Strategies of the treatment of cardiac prosthetic valve thrombosis

Department of Cardiac Surgery, Republican Hospital, Chisinau, the Republic of MoldovaBackground: The article deals with the analysis of principal causes of valve prosthesis thrombosis and “pannus” thrombosis. The diagnosis and contemporary treatment strategy of prosthesis dysfunction have been considered. Material and methods: In our department 1670 patients with extracorporeal circulation were operated on, among them 1260 had valve pathology that made up 74.2%. 1164 heart valves were replaced, 145 of them were biological prostheses and 1019 were mechanical ones of different types. Prosthesis thrombosis took place in 28 patients that represented 60% of the number of patients with prothesis disfunction and 2.2% of the total number of operated patients from which 21 patients, their age ranged from 35 to 63 years old. The surgical treatment was performed to 9 patients, thrombolysis – to 19 patients. Results: During last 6-7 years the thrombolysis treatment with ateplasum and reteplasse has been successfully implemented in the therapy of thrombosis valve prothesis. Thrombolysis was performed to 19 patients. The results are the following: in 17 cases good outcomes (a complete recovery of the prosthesis function with transprosthetic gradient and the normalization of systolic pressure in right ventricle) have been registered, one case has been complicated with transitory ischemic ictus. Out of 19 patients who underwent the thrombolysis treatment, there were 2 lethal cases. Conclusions: The patients that are in a critical state with prosthesis thrombosis (acute pulmonary edema, hypotension, heart insufficiency NYHA IV) should immediately receive EchoCG confirmation of the need of intravenous thrombolitic therapy. The thrombolysis efficacy in prosthesis thrombosis is high; the rate of embolic complications is low, which can be used as the first line treatment for all patients with prothesis thrombosis (in the absence of contraindications). In the case of partial response to the thrombolysis treatment, the patient can be operated on in good hemodynamic conditions and with low surgical risk

Influence of bias voltage on the microstructure and physical properties of magnetron sputtered Zr–Si–N nanocomposite thin films

e report an investigation concerning the influence of ion bombardment on the nanostructure and physical properties of Zr–Si–N nanocomposite thin films. The films were deposited by reactive magnetron sputtering from individual Zr and Si targets. The Si content was varied by changing the power applied to the Si target. The increase of ion bombardment energy was obtained by applying a negative potential Ub = − 150 V to the substrate. The evolution of the film texture, grain size and lattice constant was mapped out using X-ray diffraction measurements. Zr–Si–N films deposited at a substrate temperature Ts = 510 K with a bias voltage of Ub = − 150 V exhibit less pronounced columnar structure with small crystallites having various orientations. The maximum nanohardness of 39 GPa is reached for the films at about 2.5 at.% Si, 8 nm grain size and 0.3 Si surface coverage. The increased energy of ionic species reaching the substrate when a negative bias voltage is applied seems to have the opposite effect to that of increasing substrate temperature: reduced SiNx coverage on the ZrN nanocrystallites

WC/a-C nanocomposite thin films: Optical and electrical properties

WC/amorphous carbon (a-C) thin films were deposited by dual magnetron sputtering from individual WC and graphite targets. The influence of film composition and microstructure on the optical and electrical properties was investigated. As evidenced by x-ray photoelectron spectroscopy and grazing angle x-ray diffraction measurements, the WC/a-C films are composite materials made of hexagonal W2C and/or cubic beta-WC1-X nanocrystallites embedded in (a-C) matrix. The optical properties were studied by spectroscopic ellipsometry and the electrical resistivity was measured by the van der Pauw method between 20 and 300 K. Both the optical and the electrical properties of the WC/a-C films are correlated with the chemical composition and microstructure evolution caused by a-C addition. The optical properties of W2C/a-C and beta-WC1-x/a-C films with a-C content <= 10 at. % are explained by modeling their dielectric functions by a set of Drude-Lorentz oscillators. Further increase in a-C content leads only to the formation of beta-WC1-x/a-C nanocomposite structures and their optical properties progressively evolve to those of a-C single phase. The electrical resistivity as a function of the temperature of all the films exhibits a negative temperature coefficient of resistivity. Theoretical fitting using the grain-boundary scattering model shows that the transport properties are mainly limited by the grain size and electron mean free path parameters

In hospital cardiac arrest: a role for automatic defibrillation.

INTRODUCTION: Sudden cardiac death (SCD) survival decreases by 10% for each minute of delay in defibrillation, however, survival rates of 98% can be achieved when defibrillation is accomplished within 30s of collapse. Recently, a fully automated external cardioverter-defibrillator (AECD) was approved by the FDA for in-hospital use. The AECD can be programmed to automatically defibrillate when a life threatening ventricular arrhythmia occurs. The purpose of this study was to assess the potential impact of in-hospital AECDs on the critical time to defibrillation in monitored hospital units. METHODS: Mock emergency (n = 18) were conducted using simulated ventricular fibrillation in various monitored units. Observers were stationed to record the time staff responded to the arrhythmia, and the time to shock. These times were compared to an AECD protocol that defibrillates automatically in an average of 38.3 s from onset of arrhythmia (n = 18). RESULTS: Staff versus AECD response time to arrhythmia (s) was 76.3 +/- 113.7 (CI 19.8-132.8) versus 7.6 +/- 0.6 (CI 7.3-7.9). Staff versus AECD time to shock was 169.2 +/- 103.1 (CI 117.9-220.4) versus 38.3 +/- 0.7 (CI 37.9-38.6). P-values are CONCLUSION: The use of AECDs on monitored units would significantly reduce the critical time to defibrillation in patients with SCA. We anticipate this would translate to improved survival rates, and better neurologic outcomes