Laplace's Law adapted to a blood vessel with two-phase wall structure

Traditional equations describing the equilibrium wall tension in a blood vessel assume that the wall consists of a solid material, although it is known to have both solid and fluid components. By describing the forces acting on the blood vessel and applying the Starling Hypothesis, a more general equation is derived describing the tension in a blood vessel wall that includes the individual contributions of the fiber and fluid components. Results show that, unlike in Laplace's Law, fiber tension is a function of transmural pressure and the average oncotic pressure within the wall. In cases where the fluid pressure within the wall is sufficiently negative, the vessel becomes unstable and tends toward closure.