Evaluation of Loss of Intimal Compliance on Resistance to Flow in the Common Carotid Artery

摘要

Much attention has focused in the past on the relationship between resistance to the flow of blood and vascular distensibility. In addition to the importance of vascular distensibility and its influence on internal diameter, flow resistance might also be altered by a compliant effect from the soft intimal lining. This compliant effect could be characterized by an ability of the arterial wall to change in thickness under varying conditions of blood volume and pressure, thus altering the internal geometry of the vessel and possibly damping out velocity fluctuations in the blood. The damping out of these velocity fluctuations would then add to the reduction in flow resistance. Based upon these considerations, we inquired whether a physiological analogy to this compliant-surface effect exists in the wall of an artery. An attempt was made to evaluate the role of the soft intimal lining in providing a more efficient vessel for pulsatile flow, since pathological stiffening of the arterial wall is associated with an increased resistance to flow in man. Pressure drop measurements made on the canine common carotid artery encased in hard plastic indicated no significant difference in resistance to flow between the normal internal lining and the artificially hardened intima. It appears that the compliant-surface effect does not occur during laminar pulsatile flow in large arteries.