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Biomedical subjects

M V Medvedev

Publications and source records attributed to M V Medvedev.

At least 19 recordsLinked to original sources
PubMed1999

Thermodynamics of photons in relativistic e+e- gamma plasmas.

Thermodynamic and spectral properties of a photon gas in e(+)e(-)gamma plasmas are studied. The effect of a finite effective mass of a photon, associated with the plasma frequency cutoff, is self-consistently included. In the ultrarelativistic plasma, the photon spectrum turns out to be universal with the temperature normalized plasma frequency cutoff as a fundamental constant independent of plasma parameters. Such a universality does not hold in the nonrelativistic plasma.

Journal Article↗
PubMed1993

[Uterine-placental-fetal blood flow and fetal cardiac activity during the ginipral treatment of premature labor].

Effects of intravenous and oral hinipral on the uteroplacentofetal blood flow and fetal heart work were studied in tocolytic therapy of preterm labor in 27 pregnant women at terms 25-35 weeks. Intravenous infusions of hinipral resulted in a significant reduction of the systolic-diastolic ratio in the umbilical artery, with the blood flow in the uterine arteries persisting stable, and in a significant reduction of the fetal heart rate and increase of fetal heart rhythm variability, as evidenced by cardiotocogram. In oral tocolysis the reduction of the umbilical artery was related to the pregnancy term; fetal heart rate and heart rhythm variability were within the normal range over the course of the investigation. The results evidence no negative effects of the drug on the uteroplacentofetal blood flow and fetal cardiovascular system both in oral and parenteral forms of tocolysis.

Abortion, Threatened↗
PubMed1992

[Doppler-metric and Doppler echocardiographic study of the nature and stage of disorders of fetal hemodynamics in intrauterine fetal growth retardation].

Pregnancy course, labor outcome, and doppler-metric findings were analyzed in 174 women, 98 with normal pregnancy (controls) and 76 with small-for-date fetuses when examined on weeks 28-41; the aim of the study was to analyze the pattern of hemodynamic disorders in small-for-date fetuses. A classification of fetal hemodynamic disorders has been developed, that distinguishes three types of disorders differing in severity: first degree--disordered fetoplacental circulation not reaching the critical values and satisfactory fetal hemodynamics; second degree--compensated disorders of fetal hemodynamics; third degree--critical state of fetal hemodynamics. Use of this classification in clinical practice will help define rational strategy of pregnancy follow-up.

Echocardiography, Doppler↗
PubMed1991

[Doppler-echocardiographic study of intracardiac hemodynamics in intrauterine fetal growth retardation].

Presents the results of Doppler echocardiographic examination of fetal hemodynamics, carried out in 90 women with normal pregnancy and small-for-date fetuses. Analyzes the specific features of fetal intracardiac blood stream in asymmetric and symmetric forms of development retardation. Discloses the regularity in changes of the ventricular diastolic function index in relation to placental resistance growth and of the maximal rate of transvalvular blood stream. Defines the Doppler echocardiographic signs of decompensation of myocardial contractility in conditions of high peripheral vascular resistance. Makes a conclusion on the relationship between changes of cardiac hemodynamics and centralized blood supply in small-for-date fetuses.

Blood Flow Velocity↗
PubMed1991

[Pathogenesis of deceleration in the prenatal period].

Comprehensive examination, making use of cardiotocography, dopplerometry, and doppler echocardiography, was carried out to disclose the contribution of fetal hemodynamic disorders to the pathogenesis of antenatal deceleration in 69 pregnant women. Disorders of both intracardiac fetal hemodynamics and of the fetoplacental circulation were revealed in all the cases with deceleration. Therefore, circulatory disorders underlie the pathogenesis of decelerations. The development of decelerations is related to the progressive deterioration of fetoplacental circulation and, specifically, to marked changes in the intracardiac hemodynamics in conditions of augmenting peripheral vascular resistance and hypoxia of the fetus.

Adult↗
PubMed1991

[Pathomorphology of spiral uterine arteries, umbilical vessels and placenta in disorders of maternal-fetal circulation].

The comparison of the spiral uterine arteries structure, umbilical vessels and placenta is performed in 16 women with normal haemodynamics and in 31 women with disturbances of mother-foetus circulation, and the data obtained were compared with results of dopplerometry made before the delivery. Three clinical groups are distinguished according to the predominant localization of the resistance to the blood flow: the first--with the domination of the spiral arteries obliteration (lack of gestational changes, hyperplastic arteriosclerosis) with a characteristic ultrastructural pathology of the syncytiotrophoblast microvilli, rheological disturbances in the intervillous space and large necroses of villi; the second--with a predominance of early immaturity of the stroma and capillaries or sclerosis and compression of foetal villous capillaries, i. e. with a reduction of a capillary bed and increase of the resistance to the blood flow; the third--with a predominance of the umbilical arteries narrowing and supporting villi and signs of a blood stasis in the foetal veins. Morphologic heterogeneity of the mother--foetus circulation disturbances should be taken into consideration when choosing obstetric tactics.

Arteries↗
PubMed1991

[Comparative study of dopplerometry and morphological study of placenta and uterine arteries in the evaluation of hemodynamic disorders in the "mother-placenta-fetus" system].

The paper gives the comparative results of Doppler examination of blood flow in the mother-placenta-fetus system and morphological examination of the vessels of the funis, placenta, and placental bed. The latter examination allowed all the cases of placentomaternal and placentofetal circulatory diseases to be divided into 3 groups. There was a clear-cut correlation between the Doppler metric and morphological findings.

Adult↗
PubMed1990

[Informative value of Doppler ultrasonography in predicting the development of gestoses and fetal growth retardation syndrome].

Doppler studies in 102 women with uncomplicated pregnancies have indicated that uteroplacental and fetoplacental circulations as low-resistant vascular systems develop at 13-16 week's gestation. Doppler examination early in the second trimester allows one to identify hemodynamic disorders in the materno-placental-fetal unit and predict their onset as well as toxemia of pregnancy and intrauterine growth retardation.

Adult↗