[Mechanism of hemodynamic effects of right cardiac shunting]

The impact of right cardiac shunting on the hemodynamic changes of the cardiovascular system was examined in acute experiments on intact dogs. The ventricular pacemaker (VP) which is a "Modul" Russian model was connected by the scheme: right ventricle-pulmonary artery. The first 20 minutes of VP operation in the complete right ventricular unloading mode resulted in increased left cardiac contraction force and rate and in elevated vascular pressure. The subsequent functioning of VP was followed by a reduction in positive inotropic effects. The changes occurring in left ventricular function and vascular tone were associated with the inclusion of mechanisms responsible for intracardiac nervous regulation to blood filling changes of the right heart due to their shunting. A fall in right ventricular pressure was perceived by myocardial mechanic receptors, by stimulating the adrenergic neurons of the intracardiac nervous system whose action is short and effected from one state to another in the transitional period.