This paper focuses on the evaluation of dynamic pumps as an element of the assist unit from the standpoint of its capacity to pass and change the left ventricle's pulsations. Analyses of the dynamic equations of the pipelines and pump have been performed. The pump intensification capacity of the disc and blade pumps was computed. Theoretically it was determined and experimentally confirmed that the pump intensification capacity was defined by the performance of the pump head. It was also determined that the existing pumps (e.g., The BioMedicus Biopump and the Moscow Aviation Institute, OK) pass and attenuate the left ventricle pressure pulsations.

Intra-aortic counterpulsation with a balloon pump (IABP) was used in 63 patients with cardiogenic shock, heart failure after surgery with artificial circulation, internal lacerations of the myocardium, or unstable angina. It was found that the IABP was most efficient in conditions related to myocardial ischemia. Use of arteriovenous perfusion (in 11 patients) or artificial ventricles is indicated in severe perturbations of the pumping function of the heart. As experience has shown, cardiologic and heart surgery patients usually have multiorgan insufficiency. For this reason, it is necessary to use other artificial organs in complex treatment: artificial lungs, kidneys, livers, etc.

Two series of experiments were conducted to assess the potential of artificial ventricular bypass in restoring cardiac activity. One series evaluated use of a paracorporeal left ventricle in 17 calves; the other evaluated biventricular bypass in 11 calves. Module pumps with a seamless blood chamber of polyurethane were used. Pump function and system parameters were controlled by a Sinus VK-2 control system. Assisted perfusion began with the induction of ventricular fibrillation. The experiments showed that left ventricular bypass was an effective method for long-term maintenance of the hemodynamics during fibrillation, leading to certain biochemical corrections and restored electrical activity and myocardial contractile function. The hemodynamic state was maintained at a higher level with biventricular bypass and was accompanied by a greater percentage of restored myocardial function. Uneven restoration of contractile activity in the left and right ventricles points to the need for adequate support of both ventricles.

A comparative study of two methods of bypassing the heart with artificial ventricles (AV) was conducted: left atrium-aorta and left ventricle-aorta. The following factors permit left ventricular bypass to compete successfully with left ventricle-aorta bypass: creation of perfected pumps with low input impedance, use of materials with high resistance to thrombus formation for preparation of the AV and main connecting lines, and development of optimum methods of anticoagulant, disaggregation, and cardiac therapy so that there is no danger of thrombosis and hemorrhage, either experimentally or clinically. Thrombosis was the primary cause of death in only one case in a series of experiments on 15 calves with AV connected according to the atrium-aorta scheme. The positive changes in hemodynamics were approximately the same with the two methods.

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