles (both chamber size and wall thickness) and their relationship to the atria and great vessels. These results confirm the value of this new non-invasive imaging technique in the diagnosis of congenital heart disease, not counting the additional information on blood flow and tissue characterisation that will soon become available.

Heart Defects, Congenital↗
PubMed1986

[Nuclear magnetic resonance. Our preliminary experience on the normal heart and in various cardiopathies].

Nuclear magnetic resonance imaging (NMRI) is applied in our department to the study of the normal heart and in aortic, pericardial and myocardial pathologies: aortic aneurysms, hypertrophic cardiomyopathies, myocardial infarction, pericarditis and congenital cardiopathies. The apparatus used consists of a resistive magnet which provides a field of 0.15 Tesla. Synchronisation with the electrocardiogram leads to improvement of the cardiac signals. The documents obtained are promising to the extent that information concerning cardiac structure is provided in three planes (frontal, sagittal and horizontal) and is complementary to that provided by echocardiography, isotopic techniques and contrast angiography. The future potential of the method is considerable, particularly in the area of tissue characterisation.

Aorta↗
PubMed1985

NMR compartmentalization of free water in the perfused rat heart.

Spin-lattice (T1) and spin-spin (T2) relaxation times have been measured on perfused rat hearts under two experimental conditions. T1 exhibits a monoexponential decay. On the other hand T2 has a decay with two components: a short one T2s and a long one T2l. These facts have been discussed according to cross-relaxation and a bicompartmentalization of tissue assuming a slow exchange model for spin-spin relaxation and a fast exchange model for spin-lattice relaxation. Increasing the osmotic pressure of the perfusion solution decreased the absolute density proton of the T2s compartment reflecting the loss of its water content. The paramagnetic ion manganese diminishes the values of T1 and those of the long component T2l without affecting its short component. Therefore the short component could be assigned to intracellular and the long component to extracellular free water. The extracellular T2 (459 ms) is approximatively 10-fold higher than the intracellular T2 (45 ms). With images of "pure T2" such a difference could be useful to enhance the contrast between organs and the surrounding liquid or between organs with different water compartmentalization.

Animals↗
PubMed1985

[Clinical value of thallium-201 myocardial scintigraphy with dipyridamole performed before and after aortocoronary bypass].

In addition to preoperative coronary angiography, 63 patients undergoing coronary bypass surgery also had myocardial scintigraphy with dipyridamole 1 to 2 days before surgery, resting scintigraphy 10 after bypass and a repeat scintigraphy with dipyridamole 3 to 6 months later. The myocardium was divided into 5 segments. In each segment the perfusion was classified as: normal, presence of a reversible defect (redistribution), presence of a permanent defect (no redistribution). A comparison of pre-and postoperative scintigraphies led to the following conclusions. Three to six months after bypass, improved perfusion was observed in 65.6% os ischaemic segments, showing that surgery was very effective. On the other hand, the immediate postoperative control (10 days) only showed improved perfusion in 42.5% of the ischaemic segments: this interval was too short to appreciate the benefits of coronary bypass. There was a good correlation between the scintigraphic improvement after surgery and the reversibility of the zones of hypofixation of Thallium before surgery. When the defect was reversible, 80% of the revascularised segments were improved. Fifty-eight per cent of non-reversible defects before surgery were unchanged by the revascularisation procedure. However, the absence of redistribution during preoperative scintigraphy was not synonymous with definitive myocardial lesions and does not represent a contra-indication to coronary bypass surgery; in fact, improved perfusion was observed in 42% of these constant defects. The quality of recovery depends on the condition of the muscle: only segments with normal motion can be improved. Degradation of the clinical condition of patients was always related to aggravation(lack of improvement in 1 case) of scintigraphy.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Artery Bypass↗
PubMed1985

[Contribution to proton nuclear magnetic resonance imaging in multiple sclerosis. Contribution of a multiple spin echo sequence].

Single or multiple parenchymatous anomalies were detected in 48 of 49 patients with multiple sclerosis by proton magnetic resonance imaging (MRI) combined with a spin-echo sequence in the 4 planes of the section passing through the ventricular bodies. Lesions were identified in the frontal, orbital and particularly juxta-ventricular white substance, and were of variable appearance, the most common being spots in the parenchyma and juxta-ventricular bands. A limited number of sections is sufficient for the MRI study of anomalies in clinically defined multiple sclerosis, the diagnostic value of this examination suggested by these findings requiring confirmation by prospective studies.

Adolescent↗
PubMed1984

[The spatial vectorcardiogram loop. Estimation of its planarity by the calculation of a distortion coefficient. Trial of clinical evaluation].

Automatic techniques for interpreting the electrical activity of the heart are based more and more on vectorcardiographic parameters, especially information provided by the spatial vectorcardiographic loop. This data has been shown to be a useful complement to classical electrocardiography. The aim of this study was to define a method of calculation of the planes of the vectorcardiographic loops of depolarisation and repolarisation, and to calculate a coefficient of left-sidedness obtained by the sum of squares of the distances between the points on the loop in the plane. This value is then normalised with respect to the size of the loop. Normal values of this coefficient were first defined in a healthy reference population of 70 subjects: the values are expressed in (MV/10)2 or in mm2, and are 0,28 +/- 0,05 for the QRS and 0,0026 +/- 0,0008 for the ST-T. The coefficient was then calculated in different pathological groups, the diagnosis of which had been formally confirmed: ventricular hypertrophy, valvular heart disease, conduction defects, coronary artery disease. The highest values (four times normal) were obtained in right ventricular hypertrophy, right bundle branch block and infarction associated with conduction defects. The discriminative value of the coefficient of left-sidedness is discussed with the aim of distinguishing the normal from the pathological.

Adult↗
PubMed1984

[Evaluation of left ventricular function and regional kinetics following myocardial infarction. Comparative study of angiocardiography, echography and radionuclide angiography].

Left ventricular function and regional wall motion were studied three weeks after a myocardial infarction in 25 patients who had undergone L.V. monoplane cineangiography. The patients were studied by echocardiography (TM and 2D) and radionuclide angiography. Evaluation of global ejection fraction provides evidence of a close correlation between left ventricular angiography and radionuclide examination (r= 0.79). Measurement of ejection fraction by echocardiography (TM) remains clearly correlated with the same evaluation by angiography (r = 0.68). The correlations are markedly increased in the patients without significant wall motion defects (r = 0.87 for radionuclide angiography and r = 0.82 for echographic measurement). Sensitivity in the detection of L.V. aneurysms is excellent with our method of radionuclide examination (12/13) and can be compared with angiography (12/13). Two-dimensional echocardiography performed on a routine basis is less sensitive than radionuclide angiography in this diagnosis (4/13).

Angiocardiography↗
PubMed1983

Fluorescence label studies of the phase transitions of T7.

Optical density, fluorescence intensity, polarization and lifetime measurements were performed to analyze the temperature-induced phase transitions of phage T7 in several buffers. For labelling the intraphage DNA, ethidium bromide, proflavine and rivanol were applied for the proteins 1,6-diphenyl-1,3,5-hexatriene (DPH). In the temperature range of 20 degrees C-100 degrees C several structural changes of T7 were detected. Making corrections for light scattering by using integrating spheres and analyzing the fluorescence signals, the phase transition of intraphage DNA below 60 degrees C was interpreted as a superhelical relaxation phenomenon. The structural changes found by optical density at higher temperatures could be assigned to a change in the phage DNA or to a change in its protein part on the basis of fluorescence-melting results concerning DNA and protein labels. The effects of ionic strength and environment on the structural changes were studied.

Anti-Infective Agents, Local↗
PubMed1982

Consequences of the chronic cutaneous application of iodinated antiseptics on the thyroid function in the guinea-pig.

The effect of the chronic cutaneous application of iodine-containing substances on the thyroid function was studied in the guinea-pig. Six iodinated products were daily applied at the rate of 2 g/kg/day for 90 days. We find a quasi-abolition in the thyroid 131I-uptake (reflecting the transcutaneous absorption of free iodine) and an important transient thyroidal hyperproduction during the first month. Then, this primary hyperthyroidism induces a strong pituitary negative feed-back so that the levels of the circulating hormones T3 and T4 are normalized at the end of the experiment; a new hormonal balance is reached with a TSH level reduced by half compared to its normal value.

Animals↗
PubMed1981

Evaluation of myocardial perfusion and left ventricular function by 201T1 scintigraphy after dipyridamole.

201T1 myocardial imaging was performed at rest and after dipyridamole (0.44 mg/kg) on 50 patients with known or suspected ischemic heart disease. The dipyridamole had no effect in 14 patients (group Dip.0). In 17 patients (group Dip +/-) it significantly modified the contrast of the rest image (by increasing or decreasing a rest perfusion defect). In 19 patients (group Dip - Steal) the drug induced a paradoxical response interpreted as a coronary steal effect (an active region at rest becomes hypoactive after dipyridamole while an underperfused region at rest improves). All patients underwent coronary arteriography and left monoplane ventriculography; results were interpreted in relation to these angiographic data. The mean percentage of stenoses (per patient) was about the same in the three groups but it was found that, despite these stenoses, the patients of the group Dip - Steal had a good left ventricular function (EF = 0.62 +/- 0.12). On the other hand, the ejection fraction was very poor in the two other groups (0.50 +/- 0.17 and 0.48 +/- 0.17). Moreover it was found that: (1) the frequency of high grade or even complete obstruction was notably less in group Dip - Steal (P less than 0.05); (2) the frequency of angiographically visible collaterals was higher in group Dip - Steal (P less than 0.05); (3) the left anterior descending artery was less diseased than the right coronary artery in group Dip - Steal (P less than 0.05). These results have a real prognostic value for the assessment of the preserved cardiac performance in Dip - Steal patients despite severe stenoses, and are discussed in terms of compensatory collateral circulation and preservation of the coronary-flow reserve in the myocardium distal to a critical stenosis.

Coronary Circulation↗
PubMed1976

[Simultaneous study of the placental, myometrial and cervical circulations (indium 113 and anemometric thermometry). 2. Effect of xanthinol nicotinate].

The authors have studied the action of nicotinate of xantinol on the placental, myometrial and cervical circulations using an isotope technique (Indium 113) and anemometric thermometry. They show that this product in every case increases the flow through the cervix and has little action on the flow through the placenta, except that in rare cases it lessens it. The action on the myometrial circulation varies from woman to woman. There is a significant negative statistical correlation between variation in the circulation through the cervix and the placenta.

Adult↗