A MODEL FOR STRESS-INDUCED GROWTH IN THE DEVELOPING HEART

Mechanical loads affect growth and morphogenesis in the developing hea rt. Using a theoretical model we studied stress-modulated growth in th e embryonic chick ventricle during stages 21-29 (4-6 days of a 21-day incubation period). The model is a thick-walled, compressible, pseudoe lastic cylinder, with finite volumetric growth included by letting the rate of change of the local zero-stress configuration depend linearly on the Cauchy stresses. After investigating the fundamental behavior of the model we used it to study global and focal growth in the primit ive ventricle due to normal and abnormal cavity pressures. With end-di astolic pressure taken as the growth-modulating stimulus, correlating theoretical and available experimental results yielded the coefficient s of the growth law, which was assumed to be independent of time and l oading conditions. For both normal and elevated pressures, the predict ed changes in radius and wall volume during development were similar t o experimental measurements. In addition, the residual stress generate d by differential growth agreed with experimental data. These results suggest that wall stress may be a biomechanical factor that regulates growth in the embryonic heart.