The Experts below are selected from a list of 67704 Experts worldwide ranked by ideXlab platform
Josef Rösch - One of the best experts on this subject based on the ideXlab platform.
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Aortic and venous valve for percutaneous insertion.
Minimally Invasive Therapy and Allied Technologies, 2000Co-Authors: Dusan Pavcnik, Barry Uchida, Hans A. Timmermans, Frederick S. Keller, Josef RöschAbstract:SummaryThe purpose of this paper is to present in vitro and in vivo experimental evaluation of a new, artificial, bicuspid, aortic and venous valve. Valves were constructed from square stents with barbs covered by porcine small intestine submucosa (SIS). A valve 15 mm in diameter was tested in a flow model (2.5 l/min) with pressure measurement. A 100-ml rubber bag attached to a side arm of the flow model simulated Heart Ejection Fraction. In acute (n=6) and short-term (n=3) experiments conducted in four swine and four dogs, valves ranging from 16 - 28mm in diameter were placed into the ascending aorta through 10 F sheaths; three were placed subcoronary and six in a supracoronary position. Function and stability of the valves were studied with pressure measurements and aortograms. Three short-term animals were sacrificed for gross and histologic evaluation at one, two and four weeks respectively. In an acute experiment, venous valves with four barbs were placed into the IVC through an 8 F guiding catheter ...
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Aortic and venous valve for percutaneous insertion.
Minimally Invasive Therapy & Allied Technologies, 2000Co-Authors: Dusan Pavcnik, Frederick S. Keller, B T Uchida, H Timmermans, C L Corless, Josef RöschAbstract:The purpose of this paper is to present in vitro and in vivo experimental evaluation of a new, artificial, bicuspid, aortic and venous valve. Valves were constructed from square stents with barbs covered by porcine small intestine submucosa (SIS). A valve 15 mm in diameter was tested in a flow model (2.5 l/min) with pressure measurement. A 100-ml rubber bag attached to a side arm of the flow model simulated Heart Ejection Fraction. In acute (n=6) and short-term (n=3) experiments conducted in four swine and four dogs, valves ranging from 16-28 mm in diameter were placed into the ascending aorta through 10 F sheaths; three were placed subcoronary and six in a supracoronary position. Function and stability of the valves were studied with pressure measurements and aortograms. Three short-term animals were sacrificed for gross and histologic evaluation at one, two and four weeks respectively. In an acute experiment, venous valves with four barbs were placed into the IVC through an 8 F guiding catheter in three dogs. For longer-term testing, valves were placed into the IVCs and iliac veins of three young swine. The animals were followed up after two weeks with venograms, then were sacrificed for gross and histologic evaluation.
M Hamdi - One of the best experts on this subject based on the ideXlab platform.
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an inverse finite element method for determining the tissue compressibility of human left ventricular wall during the cardiac cycle
PLOS ONE, 2013Co-Authors: Abdallah I Hassaballah, M A Hassan, Azizi N Mardi, M HamdiAbstract:The determination of the myocardium’s tissue properties is important in constructing functional finite element (FE) models of the human Heart. To obtain accurate properties especially for functional modeling of a Heart, tissue properties have to be determined in vivo. At present, there are only few in vivo methods that can be applied to characterize the internal myocardium tissue mechanics. This work introduced and evaluated an FE inverse method to determine the myocardial tissue compressibility. Specifically, it combined an inverse FE method with the experimentally-measured left ventricular (LV) internal cavity pressure and volume versus time curves. Results indicated that the FE inverse method showed good correlation between LV repolarization and the variations in the myocardium tissue bulk modulus K (K=1/compressibility), as well as provided an ability to describe in vivo human myocardium material behavior. The myocardium bulk modulus can be effectively used as a diagnostic tool of the Heart Ejection Fraction. The model developed is proved to be robust and efficient. It offers a new perspective and means to the study of living-myocardium tissue properties, as it shows the variation of the bulk modulus throughout the cardiac cycle.
H Metzler - One of the best experts on this subject based on the ideXlab platform.
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urapidil reduces elevated pulmonary vascular resistance in patients before Heart transplantation
Journal of Heart and Lung Transplantation, 2002Co-Authors: Michael Zink, H Gombotz, Andrae Wasler, B Grasser, Peter Rehak, H MetzlerAbstract:Abstract Background: Elevated pulmonary vascular resistance is a major limitation for Heart transplantation. Urapidil is a centrally and peripherally acting anti-hypertensive drug, able to decrease elevated pulmonary vascular resistance in patients with either chronic obstructive pulmonary disease or Heart failure. Urapidil is available as an oral or intravenous drug. In this study, we evaluated the possible beneficial effects of intravenous urapidil in patients with reversible, elevated pulmonary vascular resistance who were scheduled for Heart transplantation. Methods: After approval by the Ethics Committee and written consent, 22 consecutive patients with end-stage Heart failure and history of pulmonary vascular resistance >3 Wood units were enrolled into an open, prospective study. Using a (right ventricular Ejection Fraction) REF-Swan-Ganz catheter, hemodynamics were determined during administration of nitric oxide, and before and after 3 repeated intravenous applications of 10 mg urapidil. The treatment goal was reduction of pulmonary vascular resistance by at least 30%. Results: Twenty-two patients were included to obtain complete data for 14 patients. Eight patients were not treated with urapidil: 7 patients had normal pulmonary vascular resistance at baseline, and 1 patient experienced moderate pulmonary edema before the study began. Two patients did not reach the treatment goal. In patients who responded to urapidil, the following hemodynamic changes were observed: decreased pulmonary vascular resistance (−48%), decreased transpulmonary gradient (20.0 to 13.7 mm Hg), decreased mean pulmonary arterial pressure (40 to 31 mm Hg), decreased systemic vascular resistance (−27%), mean arterial pressure (80 to 72 mm Hg), and increased right Heart Ejection Fraction (21% to 27%). Heart rate remained unchanged. Conclusions: Intravenous urapidil lowered elevated pulmonary vascular resistance in patients before Heart transplantation. In comparison with other vasodilative drugs, the major benefit of urapidil is its oral formulation.
Dusan Pavcnik - One of the best experts on this subject based on the ideXlab platform.
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Aortic and venous valve for percutaneous insertion.
Minimally Invasive Therapy and Allied Technologies, 2000Co-Authors: Dusan Pavcnik, Barry Uchida, Hans A. Timmermans, Frederick S. Keller, Josef RöschAbstract:SummaryThe purpose of this paper is to present in vitro and in vivo experimental evaluation of a new, artificial, bicuspid, aortic and venous valve. Valves were constructed from square stents with barbs covered by porcine small intestine submucosa (SIS). A valve 15 mm in diameter was tested in a flow model (2.5 l/min) with pressure measurement. A 100-ml rubber bag attached to a side arm of the flow model simulated Heart Ejection Fraction. In acute (n=6) and short-term (n=3) experiments conducted in four swine and four dogs, valves ranging from 16 - 28mm in diameter were placed into the ascending aorta through 10 F sheaths; three were placed subcoronary and six in a supracoronary position. Function and stability of the valves were studied with pressure measurements and aortograms. Three short-term animals were sacrificed for gross and histologic evaluation at one, two and four weeks respectively. In an acute experiment, venous valves with four barbs were placed into the IVC through an 8 F guiding catheter ...
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Aortic and venous valve for percutaneous insertion.
Minimally Invasive Therapy & Allied Technologies, 2000Co-Authors: Dusan Pavcnik, Frederick S. Keller, B T Uchida, H Timmermans, C L Corless, Josef RöschAbstract:The purpose of this paper is to present in vitro and in vivo experimental evaluation of a new, artificial, bicuspid, aortic and venous valve. Valves were constructed from square stents with barbs covered by porcine small intestine submucosa (SIS). A valve 15 mm in diameter was tested in a flow model (2.5 l/min) with pressure measurement. A 100-ml rubber bag attached to a side arm of the flow model simulated Heart Ejection Fraction. In acute (n=6) and short-term (n=3) experiments conducted in four swine and four dogs, valves ranging from 16-28 mm in diameter were placed into the ascending aorta through 10 F sheaths; three were placed subcoronary and six in a supracoronary position. Function and stability of the valves were studied with pressure measurements and aortograms. Three short-term animals were sacrificed for gross and histologic evaluation at one, two and four weeks respectively. In an acute experiment, venous valves with four barbs were placed into the IVC through an 8 F guiding catheter in three dogs. For longer-term testing, valves were placed into the IVCs and iliac veins of three young swine. The animals were followed up after two weeks with venograms, then were sacrificed for gross and histologic evaluation.
Abdallah I Hassaballah - One of the best experts on this subject based on the ideXlab platform.
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an inverse finite element method for determining the tissue compressibility of human left ventricular wall during the cardiac cycle
PLOS ONE, 2013Co-Authors: Abdallah I Hassaballah, M A Hassan, Azizi N Mardi, M HamdiAbstract:The determination of the myocardium’s tissue properties is important in constructing functional finite element (FE) models of the human Heart. To obtain accurate properties especially for functional modeling of a Heart, tissue properties have to be determined in vivo. At present, there are only few in vivo methods that can be applied to characterize the internal myocardium tissue mechanics. This work introduced and evaluated an FE inverse method to determine the myocardial tissue compressibility. Specifically, it combined an inverse FE method with the experimentally-measured left ventricular (LV) internal cavity pressure and volume versus time curves. Results indicated that the FE inverse method showed good correlation between LV repolarization and the variations in the myocardium tissue bulk modulus K (K=1/compressibility), as well as provided an ability to describe in vivo human myocardium material behavior. The myocardium bulk modulus can be effectively used as a diagnostic tool of the Heart Ejection Fraction. The model developed is proved to be robust and efficient. It offers a new perspective and means to the study of living-myocardium tissue properties, as it shows the variation of the bulk modulus throughout the cardiac cycle.
