COMPLIANCE CHANGES IN PHYSIOLOGICAL AND PATHOLOGICAL STATES

Aim: Although arterial compliance has been estimated by a variety of methods none of them can be directly validated because it is difficult to measure arterial volume. Moreover, because arterial pressure-volume relationships are non-linear, compliance is pressure-dependent. We have developed a method of estimating arterial compliance based on the Windkessel model of the arterial system that can account for the pressure-dependence of compliance. Results: Compared to normotensive humans, compliance was decreased in hypertension and normalized with alpha-blockade, angiotensin converting enzyme inhibition and vasodilators, but not with beta-blockade. Compliance changes with aging, exercise and some diseases were determined. Conclusion: The decreased compliance seen in hypertension was due to an intrinsic change in the arterial wall, most likely due to increased smooth muscle tone.