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Biomedical subjects

D Behrend

Publications and source records attributed to D Behrend.

42 records · Page 3Linked to original sources
PubMed1987

[Filling behavior of pneumatically driven artificial ventricles of the membrane type in vitro].

The filling behaviour of pneumatically driven artificial hearts is an essential determinant of its pumping function. The artificial ventricles developed in Rostock were investigated by means of a hydraulic circulation model for analysis of the influence of different parameters on the filling time. The filling rate is decided by the flow resistance of the inlet valve. Additional resistances are given by the rigidity of the membrane and the flow resistances of the drive line and the drive.

Heart, Artificial↗
PubMed1987

[Experimental testing of the left-ventricular and biventricular assistant systems in dogs].

The left-ventricular (LVAD) and bi-ventricular assistant system (BVAD) were tested in dogs. Our hitherto existing experiences give information specially for the indication of LVAD and BVAD. The risk of a belated application of the LVAD exists in case of only a clinical control by pressure parameters for the degree of a cardiac insufficiency caused by coronary starvations. An aortic pressure of nearly 150/70 mm Hg could be reached by means BVAD on condition of heart fibrillation and a left-atrial pressure of 20 mm Hg. The aortic pressure and the left-atrial pressure decrease drastically after disconnection of the BVAD and these attain the initial values again very promptly after a new connection with the BVAD.

Animals↗
PubMed1986

[Pressure measurements of pneumatically driven artificial ventricles].

In the mock circulation are investigated methods for pressure measurement developed especially for the application on artificial ventricles. They require the in-vivo-confirmation in the long-term experiment. An exact analysis of the pressure curves gives information about the absolute measuring values and also about the function of the pump itself, such as about the points of reaching the final positions of the pump membrane. Via a control related to this in the "full stroke" mode with ejection of the complete stroke volume, when the stand-still times of the membrane are minimized, in addition to this the atrial pressures and the cardiac output can be determined. Eventual non-linearities in the lower pressure region (less than or equal to 0.5 kPa) are not essential in the measurement of the ventricular pressure with amplitudes of 20-25 kPa on the left side and are not investigated in detail.

Assisted Circulation↗
PubMed1984

[Animal experiments using the left-ventricular-assist system].

The left ventricular assist device (LVAD) was tested in 27 sternotomied dogs using hemodynamic parameters. The left ventricular failure was attained by the starvation of the coronary vessels. The use of cannulae and ventriculi fitting for the size of the animals, and a diastolic vacuum were an essential premise for an effective support of the left heart. By variation of the latent period, the systole duration, and the operating pressures were selected for optimal pumping conditions. The effectiveness of the LVAD was shown by the detected pressure and flow parameters.

Animals↗
PubMedDate not supplied

[Polyurethane or silicone as long-term implant substance--a critical evaluation].

Long-term implants made from thermoplastic elastomers have a long history of clinical use. Among other rubber materials, such as polyolefin rubber, much of the demand for rubber-like biomaterials is met by silicone and polyurethane elastomers. The last two elastomers both have sufficient biocompatibility for long-term applications, but differ in terms of biodegradability. Inadequate resistance to degradation almost always leads to implant function loss, which may even threaten the patient's life. Long-term implantation studies in the rat show different mechanisms of biodegradation for polyurethane and silicone. Polyurethane shown deep fissures in the surface, compared with erosion of silicone surfaces. Mechanical and electrical parameters determined to evaluate degradation, additionally show differences in the extent of damage occurring.

Animals↗