[Medinzh artificial cardiac valves].

The method of photochromic imaging was used to study the flow structure behind MEDINZh artificial cardiac valves. The flow structure behind three models of MEDINZh artificial cardiac valves (basic bicuspid model and two models under development) was studied experimentally under conditions of model physiological flow. Momentary flow rate profiles demonstrating the dynamics of the flow structure behind the valves were determined at various stages of the valve operation. The flow structure behind the artificial cardiac valves was studied in two perpendicular planes. The flow structure in front of the valves at the closing stage was also studied. The hemolysis level was experimentally determined under conditions of model physiological flow for the following six models of artificial cardiac valves: bicuspid valves CARBOMEDICS (USA), MEDINZh (Russia), MEDINZh N (Russia), and ROSCARDICS (Russia); disk valve MIKS (Russia); and a tricuspid valve (Germany).

[Experimental study of the hydrodynamics of polyurethane tricuspid heart valves].

Photochromic imaging, a new experimental hydrodynamic method, was used to study the flow structure behind polyurethane cardiac valve implants. The method is based on the sensitivity of model physiological medium to laser radiation. Color labels appear in 10-6 sec in the flow behind the valve under exposure to laser radiation. The motion of color labels in the flow is recorded with a high-speed camera. This makes it possible to determine the flow structure behind the valve. The flow structure behind three types of polyurethane cardiac valve implants was experimentally studied under conditions of model physiological flow. A polyurethane tricuspid valve with inner diameter 24 mm, a polyurethane tricuspid valve installed in a polyurethane tube, and a polyurethane tricuspid valve installed in a housing with Valsalva sinuses were studied. Complex flow structure was observed behind the cardiac valves. The complexity of its structure is explained by specific properties of valve construction. Flow rate profiles were determined for each moment of valve operation. These profiles show the dynamics of flow structure behind the valves.