[The influence of pre-load on myocardial contractility indices. Experimental research (author's transl)]

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.