Mitral valve replacement for small pediatric patients is technically difficult because of the small annulus and requires some technical ideas. The chimney technique is useful for supra-annular mitral valve replacement. We describe a paediatric case of early re-replacement owing to pannus formation after mitral valve replacement using the chimney technique.

Endocarditis due to group B streptococcus is very rare in infants, and may be associated with significant morbidity and mortality. Review of the literature reveals only a single reported case of an infant with this type of streptococcal endocarditis involving the mitral valve. This infant had underlying congenital heart disease, and died shortly after catheterization. We now report group B streptococcal endocarditis occurring in an infant with a structurally normal heart who was treated successfully by replacement of the mitral valve.

A child with pseudoxanthoma elasticum had mitral valvar prolapse with severe regurgitation necessitating replacement with a prosthetic valve. Extensive formation of pannus caused obstruction of two mechanical valves, one after twenty months and the second after three years. Histology of the pannus was similar to the endocardial lesions that are considered unique to pseudoxanthoma elasticum.

A boy with familial eosinophilia had the hypereosinophilic syndrome, with involvement of mitral and tricuspid valves. Between the ages of 11 and 20 years, he underwent eight surgical procedures on his atrioventricular valves. The pathology included recurrent thrombotic vegetative masses related to hypereosinophilia. Initial repair of the mitral valve was shortlived, but recurrent repairs of the tricuspid valve were helpful. Mechanical prostheses inserted in the mitral position thrombosed despite anticoagulant therapy, and bioprosthetic valves deteriorated with thrombus, fibrosis, or tearing. The hypereosinophilic syndrome is unusual in children, and produces additional problems with valvar surgery.

Patients undergoing mitral valve surgery are at risk of left ventricular failure in the immediate post-operative period. In order to understand better the mechanisms of post-operative haemodynamic instability, we used transoesophageal echocardiography to assess the immediate response of the left ventricle to mitral valve replacement for mitral regurgitation or stenosis. A decrease in left ventricular preload, despite adequate filling pressures, was common to both groups and suggests the presence of diastolic dysfunction. A marked impairment in global systolic pump function was observed only in the regurgitation group and correlated with the left ventricular afterload. Transoesophageal echocardiography provides valuable information on the individual changes in left ventricular function and its determinants after mitral valve replacement that are not reflected by haemodynamic measurements.