Effect of pronethalol on left ventricular volumes of dogs during hemorrhagic shock.

MYOCARDIAL LESIONS are produced soon after the onset of hemorrhagic shock in dogs (1, 2). It has been our contention that important factors in the pathogenesis of these lesions are the decreased filling of the ventricle (3) coupled with the increased endogenous secretion of catecholamines after hemorrhage. This leads to a situation in which the ventricle is beating strongly, with an incompletely filled chamber. Thus, the cardiac damage could, at least in part, be due to self-inflicted mechanical trauma resulting from this "squeezing" during the prolonged terminal isometric contraction. Pronethalol has been shown to prevent the myocardial lesions of hemorrhagic shock (4). The explanation for this finding may lie in the fact that pronethalol blocks the inotropic effects of n-sympathetic agents and thus would be expected to decrease myocardial contractility and produce larger ventricular volumes during shock. These possibilities have been evaluated in the present study by using biplane cineangiocardiographic technics to measure ventricular volumes.