PubMed Health⌕ Search

Biomedical subjects

J Vasků

Publications and source records attributed to J Vasků.

At least 37 records · Page 2Linked to original sources
PubMed1988

Surgical aspects of the implantation of a left ventricle assist device.

The authors have summarised their experience with short-term use of a left ventricle assist device (LVAD). Nine experiments were carried out in healthy calves. A polyurethane pump of their own design, placed extracorporeally, was used. Its in-flow cannula was placed in the left atrium, the outflow one in the initial segment of the descending aorta. The LVAD was operated for a period of 5 days. Fourteen days after its disconnection, the animal was sacrificed and both the bypass system and parenchymal organs were examined. No surgical complications were observed during the experiments. Macro- and microscopical pictures showed minor infarctions in the renal tissue which, however, did not impair renal function. The findings in other organs were related to anaesthesia, the operative procedure and way of animal sacrificing. The experiments have proved the safety of the bypass system used over a short period and, consequently, its potential for future clinical application.

Animals↗
PubMed1988

Serum aldosterone studies in 10 calves living for 2-5 months with a total artificial heart (TAH).

A group of 10 experimental calves that lived for 61-147 days with a TAH was used to study serum aldosterone levels by RIA with ALDOCTK-125 CEA Kit (Sorin Biomedica, Italy). The aldosterone levels were plotted against the serum sodium and potassium, body weight, CVP, urinary sodium and potassium and with hematocrit levels. In these experiments, three types of TAH (TNS-BRNO II, VII, and Rostock) were used. The levels of aldosterone were already high before the surgery and during the entire pumping period, which indicates the development of secondary aldosteronism. The study deals with the mechanisms that participate in the development of aldosteronism in each phase of the experiment with the TAH.

Aldosterone↗
PubMed1987

Haemocompatibility of segmented polyurethanes investigated in vivo.

Samples of segmented polyurethanes differing in composition and in surface morphology were introduced into the left ventricles of hearts of goats for 72 h. After removal of the samples, their surface and the surface of the heart endothelium were evaluated visually with respect to the formation of thrombi. Differences in the interaction of the individual polyurethanes with blood were examined by XPS photoelectron spectroscopy, SEM, and by infrared (i.r.) reflexion spectroscopy. The results suggest ways for improving the haemocompatibility of the surfaces of polyurethanes used as parts of the total artificial heart.

Animals↗
PubMed1987

Calcification of the driving diaphragm in a total artificial heart.

The implications of mineralization on the diaphragm of a TAH were highlighted. The problem was discussed from the point of view of time and site of calcifying deposit formation, and individual patterns of calcification as well as the question of the relationship between mineralization processes and thrombogenicity were considered. Attention was likewise given to actual calcification with regard to its mechanism, and to the risks that the calcification process in an artificial heart pose to the organism. Next, the options to prevent mineralization were reviewed. The issue as analysed especially on the basis of results obtained in the Centre of the State Research project called "Assistance and Replacement of the Heart", Regional Institute of National Health in Brno, Department of Pathological Physiology. It was pointed out that diaphragm calcification can compromise the life of an individual after many years of surviving with an artificial heart. Still, the risk is zero within the first two or three months following artificial heart implantation. The fact was underlined that the last model of a Czechoslovak-made artificial heart, called TNS Brno VII, re-designed in an effort to prevent the breaking away of calcified microemboli from the diaphragm, features optimal athrombogenity. Thus, the clinical version of this brand-new Czechoslovak TAH can be regarded as the best model of an artificial heart to be implanted as a life-saving measure tiding the patient over a period before a cardiac transplantation can be performed.

Animals↗
PubMed1986

Control and driving of pneumatic total artificial hearts TNS-BRNO-II and -III in long-term experiments.

Hemodynamic analysis was carried out during long-term experiments with the pneumatic total artificial hearts TNS-BRNO-II and TNS-BRNO-III to determine standard methods of starting artificial hearts and criteria for their long-term operation in vivo. In long-term experiments, regulatory mechanisms automatically regulating the systole length and diastolic aspiration pressure have also been verified. Comparison of hemodynamic variables obtained from invasive measurements with pneumatic pressure curves permitted the control and monitoring of the experiment in its entirety by noninvasive methods only. The control of the artificial heart using the Chirasist TN 3 and Chirasist TN 4 was adapted to specific properties of the pumps, above all to the functions of the atypical inlet valves. The terminal stages of the experiments have shown that a 100-ml pump can ensure survival of experimental calves up to 210 kg body weight.

Animals↗
PubMed1986

[Comparative study on myocardial damage in irradiated for a long time and nonirradiated rats after administration of FCOL].

The trials were made to assess the effect of FCOL (9-alpha-fluorocortisol + Na2HPO4) and the effect of K and Mg asparaginates and their mixtures on the modifications of Ca2+, Na+, and K+ ions and of the K/Na ratio in the myocardium of rats not irradiated or submitted to permanent whole-body irradiation (gamma irradiation with 0.57 Gy per day during 25 days, total accumulated dose 14.25 Gy; the trials were performed 25 days after the irradiation). The totality of reversible and irreversible functional modifications of the myocardium, expressed by the quantitative assessment of the K/Na ratio and the concentration of Ca2+ ions, was evaluated in order to determine the cardiotoxicity or cardioprotection. It was demonstrated that irradiation alone causes a slight irreversible modification in the myocardium which is not found in non-irradiated rats. FCOL itself increases the rate of Ca2+ and Na+ ions in irradiated and non-irradiated rats, but does not influence the quantity of K+ ions. Severe irreversible myocardial damages are caused by FCOL, but these damages are considerably lower in irradiated rats. Neither in irradiated nor in non-irradiated rats, the isomers of Mg asparaginate show any protective action against the cardiotoxic effect of FCOL. The isomers of K asparaginate, also combined with Mg asparaginates, as well as the preparation Inzolen exert a demonstrable protective effect against myocardial ion modifications following to application of FCOL. The protection is more efficient in irradiated rats.

Animals↗
PubMed1986

Hematological and biochemical studies in calves living over 100 days with the polymethylmethacrylate total artificial heart TNS Brno II.

A polymethylmethacrylate total artificial heart (kinetic components made of polyetherurethane) of TNS Brno II type was implanted into seven calves (2-5 months of age) surviving for the average of 152.4 +/- 19.1 days after the implantation. During the entire post-operative period the animals received oral warfarin-sodium, acetylsalicylic acid, dipyridamole and alpha-tocopherol. Blood was taken for biochemical and hematological examinations twice a week from the jugular vein. During the experiments there were decreases in the number of red blood cells, hematocrit and hemoglobin levels. Plasma free hemoglobin and serum enzymes (alkaline phosphatase, AST, ALT, LDH) increased. Coagulation tests were abnormal because anticoagulation therapy was used. There were minimal changes in the number of white blood cells and platelets, fibrinogen, blood pH, blood glucose, serum electrolytes, bilirubin (total and direct), creatinine, blood urea, and lactate. Possible reasons for observed changes include the gradual rise in the central venous pressure and damaged function of the liver parenchyma. Other factors playing a possible role in inducing changes in laboratory findings are also discussed.

Animals↗
PubMed1985

Innervation of atrial stumps in calves living with the TNS-Brno II artificial heart.

The remnant stumps of the atria in six calves surviving with the artificial TNS-Brno II methacrylate heart for up to 5 months were examined by means of the Bodian silver-impregnating technique and by the formalin-induced fluorescence technique visualizing noradrenaline in monoaminergic nerve terminals. The degeneration of the nerve terminal system detected in animals surviving for 2 days and 1 week was followed by regeneration of the vegetative nerve system in four animals surviving for greater than 1 month. Moreover, thick myelinated nerves afferent in character were detected within the atrium of one animal surviving for 5 months.

Animals↗
PubMed1984

Mechanisms causing the death of 8 calves surviving with implanted artificial heart from 31 to 173 days.

Causes of the death of four animals from the total of eight were technical failures (diaphragm perforations, disconnection of the quick-connector, and a failure of the supply of electric current which could not be prevented). Causes of the death of the remaining four animals were embolisation in the brain stem, embolisation in the superior mesenteric artery leading to diffuse peritonitis, ruptures of aorta and hemocoagulation disorder causing fatal gastrointestinal bleeding.

Animals↗