Abstract
A previously healthy young man sustained a deceleration chest injury. Severe mitral regurgitation was confirmed by Doppler and cardiac catheterisation. The mitral valve and subvalvular apparatus appeared normal at the subsequent surgery. Papillary muscle dysfunction was considered to be the principal cause of the regurgitation. Mitral-valve repair failed to preserve the competence of the valve, leading to successful mitral-valve replacement. Histology of the papillary muscle showed necrosis, confirming the original diagnosis. Post-traumatic papillary muscle dysfunction is concluded to be one of the causes of severe mitral regurgitation. Appropriate treatment is valve replacement rather than attempting conservative management.