Mechanics of the Aorta in Vivo: A Radiographic Approach

摘要: The hydraulic properties of the unexposed thoracic aorta were studied in five cats by angiography. Repeated measurements pressure and diameter obtained at various distances from aortic root, it became obvious that was more than twice as distensible exposed aorta. Diameter for example, varied about 20% over a physiologic pulse (40 mm Hg); even lower variations exceeded 15%. When plotted function distance distensibility both decreased, calculated impedance increased. Despite these changes, however, reflection coefficients quite small. It concluded geometric elastic inhomogeneities tend to balance one another, keeping coefficient low helping "decouple" oscillatory left ventricular pump static peripheral vasculature. Since contour is reflection-free during first 50 msec following onset ejection, may reliably indicate their changes with stress. In several animals, norepinephrine infusion used elevate hypertensive levels. compared hypertension induced carotid reflex stimulation or mechanical occlusion aorta, wall essentially same, suggesting this agent has no important direct effect on wall.