Histological impairment of the mitral valve in an adult patient affected by cor triatriatum sinistrum

In the case of cor triatriatum, as in other congenital abnormalities, especially if discovered in adult age, concomitant pathology of the cardiac valves should be carefully investigated. This demands an adequate pre-operative study, today possible with the modern imaging techniques. Here, we report a 19-year-old woman operated for a cor tiatriatum sinister; the typical fenestrated diaphragm was excised from the left atrium. The mitral valve, characterized by a moderate-to-severe incompetence, was also excised and substituted. The histological examination revealed an altered valve structure: All its layers were completely replaced by homogeneous fibrous tissue. The atrial diaphragm showed the same histological features. About the pathogenesis of this complex disease, involving different components of the left atrium, we can suppose a unique congenital aetiology.