[Analysis of the exercise induced changes of the atrial vectorcardiogram in mitral valve stenosis by means of electronic elaborator].
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Biomedical subjects
Publications and source records attributed to B Colla.
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A programme of on-line automated analysis of ECG exercise graphs relative to the CB5 derivation is described. The various operations may be subdivided into the following phases: 1) performance; 2) mean complex; 3) identification; 4) calculation and print-out of parameters; 5) filing. Automatic analysis of exercise ECG's eliminating artifacts present in graphs and obtaining parameters that are not respectively assessable, facilitates the development of rigorously objective diagnostic guidelines. The filing of indices on magnetic tape opens the way to subsequent statistical analysis of extreme usefulness in testing extensive populations.
The use of computers in the exercise of electrocardiography is considered. The problems related to this use concern the choice of leads, the filtration of the signal, the recognition of characteristic segments of ECG, the calculation of various indexes and their statistical evaluation for diagnostic purposes. The authors use a bipolar derivation filtered by averaging and digital filters. The characteristic points of ECG are recognized by the analysis of the curvature. The Tchebycheff coefficients of the S-T tract are evaluated; they appeared to be a very good means for judging positive and negative cases.
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The behaviour by increasing the ventricular volume of several parameters and indices proposed for measuring the cardiac contractility has been determined in isolated guinea pig hearts beating under isometric conditions. Particularly, V max calculated on the total pressure has been compared with the Vmax calculated on the developed pressure. Whilst the later showed to be independent of preload changes, Vmax was calculated on the total pressure, decreased by changing the ventricular volume. Moreover, it showed itself to be independent of pre-load changes. An index proposed recently obtained from the plot (P, P'), as ratio between the positive portion of the area and the developed sistolic pressure wals also demonstrated.
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The hemodynamic effects induced by the injection in the pulmonary artery of the new nonionic water soluble contrast medium Iopamidol were compared with those obtained by the injection of two other currently used contrast media (meglumine diatrizoate and sodium iothalamate). The experiments were carried out in nine mongrel dogs. Hemodynamic variables were continuously measured prior to, during, and for 8 minutes after injection of the contrast media. Injections of iopamidol produced significantly smaller decreases in aortic pressure (p less than 0.01), contractile indices (p less than 0.01), and peripheral resistances (p less than 0.01), and changes in heart rate and in cardiac output were less pronounced. At 3-4 minutes after injection, an increase in Vmaxd was observed with all three contrast media, but it was significantly lower after injecting Iopamidol. The role of hyperosmolality in causing cardiovascular changes is discussed. The less significant changes induced by Iopamidol appear to be the result of its lower osmolality, which is about a third that of meglumine diatrizoate or sodium iothalamate.
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