[Ultrasound markers of the genetic pathology and early hemodynamic changes in human embryo]

First trimester nuchal translucency (NT) and ductus venosus reverse blood flow (DVRBF) are used as ultrasound markers (UM) to determine the risk of fetal aneuploidy, heart defects and subsequent maternal preeclampsia. One pathophysiological explanation for these UM, encompassing both normal and pathological outcomes, is the development of transient heart failure due to increased vascular resistance (afterload). Left ventricular isovolumic relaxation time (LV IRT) was demonstrated as sensitive index of afterload increase in the second and third trimester fetus. The objective of study was to determine LV IRT in normally developing embryos and embryos with early UM of chromosomal and cardiac abnormalities and to test the hypothesis of embryonic hypertension as a cause of transient heart failure. An ultrasound study in 122 normally developing and 27 human embryos with increased NT (>3 mm) and DVRBF at gestational ages 11-14 weeks was perfomed. Mean LV IRT (41 +/- 3 ms) was 36.6 percent longer in embryos with UM as compared to the normal subset (30 +/- 2 ms) (p < 0.001).

[The intrauterine programming of adult and children's disesases]

The intrauterine programming hypothesis proposed that cardiovascular and metabolic disease originate through developmental plasticity and fetal adaptation arising from failure of the materno-placental supply of nutrients. The hypothesis is supported by experimental data in animals indicating that maternal nutrition can program long term effects on the offspring. The intrauterine conditions in which the fetus develops have an important role in regulating the function of its physiological systems later in life. Intrauterine programming of physiological systems occurs at the gene, cell, tissue, organ, and system levels and causes permanent structural and functional changes, which can lead to overt disease, particularly with increasing age. The physiological prevention of disease programming is discussing.

[Compensatory hypertension and fetal heart remodeling: from adaptation to pathology]

Left ventricular (LV) isovolumetric relaxation time (IRT), shape and LV wall movement uniformity were assessed in 102 appropriate for gestational age (AGA) human fetuses and 36 fetuses with intrauterine growth retardation (IUGR). In 28 AGA newborns and 26 IUGR infants rennin and angiotensin 1 concentrations were assessed in umbilical cord blood by radioimmunoassay. Systolic blood pressure (BP) was also measured in these infants. The IRT in IUGR fetuses was more (50.9+/-8.6 ms) than in the AGA fetuses (42.8+/-6.7 ms, p < 0.01). The mean BP in the IUGR newborns was greater (76+/-5 mm Hg vs 60+/-6 mm Hg, p < 0.01) than in the AGA fetuses. Rennin and angiotensin 1 concentrations were 1.61- and 1.56-fold greater in the blood of the IUGR newborns than in the AGA infants. A chronic hypertension in placenta perfusion increase in the IUGR fetuses was proposed. The changes in LV shape and uniformity of wall movement (remodeling) are considered to be the result of chronic increase in afterload. Rennin-angiotensin activation and LV remodeling as an adaptive reactions of antenatal period could promote the arterial hypertension development in later life.

[Contraction-relaxation dynamics and mechanical restitution in the developing myocardium of the chick embryo]

Parameters of the contraction-relaxation cycle and mechanical restitution (MR) were assessed in isolated ventricular preparations of 3- and 4-day chick embryos (EM) and posthatched (PH) chicks. Ryanodine reduced the relaxation rate in the EM but increased it in the PH chicks. It also suppressed a rest-induced potentiation and the MR in all the preparations. Low Na superfusion significantly suppressed the relaxation and decreased the rest potentiation in the myocardial preparations all ages. The findings substantiate existence of a sarcolemmal Ca pool which participates in regulation of twitch parameters and Ca outflux via the Na-Ca exchange.

[Hemodynamic status of the mother and fetus in pregnant women with gestosis during abdominal delivery under different anesthesia methods]

Pregnants in the third trimester with medium- and severe gestosis were divided into 3 groups according to types of maternal and fetal hemodynamics: 1) controls (n = 58 pts); 2) eukinetic type (n = 54 pts); and 3) hypokinetic type (n = 55 pts). Each group was subdivided into 3 subgroups according to administered types of anesthesia for cesarean section (epidural, spinal, and general). Central hemodynamics of the mother, fetus, and fetoplacental complex was studied. Use of different anesthesias in woman with normal pregnancy did not affect the hemodynamics, and therefore any type of anesthesia can be used in cesarean section. In pregnants with gestosis, the eukinetic hemodynamic and compensated or subcompensated placental insufficiency the optimal anesthesia was epidural and spinal. For pregnant with hypokinetic circulation and subcompensated or decompensated placental insufficiency epidural anesthesia is preferable.

[Anesthetics and the developing heart]

Effects of various anesthetics on the myocardium of developing heart are reviewed. Anesthetics suppress myocardial contractility in a fetus and newborn more intensively than in an adult. This is due to immature cell mechanisms regulating cardiomyocyte contractile activity and specific effect of the autonomic nervous system on the heart. It is obvious that the problem of interactions between anesthetics and developing cardiovascular system remains important because of constant introduction of new drugs with new cell and organ effects into practical anesthesiology.

[Experimental-theoretical study of the force-interval relationship in the developing chicken myocardium]

The force-interval relationship was studied on myocardium preparations from chick embryos and hatched chickens. It is shown that the force-interval relationships of myocardium change during ontogenesis. A negative staircase (a decrease in the isometric force with increasing stimulation rate) in the chick embryo myocardium and a positive steady-state relationship in hatched stage myocardium were revealed. Changes in the force after switching from one stimulation frequency to another, the effects of poststimulation potentiation, as well as responses to the introduction of pauses and extrasystols at a constant stimulation rate were recorded. All the effects observed in the transient processes in preparations from hatched stage myocardium were more pronounced than in embryo myocardium. Our previous mathematical model of calcium recirculation in cardiomyocytes was adapted for simulating the main features of force-interval relationships in embryonal and relatively developed myocardium. The main source of regulatory calcium in the model of hatched stage myocardium is sarcoplasmic reticulum. In the model of embryo myocardium, it was postulated, based on data available in literature, that the main regulator of contractile response of the muscle is calcium that enters cardiomyocytes from extracellular medium. To describe force-interval relationships, by this model, the decreasing dependence of the entry of extracellular calcium on the intervals between stimuli was introduced.

[The role of intra- and extracellular calcium sources in the rhythmic inotropic regulation of isometric contractions in the chick embryo myocardium]

Isometric contractions and force-frequency relationships (FFR) were assessed in isolated ventricular preparations of 3- and 4-day chick embryos (EM) and posthatched (PH) chicks. Pacing protocols for the FFR assessment were applied in normal buffer, buffer with 50% and 25% of normal Na+ concentration, and in buffer with ryanodine. PH myocardium showed greater peak force and more prominent FFR than EM. 50% low Na+ superfusion induced positive inotropic effect and increase in the FFR in PH and EM. 25% low Na+ superfusion induced negative inotropic effect and suppressed FFR more prominent in EM. Ryanodine more suppressed FFR in PH myocardium. The observed age-dependent differences substantiate the fact that Na-Ca exchange plays a leading role in the FFR regulation in early embryonic myocardium and sarcoplasmic reticulum plays a leading role in PH myocardium.

[Non-invasive evaluation of systolic and diastolic functions of the left ventricle in newborn infants]

To assess possible changes in myocardial contractile function and relaxation occurring after mild perinatal asphyxia, maximal blood pressure and M-mode echocardiograms should be registered simultaneously in 32 normal term newborns (group 1) and in 22 term asphyxiated newborns (group II). The slope of end-systolic pressure-dimension relation (ESPDR) was used as a reliable index for evaluation of the myocardial contractility. The slope of ESPDR and some indices of ventricular relaxation decreased in newborns from group II. It is suggested that ESPDR and parameters of left ventricular relaxation and filling can serve as early and sensitive indices of hypoxic myocardial damage.

[Pre-clinical diagnosis of toxemia in the second half of pregnancy in a day-care hospital]

In this study +the purpose to improve diagnostic precision in preclinical forms of late toxemia, the central and peripheral circulation and hemostasis have been evaluated in women during their four day-stay visits scheduled for a pregnancy. Transition of normal pregnancy to "++pre-toxemic" was most commonly seen in the second trimester. Platelet counts and levels of fibrinogen and beta-fibrinogen proved to have the highest predictive value. A decision-making rule was designed for categorization of pregnancies into normal and "++pre-toxemic" and was found to have a 90% efficiency.

[Evaluation of ontogenetic changes in the chrono- and inotropic functions of the rat myocardium under a random stimulation regimen]

The relationships between isometric contractions and duration of interstimulus intervals, which were changed randomly, were assessed in myocardial strips of adult (AR) and newborn rats (NR). The highest coefficients of variation of contractions amplitude were seen in AR and lowest those in preparations of 1-3 day of life NR. The "force-interval" autoregression coefficients were estimated in different Ca2+ concentrations, their differences being due, probably, to ontogenetic changes.

[Myocardial contractility in newborn kittens under a physiologic loading regimen]

The angles of ramp of normalized dependences: "strength-velocity" and "terminal systolic length--terminal systolic strength" proved to be lesser under physiological loads in isolated papillary muscles of newborn kitten as compared with adult cats. Adrenaline increased the slope of these dependences up to the values characteristics of the adult cat's myocardium in saline. The data obtained suggest a low level of the calcium activation and ATPase activity of contractile proteins of the myocardium in newborn kitten.

[Mechanism of postextrasystolic potentiation of the myocardium]

Combined effects of poststimulation and postextrasystolic potentiation (PESP) were studied in the rat papillary muscles. The constant PESP augmentation of isometric force triggered by extrasystolic stimulus was shown for 2-8 poststimulatory potentiated contractions. The PESP was not dependent upon the Ca2+ concentration within the 0.5-1.2 mM range. The findings corroborate the postulate that the PESP in cardiomyocytes is associated with special Ca2+ store which is triggered by two APs: regular and extrasystolic ones.

[Effect of paired stimulation on the electrical and mechanical activity of myocardial cells in congenital and acquired heart defects]

Thin myocardial strips were dissected from the papillary muscles of patients undergoing mitral valve replacement (group I) and atrial tissue of patients undergoing the correction of congenital septal defects (group II) and mitral stenosis (group III). Electrical activity and isometric tension were measured. Paired stimulation (PS) with time intervals of 250-350 ms and 380-440 ms activated two action potentials (AP) for each potentiated contraction (80 and 70% of force increase, respectively) in bundles of groups I and III. Strips of group III had depressed level of resting potential (RP) and different types of AP including AP with additional spike activity in the plateau phase. The inotropic effect of PS depends on the level of the resting potential. If RP was more than 45 mv PS activated two AP or one doubled AP for each potentiated contraction (80-120% of force increase). If RP was less than 35 mv PS was not able to initiate doubled AP and to initiate the increase of contractility. Epinephrine (10(-6) g/ml) increased the depressed RP and AP in group III bundles and potentiated the inotropic effect of PS in groups I and III. Verapamil (2 X 10(-6) g/ml) inactivated the doubled AP and abolished the inotropic effect of PS in group III strips. It is supposed that additional inflow of Ca during excitation produces the inotropic effect of paired stimulation in human myocardium.

[Kinetics of myocardial isometric relaxation in patients with congenital and acquired heart defects]

The kinetics of isometric relaxation was examined in an isolated myocardium of patients undergoing surgical correction of mitral stenosis (MS), congenital septal heart defects (SHD) and on papillary muscles (PM) of patients suffering from mitral valvular insufficiency. The relaxation of MS preparations is slower than that of SHD that manifests in the decrease of the characteristic constants K and alpha. PM relaxation is slower than that of the rabbit ventricular muscle. Adrenaline and the increased stimulation rate accelerate the relaxation of the preparations of all groups (the greatest increase is seen in MS). Verapamil and paired stimulation slow down the constants. It is suggested that the action potential duration influences the relaxation constants in PM and MS preparations but not SHD. The constants in question seem likely to be independent of the myocardial inotropic state.

[Contractile reaction of the myocardium of patients with heart diseases to chemical scarification of cell membranes]

Strips of the myocardium from the auricula atria of patients suffering from mitral stenosis (MS) and septal defects of the heart (SDH) removed during the operation were treated with ethylenediaminetetraacetic acid (DETA)--3mM--to increase the cell membrane permeability (scarification). The mechanical response of the contractile proteins to the change in the Ca2+ was recorded in the ethylene-hexaaminetetraacetic acid (EHTA)--3mM--against the background of increased membrane permeability to the Ca-EHTA complex permitting to regulate Ca2+ concentration in myofibrillae from 10(-9) to 10(-4)M. As shown, with the same threshold concentrations (5.10(-8)M) and saturation concentrations (10(-4)M) of Ca2+ the strips from the patients with MS developed the maximal tension per cross section unit of the strip half as great as the preparations from patients with SDH, this indicating a possible affection of the contractile proteins in the hearts of patients with MS. The ratio between the tension amplitudes under conditions of a complete calcium activation of the contractile proteins and a single isometric contraction for the preparations obtained from the patients with MS was 8 to 10, and with SDH--from 4 to 5. It is supposed that this was the result of more pronounced changes in the apparatus of electromechanical conjugation of the myocardium of patients suffering from MS.