Analysis of homeostatic biomechanical thresholds in a left ventricular model of growth and remodelling

Biomechanical models of myocardial growth and remodelling (G&R) are often modelled as responses to deviations from a preferred biomechanical homeostatic state, triggered by stretch or stress. Yet how these critical values of stretch and stress should be defined remains unresolved. This study examines how different homeostatic threshold definitions influence predicted left ventricular G&R. Myocardial growth was implemented using an updated-reference constrained mixture framework, with eccentric growth driven by diastolic myofibre stretch and concentric growth driven by systolic active stress. Homeostatic thresholds were derived from the baseline LV dynamics. Our results demonstrate that the choice of critical homeostatic thresholds plays an important role in triggering cardiac G&R. For volume overload, the mean and 50th percentile end-diastolic myofibre stretch show the potential to approach a preferred mechanical state with preserved cardiac pump function. For pressure overload, a 90th percentile threshold of peak active stress appears to normalise systolic stress to baseline levels with sufficient cardiac output. Localised thresholds generally lead to more heterogeneous growth patterns and potentially high stretch/stress concentrations. These findings highlight the importance of defining homeostatic targets as tissue-level quantities and provide practical guidance to improve cardiac G&R modelling.