Biomedical subjects
Publications and source records attributed to M Fauchet.
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In the setting of cardiac testing, NMR spectroscopy should occupy a major place since it allows a noninvasive serial assessment of the biochemical status of a functioning heart and could be coupled with other investigations to provide simultaneous recordings of both metabolic and functional data from a definite myocardial area. In the future, NMR imaging may become a clinically viable tool providing localized non-invasive biochemical measurements in the heart.
The authors have only reported cases responding to the following criteria: A) necessarily: 1) Clinical appearance of algodystrophy. 2) Intense hyperfixation of the bone scan. 3) X rays repeated a sufficient number of times always normal and submitted to the judgement of six rheumatologists not forewarned, to eliminate the subjective factor in the diagnosis of normality. 4) Clinical cure within the usual period. 5) Return to normal of the bone scan. B) Eventually: 6) Proved decalcifying algodystrophy from another joint site in the past history. 7) Histological appearance compatible with algodystrophy on bone biopsy. Four cases are presented (hip one case, knee two cases, ankle one case) which fulfill the five necessary criteria. The course seems shorter than in the classical decalcifying forms: 2 months instead of 4 1/2 months on average for the hip; 5 months instead of 7 months on average for the knee; 5 months instead of 12 months on average for the foot. This short course is in favour of the theory of early and rapid reconstructive bone changes, which do not leave the algodystrophy the time to demineralise the bone more than 30 to 50% which is the time necessary for the increased radiographic bone transparency to become clear.
The effect of parathyroidectomy on left-ventricular function was evaluated in chronic-haemodialysis patients with advanced hyperparathyroidism. Radionuclide angiocardiography (22 patients) and ultrasound echography (8 patients) revealed a significant increase in left-ventricular ejection fraction 1--2 weeks after parathyroidectomy. This improvement was associated with an augmented cardiac index (radionuclide method) and with an increase in mean velocity of circumferential myocardial fibre shortening (echocardiography). Circulating blood volume and erythrocyte space, as well as arterial blood-pressure, had changed little after parathyroidectomy, whereas plasma calcium, phosphate, and immunoreactive parathyroid hormone were significantly lower after surgery. Thus, correction of severe hyperparathyroidism led to a significant improvement in cardiac performance.
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Isochronous cyclotrons used to accelerate different charge particles (protons, deuterons, alphas...) at variable energies, have important medical applications, for neutron teletherapy, in vivo or in vitro activation analysis or production of short-lived radioisotopes for nuclear medicine. The characteristics of the cyclotron presently available are described for these three applications (low energy "compact" cyclotrons, cyclotrons of intermediate and high energies), and their advantages are discussed from the points of view of the medical requirements, the financial investments and the results obtained.
The hyperemic response induced by the tri-iodinated contrast agent injection for coronarography assesses functional value of the arteriolar areas of coronary distribution. The intracoronary injection of two kinds of micropheres labeled with gamma emitter radionuclides of different levels of energy (99m-Technetium and 113m-Indium) provides comparison of the studied areas-scintigraphies at rest and during hyperemia.
Eighteen cases of cardiac transplantation have been carried out for 16 recipients since October 1973, there being 8 survivors at present. The importance of screening in such a treatment is vital. It is a simple method, easy to control, can be carried out at the bedside, is reproducible, reliable, and completely harmless, and by allowing the haemodynamic function of the graft to be seen at all times, helps in the marching of the donor and the recipient, in following the function of the graft in the immediate post-operative period, and in discovering rejection crises, and evaluating the long-term fate of the transplant.
Comparison between the effective systemic ejection fraction defined by radiocardiography and cardiac chambers scanning, and the whole left ventricular ejection fraction calculated by cineangiocardiography allows an accurate assessment of mitral and aortic regurgitation extent. In case of both mitral and aortic insufficiency, each regurgitation can be quantitatively dissociated by means of the aortic isotopic dilution curve recorded at the same time as the radiocardiogram.
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Selective intracoronary injection of microspheres labelled with radioactive substances which emit gamma rays with different energy levels (Indium 113 m and Technetium 99 m) allows us to explore by scintigraphic methods the areas of distribution of the two coronary arteries. Having been carefully calibrated, the particles are injected in limited numbers, and block the precapillary arterioles, where they gradually diminish in number. Scintigraphic examination is carried out in various projections (anteroposterior, left anterior oblique and right anterior oblique) immediately after coronary arteriography. Coronary scintigraphy allows us to establish the integrity of the distribution network of a coronary trunk which appears normal on coronary arteriography, to visualise the diminution of flow caused by a stenosed but patent trunk, and to visualise the extent of the collateral circulation and the quality of revascularisation achieved by an aorto-coronary bypass operation.
The combination of radiocardiography with scintigraphy of the cavities of the heart allows us to calculate the effective systemic ejection fraction. The systolic volume effectively ejected into the systemic circulation is obtained from radiocardiography using Stewart-Hamilton's principle. It is correlated with the left ventricular end-diastolic volume as calculated by planimetry on the scintigraphic record of the cavities of the heart, making due allowance for the geometrical axis of the heart. The ejection fraction measured by this isotope method has been compared with the ejection fraction measured by selective left ventricular cineangiography, both measurements being carried out at an interval of less than 48 hours in 100 patients without valvular disease. The results show an excellent correlation between the two methods (r = 0.94). In the 15 cases where the haemodynamic status of the ventricule appeared to be normal, the ejection fraction meastured by the two techniques was 0.65 +/- 0.04 and 0.66 +/- 0.04 respectively. In those patients with valve disorders with incompetence, the effective systemic ejection fraction is always lower than the total ejection fraction given by cineangiography. The difference corresponds with the fraction of the blood volume which is regurgitated.
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Reproductibility of the radiocardiographic method using 42 Potassium has been verified. Coronary blood flow has so been measured in 50 control subjects and coronary heart disease patients, at steady state and during auricular pacing at 150 beats per minute. In control subjects group, under auricular packing coronary blood flow increases by a mean value of 15%; on the other hand it decreases by a mean value of 32% in coronary heart disease patients bearing obvious coronarography lesions. The cardiac output coronary fraction increases by a mean value of 27% in the control subjects group; it remains unchanged in coronary heart disease patients. On the contrary this coronary fraction increases in a significant way after functional aortocoronary bypass.
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Computer exploitation of some parameters of the radiocardiogram and of the pressures measured by catheterization in a series of 678 subjects, studied both in Paris and in Prague, has made it possible to establish regression equations providing the rates of mean pulmonary arterial and wedge pressures together with the systolic right ventricular pressure on the basis of the radiocardiogram data. The latter was obtained by the conventional technique of the isotope dilution curves or by gamma-angiocardiography. Easy repetition of radiocardiography makes it an interesting investigation for the haemodynamic follow-up of the patients with heart disease.