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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of interventional cardiology 11 (1998), S. 0 
    ISSN: 1540-8183
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The introduction of minimally invasive techniques represents the most dramatic and controversial new development in cardiac surgery. Almost all minimally invasive surgery involves modified standard incisions and at least partial direct vision of the operative field. Therefore, minimally invasive cardiac surgery is defined as an operation through a smaller than usual incision. The procedures then can be divided into those with or without cardiopulmonary bypass. They can be applied in coronary artery bypass grafting or in valvular operations. Ultimately, almost all cardiac surgery could be performed in a minimally invasive fashion. However, the dominance of any type of procedure will depend on data supporting effectiveness, relative technical ease, ultimate cost savings, and improved patient outcome. Many of these data are lacking or are preliminary. Prospective, randomized comparisons are needed.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1546-170X
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Medicine
    Notes: [Auszug] The adult heart lacks reserve cardiocytes and cannot regenerate. Therefore, a large acute myocardial infarction often develops into congestive heart failure. To attempt to prevent this progression, we transplanted skeletal myoblasts into cryoinfarcted myocardium of the same rabbits (autologous ...
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1546-170X
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Medicine
    Notes: [Auszug] Nature Med. 4, 929– 933, On page 931, Fig. 2a. The symbols within the caption for Fig.2a were switched. Figure 2a is shown to the right and the correct caption is located below. We regret this ...
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1540-8159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The effects of ventricular pacing on left ventricular (LV) dynamic geometry, function, and myocardial oxygen consumption (MVO2) were measured in 12 conscious dogs using sonomicrometry, micromanometry, ultrasonic flow probes, and oximetry catheters during right atrial (A-) and right ventricular (V-) pacing at 150 beats/mm. Systolic function was quantified using slopes (Mw) and volume-intercepts (Vw) of linear relationships between end-di-astolic volume (EDV) and stroke work (SW) for data obtained during vena caval occlusion. V-pacing shifted SW-EDV relationships downward (Mw decreased from 97 ± 21 to 81 ± 21 Kerg/mL) and to the right (Vw increased from 14 ± 11 to 20 ± 12 mL) in comparison with A-pacing (P 〈 0.05). These functional changes correlated with altered contractile geometry manifest as early shortening in the septal free wall relative to anterior-posterior dimension (increased minor axis mid-wall eccentricity at end-diastole and begin-ejection). Steady-state LV power output decreased from 802 ± 213 mW during A-pacing to 514 ± 170 mW during V-pacing (P 〈 0.05), while MVO2 remained relatively unchanged during V-pacing (10 ± 3 mL O2/min vs 11 ± 3 mL O2/min during A-pacing, P = NS). As a result, overall LV efficiency decreased from 0.24 ± 0.08 during A-pacing to 0.16 ± 0.06 during V-pacing (P 〈 0.05). These data illustrate the impact of V-pacing on dynamic LV geometry and function, including impaired LV work output at all physiological levels of preload. Most importantly, the relationship between LV work output and MVO2 is depressed during V-pacing, emphasizing the interaction between LV mechanics and pump efficiency in intact subjects. As a result, measures taken to restore normal contractile geometry might improve LV efficiency and performance when V-pacing is necessary.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1573-9686
    Keywords: Windkessel model ; Total arterial compliance ; Integral method ; Waveform reconstruction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract We developed and validated a new, more accurate, and easily applied method for calculating the parameters of the three-element Windkessel to quantitate arterial properties and to investigate ventriculoarterial coupling. This method is based on integrating the governing differential equation of the three-element Windkessel and solving for arterial compliance. It accounts for the interaction between characteristic impedance and compliance, an important phenomenon that has been ignored by previously implemented methods. The new integral method was compared with four previously published methods as well as a new independent linear least-squares analysis, using ascending aortic micromanometric and volumetric flow measurements from eight dogs. The parameters calculated by the new integral method were found to be significantly different from those obtained by the previous methods but did not differ significantly from maximum likelihood estimators obtained by a linear leastsquares approach. To assess the accuracy of parameter estimation, pressure and flow waveforms were reconstructed in the time domain by numerically solving the governing differential equation of the three-element Windkessel model. Standard deviations of reconstructed waveforms from the experimental ensemble-averaged waveforms, which solely reflect the relative accuracy of the Windkessel parameters given by the various methods, were calculated. The new integral method invariably yielded the smallest error. These results demonstrate the improved accuracy of our new integral method in estimating arterial parameters of the three-element Windkessel.
    Type of Medium: Electronic Resource
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