[Should the presence of coiled blood flow in the left heart ventricle and aorta be taken into consideration when constructing artificial heart valves?].

The use of an original device developed by the authors which was introduced in the blood flow in experiments in dogs has confirmed the presence of coiled blood flow in different parts of the aorta. The rate, direction and angle of coiling were calculated. The results obtained suggest that the fact of coiling the blood flow should be taken into account when constructing new models of artificial valves of the heart in order to decrease the energy value of the cardiac output, to prevent injury of the formed elements of blood and thrombogenesis.

[Autovibration of a circular locking element of the aortic valve prosthesis].

Some experimental results when studying self-sustained vibrations of the ball locking element for an artificial heart valve are presented. The sign-changing dependence of a ball drag coefficient upon the ball stroke has been shown to cause these vibrations. Undamped oscillations result in a considerable growth of the valve hydrodynamic resistance.

[Flow past an artificial heart valve with a lens-shaped shutoff element].

An axisymmetric stream-line steady flow of perfect noncompressible liquid through the artificial heart valve with the lens-shaped shut-off element is considered. The liquid motion is described by a continuity equation for which the Dirichlet's problem in the plane of the valve meridional section is stated. Written in the finite differences the differential equation is solved by using a digital computer (ZDBM-220).

[Temporal characteristics of the movement of the cut-off elements of artificial heart valves in a pulsing flow].

A comparative investigation of time characteristics of the movement of artificial heart valves with spherical, hemispherical and lentil-shaped obturative elements under non-stationary conditions was carried out. It has been found that it is practically impossible to avoid the delay in the valve closing and opening, as well as the regurgitation phenomena, on the valve prothesis, due to the inertia of obturative elements and attached masses. A searching for new models of the heart valves should go on.

[Pressure distribution on the surface of the cut-off elements of artificial heart valves].

With hydroaerodynamic investigations into pressure distribution on the surface of blocking components in artificial cardiac valves in the shape of a sphere, semisphere, lens and a disc opening at an angle serving as a basis a quantitative evaluation of the arrangement for the flow separation, evacuation peak regions and congestion zones is given. The highest velocity, greatest evacuation and shear stress occur in a flow-past of a valve having a shape of the lens. The disc valve opening at an angle, as concerns its hydrodynamic characteristics, is superior to the valves of all the other designs considered in the present work.

[Comparative hydrodynamic study of artificial heart valves in pulsating flow].

A comparative hydrodynamic study of artificial heart valves with spherical, hemispherical and lentil-shaped obturative elements has been carried out under the non-stationary conditions. The valves resistance coefficient is higher in the lentil-shaped valves. With the increase of pulse rate the stroke volume of the valves of all the types drops, and the regurgitation increases.