Wall Properties of Veins

After a brief review of the venous wall structure, the physical properties of veins are discussed in terms of their stress-strain relationships. In contrast to the high pressure arterial system, the low pressure venous system may exhibit large changes in volume without major pressure changes. Inferences about wall properties and intravascular volume from pressure measurements alone are thus meaningless. Depending upon the interplay between intra- and extravascular forces, the venous cross section may oscillate between complete collapse and a circular shape. The stress-strain relationships are both nonlinear and time dependent. Comparative data are given for representative arteries and veins and the distribution of blood volume within the peripheral vasculature is discussed. Finally, some of the venomotor agents and their effects upon stress-strain relations are reviewed.