The Experts below are selected from a list of 47118 Experts worldwide ranked by ideXlab platform
Gus J Vlahakes - One of the best experts on this subject based on the ideXlab platform.
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determinants of maximal right ventricular function role of septal shift
The Journal of Thoracic and Cardiovascular Surgery, 2002Co-Authors: Uwe P Klima, Luis J Guerrero, Paul J Laraia, Robert A Levine, Gus J VlahakesAbstract:Abstract Background: Right Heart failure can occur after orthotopic Heart transplantation and can complicate implantation of left ventricular assist devices. The functional codeterminants of right ventricular function are not fully understood. We investigated the effects of left ventricular preload and afterload, systemic pressure, and the contribution of the interventricular septum to right ventricular function. Methods and Results: In vivo studies were conducted in 12 dogs by using a highly defined, isovolumic right Heart preparation. At any given arterial pressure, maximal right ventricular developed pressure was not influenced by left Heart Output; however, right ventricular volumes at which peak right ventricular developed pressure occurred differed significantly between the volume-loaded versus the unloaded left ventricle ( P P Conclusions: Right ventricular function has multiple determinants, including the right ventricular free wall, the left ventricle, and the interventricular septum. Changes in right ventricular performance caused by alterations in left ventricular volume load and mean arterial pressure are mediated partially through the interventricular septum, as well as through perfusion of the right ventricular free wall; inactivation of the interventricular septum leads to a significant decrease in right ventricular function. Maintaining left ventricular developed pressure and hence the contribution of the interventricular septum to right ventricular function may be important in the management of right ventricular failure.
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a new biventricular working heterotopic Heart transplant model anatomic and physiologic considerations
Transplantation, 1997Co-Authors: U Klima, Robert A Levine, J L Guerrero, Gus J VlahakesAbstract:BACKGROUND: Current heterotopic Heart transplant models have nonworking left ventricles that atrophy and are not suitable for some studies. We developed and characterized a new heterotopic model with working left and right ventricles. METHODS: Hemodynamics were compared in the working and nonworking models. The influence of the length of the donor's aorta on coronary arterial oxygenation was tested. The influence of the recipient's arterial pressure on developed left ventricular systolic pressure and the effects of alpha- and beta-adrenergic stimulation were examined in both models. The nonworking and working models were compared in chronic transplant preparations to investigate possible ventricular atrophy. RESULTS: In this model, coronary arterial oxygen tension was influenced by the length of the donor's aorta. With a short donor aorta (0.5 cm in the porcine model), normal coronary arterial oxygenation is maintained. Left ventricular systolic pressure was greater in the working compared with the nonworking models. Left ventricular systolic pressure did not respond to alpha-adrenergic stimulation but did respond to beta-adrenergic and combined stimulation, which indicates its relationship to donor Heart Output. Left ventricular systolic pressure correlated with and was determined by recipient arterial pressure. Ventricular atrophy occurred in the nonworking model, but ventricular weight was maintained at sham control levels in this new working model. CONCLUSION: These results demonstrate the surgical anatomic considerations of a new heterotopic Heart transplant model in which the left and right ventricles work. Its hemodynamic performance is related to recipient hemodynamics, and the model responds to adrenergic stimulation. In chronic studies, ventricular mass is maintained, thus allowing this model to overcome a significant shortcoming of existing heterotopic Heart transplant models.
Daniel Burkhoff - One of the best experts on this subject based on the ideXlab platform.
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hemodynamic effects of partial ventricular support in chronic Heart failure results of simulation validated with in vivo data
The Journal of Thoracic and Cardiovascular Surgery, 2007Co-Authors: Deborah Morley, Kenneth N Litwak, Paul Ferber, Paul A Spence, Robert D Dowling, Bart Meyns, Bartley P Griffith, Daniel BurkhoffAbstract:Objective Current left ventricular assist devices are designed to provide full hemodynamic support for patients with end-stage failing Hearts, but their use has been limited by operative risks, low reliability, and device-related morbidity. Such concerns have resulted in minimum use of left ventricular assist devices for destination therapy. We hypothesize that partial circulatory support, which could be achieved with small pumps implanted with less-invasive procedures, might expand the role of circulatory support devices for treatment of Heart failure. Methods We examine the hemodynamic effects of partial left ventricular support using a previously described computational model of the cardiovascular system. Results from simulations were validated by comparison with an in vivo hemodynamic study. Results Simulations demonstrated that partial support (2-3 L/min) increased total cardiac Output (left ventricular assist device Output plus native Heart Output) by more than 1 L/min and decreased left ventricular end-diastolic pressure by 7 to 10 mm Hg with moderate-to-severe Heart failure. Analyses showed that the hemodynamic benefits of increased cardiac Output and decreased left ventricular end-diastolic pressure are greater in less-dilated and less-dysfunctional Hearts. Both the relationships between ventricular assist device flow and cardiac Output and ventricular assist device flow and left atrial pressure predicted by the model closely approximated the same relationships obtained during hemodynamic study in a bovine Heart failure model. Conclusions Results suggest that a pump with a flow rate of 2 to 3 L/min could meaningfully affect cardiac Output and blood pressure in patients with advanced compensated Heart failure. The development of small devices capable of high reliability and minimal complications that can be implanted with less-invasive techniques is supported by these findings.
Robert A Levine - One of the best experts on this subject based on the ideXlab platform.
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determinants of maximal right ventricular function role of septal shift
The Journal of Thoracic and Cardiovascular Surgery, 2002Co-Authors: Uwe P Klima, Luis J Guerrero, Paul J Laraia, Robert A Levine, Gus J VlahakesAbstract:Abstract Background: Right Heart failure can occur after orthotopic Heart transplantation and can complicate implantation of left ventricular assist devices. The functional codeterminants of right ventricular function are not fully understood. We investigated the effects of left ventricular preload and afterload, systemic pressure, and the contribution of the interventricular septum to right ventricular function. Methods and Results: In vivo studies were conducted in 12 dogs by using a highly defined, isovolumic right Heart preparation. At any given arterial pressure, maximal right ventricular developed pressure was not influenced by left Heart Output; however, right ventricular volumes at which peak right ventricular developed pressure occurred differed significantly between the volume-loaded versus the unloaded left ventricle ( P P Conclusions: Right ventricular function has multiple determinants, including the right ventricular free wall, the left ventricle, and the interventricular septum. Changes in right ventricular performance caused by alterations in left ventricular volume load and mean arterial pressure are mediated partially through the interventricular septum, as well as through perfusion of the right ventricular free wall; inactivation of the interventricular septum leads to a significant decrease in right ventricular function. Maintaining left ventricular developed pressure and hence the contribution of the interventricular septum to right ventricular function may be important in the management of right ventricular failure.
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a new biventricular working heterotopic Heart transplant model anatomic and physiologic considerations
Transplantation, 1997Co-Authors: U Klima, Robert A Levine, J L Guerrero, Gus J VlahakesAbstract:BACKGROUND: Current heterotopic Heart transplant models have nonworking left ventricles that atrophy and are not suitable for some studies. We developed and characterized a new heterotopic model with working left and right ventricles. METHODS: Hemodynamics were compared in the working and nonworking models. The influence of the length of the donor's aorta on coronary arterial oxygenation was tested. The influence of the recipient's arterial pressure on developed left ventricular systolic pressure and the effects of alpha- and beta-adrenergic stimulation were examined in both models. The nonworking and working models were compared in chronic transplant preparations to investigate possible ventricular atrophy. RESULTS: In this model, coronary arterial oxygen tension was influenced by the length of the donor's aorta. With a short donor aorta (0.5 cm in the porcine model), normal coronary arterial oxygenation is maintained. Left ventricular systolic pressure was greater in the working compared with the nonworking models. Left ventricular systolic pressure did not respond to alpha-adrenergic stimulation but did respond to beta-adrenergic and combined stimulation, which indicates its relationship to donor Heart Output. Left ventricular systolic pressure correlated with and was determined by recipient arterial pressure. Ventricular atrophy occurred in the nonworking model, but ventricular weight was maintained at sham control levels in this new working model. CONCLUSION: These results demonstrate the surgical anatomic considerations of a new heterotopic Heart transplant model in which the left and right ventricles work. Its hemodynamic performance is related to recipient hemodynamics, and the model responds to adrenergic stimulation. In chronic studies, ventricular mass is maintained, thus allowing this model to overcome a significant shortcoming of existing heterotopic Heart transplant models.
Huang Yi-don - One of the best experts on this subject based on the ideXlab platform.
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Surgery treatment of severe cardiac valve diseases
Chinese Journal of Primary Medicine and Pharmacy, 2005Co-Authors: Huang Yi-donAbstract:Objective In order to improve the cure rate of surgery treatment of severe cardiac valve diseases.Methods A retrospective study was carried out review experience.78 cases of severe cardiac valve diseases receivered the cardiac valve replacement from September 1999 to October 2004.Their perioperative management and myocardial protection and operation were reviewed.Results 62 cases were recovered well.Coplication were seen in 16 cases:low-Heart Output sydrome in 5,re-operation for mediastinal hemorrhage in 3,cerebral infarction in 2,delayed-Heart corruption in 1,renal insufficiency in 1,pulmoanary infection in 1,3 of 16 cases were death.Conclusion Perioperative management and myocardial protection are emphasized.Warm blood-oxgenative myocardioplegia solution is carried out.Bileaflets mechanical Heart valve is used in patients with huge Hearts and small left ventricular in way of retention of left atrioventricular tendon and papillary muscle.Assistant respiration is longed after operation.The patients with severe valve diseases recovery well at eary-staged period.
He Y - One of the best experts on this subject based on the ideXlab platform.
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Perioperative management of severe cardiac valve diseases
Chinese Journal of Primary Medicine and Pharmacy, 2005Co-Authors: He YAbstract:Objective In order to improve t he cure rate of surgery treatment of severe cardiac valve diseases.Metho ds 78 cases of severe cardiac valve diseases had receiveed the cardiac vavle replacement from September 1999 to October 2004 were studied retrospective ly.Perioperative management and myocardial protection were emphasized.Surgery me thods also were reviewed.Results Low-Heart Output sydrome in 5 ,re-operation for mediastinal hemorrage in 3,cerebral infarction in 2,delayed- Heart corruption in 1,renal insufficiency in 1,pulmoanary infecion in 1,death in 3.Conclusion Perioperative management and myocardial protectio n were emphasized.Complete correction of cardiac valve abnormality and the selec tion of artificial Heart valve are important,the patients with severe valve dise ases can recoverly well at early-staged period.
