[The influence of pressure and temperature on the behavior of the human aorta and carotid arteries]. / Influencia de la presión y la temperatura en el comportamiento de la aorta y las carótidas humanas.

INTRODUCTION AND OBJECTIVES: The thermomechanical behavior of human arteries is still not well characterized despite its importance for understanding arterial physiology, and for evaluating and improving surgical procedures. The aim of this study was to provide, for the first time, experimental data illustrating how the mechanical responses of two types of human artery -the carotid artery and the aorta- are affected by changes in temperature. METHODS: The mechanical properties of the arteries were derived in vitro from internal pressure-external diameter curves measured at four different temperatures (i.e., 17, 27, 37 and 42 degree C). Coefficients of expansion and stiffness were obtained by thermomechanical analysis. The condition of the arterial wall was determined histologically. RESULTS: The aorta and the carotid artery became slightly more compliant as the temperature increased. In both vessels, the coefficient of expansion depended critically on internal pressure. At low pressures, the coefficient of expansion was negative (i.e., the vessel contracted when heated), whereas close to a specific threshold pressure, which is different for each type of artery, the coefficient became positive. CONCLUSIONS: The mechanical behavior of arteries is affected by the combination of internal pressure and temperature. Consequently, the effect of this combination should be taken into account in clinical situations involving a change in temperature. Moreover, the strength of the effect depends on the type of artery under study. As a result, more detailed experimental data focusing on vessels of clinical interest are required.

Influencia de la presión y la temperatura en el comportamiento de la aorta y las carótidas humanas / The influence of pressure and temperature on the behavior of the human aorta and carotid arteries

Introducción y objetivos. La respuesta termomecánica de las arterias humanas es poco conocida a pesar de su importancia para la comprensión de la fisiología arterial, y para la evaluación y mejora de los procedimientos quirúrgicos. El objetivo de este trabajo es aportar por vez primera datos experimentales que muestren cómo se ve afectada la respuesta mecánica de dos tipos de arterias humanas ­aorta y carótida­ por los cambios de temperatura. Métodos. La respuesta mecánica de las arterias se ha obtenido in vitro a través de la medición de las curvas presión interior-diámetro exterior para 4 temperaturas (17, 27, 37 y 42 oC). Se ha realizado un análisis termomecánico para obtener los coeficientes de dilatación y la rigidez del material. El estado de la pared arterial se ha evaluado mediante análisis histológico. Resultados. Las arterias aorta y carótida aumentan ligeramente su flexibilidad con la temperatura. El coeficiente de dilatación de ambos vasos depende críticamente de la presión interior aplicada. A bajas presiones, el coeficiente de dilatación es negativo (el vaso se contrae cuando se calienta), mientras que por encima de cierta presión umbral ­distinta para cada tipo de arteria­ el coeficiente de dilatación se hace positivo. Conclusiones. El efecto combinado de la presión interior y la temperatura afecta al comportamiento de las arterias y, por ello, debe ser tenido en cuenta al abordar situaciones clínicas que impliquen cambios de temperatura. La intensidad de este efecto depende del tipo de arteria estudiada, lo que requiere la obtención de datos más detallados, centrados en los vasos de interés clínico

Introduction and objectives. The thermomechanical behavior of human arteries is still not well characterized despite its importance for understanding arterial physiology, and for evaluating and improving surgical procedures. The aim of this study was to provide, for the first time, experimental data illustrating how the mechanical responses of two types of human artery ­the carotid artery and the aorta­ are affected by changes in temperature. Methods. The mechanical properties of the arteries were derived in vitro from internal pressure­external diameter curves measured at four different temperatures (i.e., 17, 27, 37 and 42 oC). Coefficients of expansion and stiffness were obtained by thermomechanical analysis. The condition of the arterial wall was determined histologically. Results. The aorta and the carotid artery became slightly more compliant as the temperature increased. In both vessels, the coefficient of expansion depended critically on internal pressure. At low pressures, the coefficient of expansion was negative (i.e., the vessel contracted when heated), whereas close to a specific threshold pressure, which is different for each type of artery, the coefficient became positive. Conclusions. The mechanical behavior of arteries is affected by the combination of internal pressure and temperature. Consequently, the effect of this combination should be taken into account in clinical situations involving a change in temperature. Moreover, the strength of the effect depends on the type of artery under study. As a result, more detailed experimental data focusing on vessels of clinical interest are required