[Rheocardiographic studies on the accuracy of cardiac stroke volume models].

Some results of the studies on the accuracy of detecting pulsating stroke volume from rheocardiograms are discussed. Using a physical model it is shown that resulting values are strongly conditioned by relative positions of electrodes and pulsating volume, its shape, and the geometry of conducting medium. An approximate value of the stroke volume may be derived from the semiempirical formulae coupling relative variations of the resistance and the volume.

[Study of the functional characteristics of intra-aortic balloon pumps].

The authors propose a classification for intraaortal balloon-pumps. Their functional characteristics were studied on a new hydrodynamic stand. A mathematical model simulating the balloon operation, applicable for designing balloon systems, is offered.

[Optimal mode of operation of an artificial heart].

Artificial heart operation was estimated from the view point of minimum energy consumption for the blood transport. The operation mode without breaks proved to be more economical in this respect, as compared to the mode with breaks during systole or diastole. A special control device has been designed just for the provision of uninterrupted artificial heart operation.

[Study of the pumping function of devices for direct mechanical heart massage].

A method permitting to define the efficiency of devices designed for direct cardiomassage on a special hydrodynamic stand is given. The results are presented, obtained with the variation of the main functional parameters which ensure maximum capacity of the device. Factors influencing the cardiomassage efficiency were determined.

[Hydrodynamic stands for testing assisted circulation and artificial heart apparatus].

Problems arising in devising the assisted circulation apparatus and artificial heart can be solved only with investigations conducted on hydrodynamic models of the circulation system--the stands. An analysis of literature sources dealing with test stands justifies their classification according to the purpose, the types of tests, the specific structure and basic characteristics. It is necessary to proceed with further improvement of the stand equipment in the direction of creating a sufficiently accurate imitation of the anatomic structure and resilient properties of major arteries and veins, of constructing a geometrical and elastic model of the aorta, of pressure and flow control instruments at different points of the vessels, of the ones regulating the energy parameters, as well as of working out criteria for effectiveness of the devices to be used.

[Comparative study of different artificial heart designs].

The results subsequent to investigations of 3 artificial heart constructions effected on a hydrodynamic stand are reported. The values of the artificial heart resistances during the systole and diastole were determined, these being shown to stand close to one another in all of the designs under review.

[Method of bench testing an artificial heart].

A procedure for bench trials of the artificial heart (AH), that comes to determining the relationship between the AH performance and the duration of the systole with constant pressure differentials at the in- and outlets of the AH and pulse rate. The results of the AH trials by the proposed procedure are described.