The biochemical model of excitation-contraction coupling in cardiomyocyte is presented and the validity of simulations of both physiological and pathological processes is discussed. The model of regulatory and actomyosin subsystems, even if it is rather simple in its regulatory subunit, gives results well consistent with experimental data. Specifically, intracellular free calcium levels ([Ca2+]i) were computed under various states of sarcoendoplasmic reticular Ca2+-ATPase (SERCA2) and compared to experimental findings. Computed results reproduced well both the increase in resting [Ca2+]i level and the attenuation of [Ca2+]i decline commonly observed in heart failure. Thus the computational simulations could help to identify core relations in studied systems by comparing results obtained using similar models of various complexities., M. Mlček, J. Neumann, O. Kittnar, V. Novák., and Obsahuje bibliografii
Glucocorticoids (GCs) are steroid hormones produced by the adrenal cortex in reaction to stress stimuli. GCs production is not stable over a 24-hour period; the plasma concentration peaks in the morning (approximately upon awakening) and then the plasma levels decrease, reaching the nadir in the evening. In our experiments, the levels of cortisol, cortisone, DHEA and DHEAS were tested in young female pigs (n=23) during heart catheterization at two different day times (in the morning and in the afternoon). The non-parametric Mann-Whitney test for statistical analysis was used. We found only minimal statistical differences in studied markers between the morning and afternoon group (p>0.05). The absence of circadian variation in GCs levels could originate either at an early age of our experimental pigs, or in stressful conditions on the experiment day, or most likely the day before (e.g. social isolation, fasting, transport, and catheterization), respectively. We can conclude there is no difference in the stress load between morning and afternoon experiments, and therefore we can assume the stress load is not a limiting factor for the timing when catheterization should be preferably performed., H. Skarlandtová ... [et al.]., and Obsahuje seznam literatury
Early recognition of collapsing hemodynamics in pulmonary embolism is necessary to avoid cardiac arrest using aggressive medical therapy or mechanical cardiac support. The aim of the study was to identify the maximal acute hemodynamic compensatory steady state. Overall, 40 dynamic obstructions of pulmonary artery were performe d and hemodynamic data were collected. Occlusion of only left or right pulmonary artery did not lead to the hemodynamic collapse. When gradually obstructing the bifurcation, the right ventri cle end-diastolic area expanded proportionally to pulmonary artery mean pressure from 11.6 (10.1, 14.1) to 17.8 (16.1, 18.8) cm 2 (p<0.0001) and pulmonary artery mean pressure increased from 22 (20, 24) to 44 (41, 47) mmHg (p<0.0001) at the poin t of maximal hemodynamic compensatory steady state. Sim ilarly, mean arte rial pressure decreased from 96 (87, 101) to 60 (53, 78) mmHg (p<0.0001), central venous pressure increased from 4 (4, 5) to 7 (6, 8) mmHg (p<0.0001), heart rate increased from 92 (88, 97) to 147 (122, 165) /min (p<0.0001), contin uous cardiac output dropped from 5.2 (4.7, 5.8) to 4.3 (3.7, 5.0) l/min (p=0.0023), modified shock index increased from 0.99 (0.81, 1.10) to 2.31 (1.99, 2.72), p<0.0001. In conclusion, in stead of continuous cardiac output all of the analyzed parameters can sensitively determine the individual maximal compensatory response to obstructive shock. We assume their monitoring can be used to predict the critical phase of the hemodynamic status in routine practice., J. Kudlička ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
Gestational diabetes mellitus (GDM) represents additional risks to both mother and infant. Moreover it increases a woman's risk of cardiovascular disease in the postpartum. The aim of our study was therefore to detect changes of both the QT dispersion and the electrical heart field that could be typical for GDM. Body surface potential maps were obtained using the Cardiac 112.2 device from 26 young women with GDM and 54 young healthy pregnant women in the 36th week of pregnancy. The same recordings were obtained from 18 healthy women in the same age (19-36 years). The average QT dispersion (±SD) in women suffering from GDM was significantly higher (107±25 ms) both than in those with physiological pregnancy (73±18 ms) and than in the normal subjects (34±12 ms) (P<0.001). Moreover we have found in GDM patients shorter QRS complex 82.0±6.8 ms vs. 89.5±8.2 ms in healthy pregnant women and 90.8±7.9 ms in the control group (p=0.011), more horizontal electrical heart axis [16.4±20.1° vs. 42.4±28.7° and 74.6±39.2° respectively (P<0.05)] and lower some depolarization and repolarization amplitudes on isopotential and isointegral maps. According to these results we suppose that described electrocardiographic changes reflect a deterioration of the complete process of ventricular depolarization and repolarization in GDM., E. Medová, ... [et al.]., and Obsahuje seznam literatury
The aim of the study was to detect changes of both the QT dispersion and T-loop morphology resulting from the changed spatial position of the heart during pregnancy. Electrocardiographic and vectorcardiographic recordings were obtained from 37 healthy women 19-36 years old in the 36th to 40th week of physiological pregnancy and 2 to 6 days after delivery. The same recordings were obtained from 18 healthy women of the same age. The average QT dispersion (±S.D.) in normal subjects was significantly lower (34±12 ms) than in those in late pregnancy (73±18 ms) (P<0.001). The average amplitude of T-loop (Ta) in women in late pregnancy was significantly (P<0.001) smaller (532±98 mV) and the width of T-loop (Tw) was wider (21.24±11.48 deg) than in the control group (793±114 mV and 7.17±3.02 deg, respectively). The partial post-partum restoration of all parameters was not significant. In all groups, the QT dispersion was significantly correlated with Tw but not with Ta. According to these results we can conclude that the QT dispersion is an indirect reflection of the complete process of ventricular repolarization, reflected in the morphology of the T-loop., M. Lechmanová, O. Kittnar, M. Mlček, J. Slavíček, A. Dohnalová, Š. Havránek, J. Kolařík, A. Pařízek., and Obsahuje bibliografii
The growth in the experimental research of facilities to support extracorporeal circulation requires the further development of models of acute heart failure that can be well controlled and reproduced. Two types of acute heart failure were examined in domestic pigs (Sus scrofa domestica ): a hypoxic model (n=5) with continuous perfusion of the left coronary artery by hypoxic deoxygenated blood and ischemic model (n=9) with proximal closure of the left coronary artery and controlled hypoperfusion behind the closure. The aim was a severe, stable heart pump failure defined by hemodynamic parameters changes: a) decrease in cardiac output by at least 50 %; b) decrease in mixed venous blood saturation to under 60 %; c) left ventricular ejection fraction below 25 %; and d) decrease in flow via the carotid arteries at least 50 %. Acute heart failure developed in the first group in one animal with no acute mortality and in the second group in 8 animals with no acute mortality. In the case of ischemic model the cardiac output fell from 6.70±0.89 l/min to 2.89±0.75 l/min. The saturation of the mixed venous blood decreased from 83±2 % to 58±8 %. The left ventricular ejection fraction decreased from 50±8 % to 19±2 %. The flow via the carotid arteries decreased from 337±78 ml/min to 136±59 ml/min (P≤0.001 for all comparisons). The proposed ischemic model is not burdened with acute mortality in the development of heart failure and is suitable for further use in experimental research into extracorporeal circulatory support., S. Lacko, M. Mlček, P. Hála, M. Popková, D. Janák, M. Hrachovina, J. Kudlička, V. Hrachovina, P. Ošťádal, O. Kittnar., and Obsahuje bibliografii