RESUMO
En cinco capítulos detallan aspectos de la vida de Houssay y de su intercambio epistolar con F P Ludueña, A C Taquini, O Orías y J C Fasciolo, mientras se perfeccionaban en el exterior. El lector descubrirá el manejo inflexible que hizo de los fondos destinados a los gastos de becas, el seguimiento sistemático de las actividades de los beneficiados, la exigencia para que adquirieran conocimientos sobre nuevas tecnologías y el afecto respetuoso que les brindó. Con acierto destacan que Houssay fue un autodidacta, que no se favoreció de becas ni pasantías en centros de fama internacional, pero que comprendió que el envío de becarios postdoctorales al extranjero y su oportuna reinserción en el país era imprescindible parea desarrollar la ciencia autóctona. (AU)
Assuntos
História da Medicina , Médicos/história , Ciência/história , Educação , Bolsas de Estudo/história , ArgentinaRESUMO
Intra-aortic balloon pumping (IABP) could modify the arterial biomechanics; however, its effects on arterial wall properties have not been fully explored. This dynamical study was designed to characterize the pressure-dependent and smooth muscle-dependent effects of IABP on aortic wall energetics in an in vivo animal model. Intra-aortic balloon pumping (1:2) was performed in six anesthetized sheep in which aortic pressure and diameter signals were measured in basal, augmented (during balloon inflation), and assisted (postaugmented) beats. Energy dissipation values in augmented and assisted beats were significantly higher than those observed in basal state (p < 0.05). Assisted beats showed a significant increase of wall damping with respect to basal and augmented beats (p < 0.05). Intra-aortic balloon pumping resulted in a significant increase of pulse wave velocity (p < 0.05) in augmented beats with respect to basal state (6.3 +/- 0.8 vs. 5.2 +/- 0.5 m x s(-1)); whereas values observed in assisted beats were significantly (p < 0.05) lower than those observed in augmented beats (4.9 +/- 0.5 vs. 6.3 +/- 0.8 m x s(-1)). Our findings show that IABP determined the pressure and smooth muscle-dependent changes in arterial wall energetics and damping properties in this animal model.
Assuntos
Aorta/patologia , Contrapulsação , Balão Intra-Aórtico , Animais , Aorta/anatomia & histologia , Débito Cardíaco , Cardiologia/métodos , Circulação Coronária , Vasos Coronários/patologia , Modelos Animais de Doenças , Insuficiência Cardíaca/terapia , Frequência Cardíaca , Modelos Biológicos , Pressão , Ovinos , Fatores de TempoRESUMO
Aortic counterpulsation is a useful technique frequently used in postcardiotomy heart failure. An acute heart failure model in open chest sheep was chosen to evaluate hemodynamic improvement with a counterpulsation balloon pump in juxta-aortic position. This was achieved with a manufactured Dacron prosthesis and a balloon pump placed between the prosthesis and the aorta. Juxta-aortic balloon pump counterpulsation in acute experimental heart failure resulted in a significant improvement of hemodynamic parameters: increase of cardiac output (from 0.86 +/- 0.04 to 1.29 +/- 0.09 L/min, p < 0.05) and cardiac index (from 0.03 +/- 0.01 to 0.04 +/- 0.01 L/min per kg, p < 0.05), and decrease of systemic vascular resistance (from 89.76 +/- 6.69 to 66.56 +/- 6.02 mm Hg/L per min, p < 0.05). The extent of aortic diastolic pressure change evaluated through the diastolic and systolic areas beneath the aortic pressure curve (DABAC/SABAC) index before cardiac failure induction showed a significant increase compared with unassisted values (from 0.81 +/- 0.10 to 1.12 +/- 0.09, p < 0.05). Assisted values of DABAC/SABAC index after heart failure induction also showed a significant increase compared with unassisted values (from 0.78 +/- 0.21 to 1.17 +/- 0.38, p < 0.05). Treatment of experimental acute heart failure by juxta-aortic balloon pump counterpulsation allows an effective hemodynamic improvement in open chest sheep.
Assuntos
Baixo Débito Cardíaco/etiologia , Baixo Débito Cardíaco/terapia , Balão Intra-Aórtico/métodos , Pericardiectomia/efeitos adversos , Complicações Pós-Operatórias , Doença Aguda , Animais , Aorta/fisiopatologia , Prótese Vascular , Baixo Débito Cardíaco/fisiopatologia , Modelos Animais de Doenças , Hemodinâmica/fisiologia , Polietilenotereftalatos/uso terapêutico , OvinosRESUMO
The role of blood viscosity on arterial wall elasticity before and after deendothelization (DE) was studied. Seven ovine brachiocephalic arteries were studied in vitro under physiological pulsatile flow conditions achieved by a mock circulation loop. Instantaneous pressure and diameter signals were assessed in each arterial segment. Incremental elastic modulus (E(inc)) was calculated using the slope of the pure elastic stress-strain relationship. There was no significant difference between E(inc) values before and after DE (3.11 vs. 3.16 10(7) dyn/cm(2)) at a blood viscosity of 2.00 mPa. s. Increases in blood viscosity (2.50, 3.00, 3.50, and 4.00 mPa. s) always resulted in decreases of E(inc) before DE; inversely, increases in blood viscosity resulted in increases of E(inc) after DE. These values of E(inc), for identical levels of blood viscosity, were always significantly lower (P < 0.05) before DE than those obtained after DE. Arterial wall elasticity assessed through E(inc) was strongly influenced by blood viscosity, probably due to presence or absence of endothelium relaxing factors or to direct shear smooth muscle activation when endothelial cells are removed.