Aim: The assumption that the arterial wall behaves like incompressible material simplifies the analysis of arterial wall elasticity. Experimental evidence for the incompressibility assumption has been obtained directly by volume-displacement and radiological methods. Recent developments in ultrasound technology have made it possible to take direct, high-resolution measurements of the internal diameter and wall thickness of an artery and thus calculate the cross-sectional area of the arterial wall. The objective of this study was to determine the cross-sectional area of the arterial wall in vitro at different levels of strain in order to demonstrate the incompressibility assumption.
Methods: Two different types of fresh, human, medium-sized arteries were studied, the internal mammary artery, and a less elastic and more muscular artery, the radial artery. The internal diameter and wall thickness were measured with an ultrasonic echo-tracking device (NIUS 1; Asulab, Neuchâtel, Switzerland) over 1-min steps of increasing intra-arterial pressure (0, 50, 100, 150 and 175 mmHg).
Results: The cross-sectional area of the arterial wall of the radial and internal mammary artery remained unchanged under different levels of strain.
Conclusion: Since the artery length remained constant during the pressure increases, the lack of change in the cross-sectional area of the arterial wall suggests that the arterial wall of human medium-sized arteries is essentially incompressible.