<p>Right ventricular (RV) dysfunction due to pulmonary and tricuspid valve regurgitation remains understudied despite its critical role in adverse cardiac outcomes. We present a biventricular computational model that integrates regurgitant valves in the RV with a kinematic growth framework. Updated reference configurations are used to allow saturated growth in each growth cycle. Acute regurgitation scenarios and long-term adaptation are modelled to quantify structural and functional adaptations in the RV and their further impacts on left ventricular (LV) performance. Results demonstrate that persistent regurgitation drives dominant eccentric growth in the RV, leading to severe cavity dilation, septal displacement, and impaired LV filling and systolic function. Simulations incorporating both eccentric and concentric growth reveal a limited compensatory role for concentric thickening, even under severe volume overload. The simulated haemodynamic and functional responses are broadly consistent with clinical observations and capture clinically plausible trajectories of RV growth under sustained regurgitation. These findings suggest that biomechanical modelling of myocardial adaptation could provide mechanistic insights into RV adaptation under severe valve regurgitation, and may support clinical decision-making regarding RV failure once fully validated. Future work should focus on validating myocardial growth laws using experimental and clinical data, and extending the framework to patient-specific scenarios for predictive modelling of RV dysfunction due to valve regurgitation.</p>