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Med Tekh ; (1): 5-12, 2000.
Artigo em Russo | MEDLINE | ID: mdl-10740779


The paper deals with the acoustic noise that accompanies the work of artificial cardiac valves (ACV). The generation of a noise signal is a substantial disadvantage of ACV work after implantation. A highly sensitive solid-state probe was used to measure the noise signal. The disc ACVs Bjork-Shiley (USA), Omniscience" (Italy), MIKS, a basic (Russia), MIKS with an acoustic gap (Russia), and MIKS-3 were tested. The valves worked under model physiological flow. The disc valves of the MIKS series with an acoustic gap manufactured by ROSINVEST (Russia) were found to have the least noise.

Próteses Valvulares Cardíacas/normas , Acústica , Fenômenos Biomecânicos , Humanos , Ruído , Fatores de Tempo
Med Tekh ; (5): 21-9, 1998.
Artigo em Russo | MEDLINE | ID: mdl-9845878


The paper describes the main results of calculations and studies of a basically new model of a two-leaflet valve which greatly differs from the St. Jude two-leaflet valves used in clinical setting. The main difference is that the two leaflets are fixed on one turn axis displaced from the axis of symmetry of the ring-carrying valve. The paper calculates the values of displacement (eccentricity) of the leaflet turn axis against the axis of symmetry of the ring-carrying valve. The new model of the valve is conventionally called Butterfly. The eccentricity of the new valve for the whole dimensional series is calculated by using experimental findings and the conditions for optimizing an effective valve opening. The strength of the axis of leaflet turning and attaching is also calculated. The results of experimental studies of the hydrodynamics of two models of the Butterfly valve by employing photochromic imaging are presented. The results of rapid filming were used to determine the time of closure and opening of the two models of valves.

Próteses Valvulares Cardíacas , Hemodinâmica , Humanos , Modelos Cardiovasculares , Desenho de Prótese
Med Tekh ; (2): 11-8, 1998.
Artigo em Russo | MEDLINE | ID: mdl-9611743


The paper presents the results of examining the hydrodynamics of artificial heart valves (AHVs) manufactured in Russia and foreign countries. All the AHVs under study have been used in clinical practice for over 10 years and they are different in design. The hydrodynamics of AHVs was examined under static and pulsating flow through the valve. Photochromic imaging (PCI) was used for flow imaging. PCI is based on preparation of simulating blood (model physiological solution) in the medium, colour labels under laser radiation. The recording of colour label movement in the flow behind the valve using a speed camera makes it possible to follow flow hydrodynamics behind AHVs. The advantage of PCI over other methods is that the instant structure of flow behind the valve can be recorded just in the same section at any moment of an operating cycle. Based on the experimental data obtained by PCI, a procedure for comparative analysis of the hydrodynamic characteristics of AHVs was developed.

Próteses Valvulares Cardíacas , Hemodinâmica , Fluxometria por Laser-Doppler , Modelos Teóricos , Desenho de Prótese , Fluxo Pulsátil
Med Tekh ; (1): 10-20, 1998.
Artigo em Russo | MEDLINE | ID: mdl-9560812


The paper deals with the hydrodynamics of artificial heart valves (AHVs) used in clinical practice. It reviews and analyzes the studies of AHV hydrodynamics, as well as the hydrodynamic beds which stimulate physiological flow through the valve. Photochronic imaging (PCI) is proposed for examination of AHV hydrodynamic characteristics under model physiological flow. The hydrodynamics of different AHVs was tested on the beds simulating blood flow through AHVs by employing PCI. PCI involved preparation of model photochronic solution that simulates blood, colour labels by using laser radiation. In the model photochronic solution, 10(-6)-10(-9)-sec laser radiation gave rise to linear colour labels whose movement was recorded by a speed camera in the flow behind the valve. The profiles of speed behind the valves, the dimensions of congestive areas, the positions of flow detachment and regurgitation flow were calculated by a speed shooting in different periods of valvular performance. PCI defined congestive areas behind the valves, the areas of closed circulations, the sizes of reversing flow areas and examined the time course of flow behind the valves as a whole. The paper is of interest for AHV designers and cardiac surgeons who apply various AHVs.

Próteses Valvulares Cardíacas , Fotoquímica , Cor , Circulação Coronária , Lasers , Luz , Modelos Biológicos , Modelos Químicos , Modelos Estruturais , Fotografação , Soluções , Raios Ultravioleta