THEORETICAL-STUDY OF STRESS-MODULATED GROWTH IN THE AORTA

A theoretical model is presented for stress-modulated growth in the ao rta. The model consists of a pseudoelastic tube composed of two layers representing the intima/media and the adventitia. Finite volumetric g rowth is included by letting the time-rate of change of the zero-stres s dimensions of each volume element depend linearly on the local stres ses. After analysing the model, we examine its fundamental growth resp onse under changes in loads, material properties, and growth parameter s. The behavior of the model is quite sensitive to changes in material nonlinearity and in the coefficients of the growth law. Next, growth of the aorta is simulated during development and maturity. For an appr opriate choice of the parameters, the model exhibits patterns of growt h that agree qualitatively with known characteristics of aortic growth . Comparison of model results with published experimental data during hypertension in the rat shows good agreement in the time course of the vessel radii and residual strain. Finally, the implications of the re sults are discussed in the context of deducing a general mechanical gr owth law for soft tissues. The proposed model should be useful in stud ies to determine the biomechanical factor that regulates growth. (C) 1 996 Academic Press Limited.