Aim. The ventricular pump function was studied in animals with serial-flash (dog), flash (chicken), and successive (toad) types of ventricular ex[scy]itation. Methods. Intraventricular blood pressure and isovolumic indices (dP/dtmax, dP/dtmin) of the left ventricle (LV) in birds and mammals and the single ventricle in amphibians were measured using the Prucka MacLab 2000 system. Data were obtained for sinus rhythm, supraventricular rhythm, and ectopic ex[scy]itation of the LV in chickens and dogs and the single ventricle in toads. Results. In dogs, basal stimulation of the LV resulted in significant reduction of the maximal systolic pressure in the LV. In chickens, maximal systolic pressure in the LV decreased under the pacing of the LV apex. The maximal systolic pressure in the ventricle of the toad decreased under ectopic excitation of the base and apex of the ventricle. The maximal rate of pressure rise in the LV in the chicken was insignificantly reduced under pacing of the LV. In the dog, dP/dtmax of the LV was decreased under basal pacing of the LV. In the toad, dP/dtmax was decreased to a higher degree under pacing of the ventriclar apex, as compared with supraventricular rhythm and pacing of the ventricular base. Isovolumic relaxation of the LV was slowed under LV basal pacing in the dog and was reduced under pacing of the LV apex in the chicken. In the toad, dP/dtmin was decreased to a higher degree under pacing of the ventricular apex, as compared with supraventricular rhythm and pacing of the ventricular base. Conclusions. Thus, the isovoiumic indices of the ventricular pump function in the toad were affected to a higher degree by apical pacing of the ventricle. In the dog, the pump function of the LV remained unchanged under apical pacing of the LV and impaired under basal pacing of the LV. The parameters of cardiac hemodynamics in the chicken were decreased under apical pacing of the LV.