Cor Triatriatum Sinister: Histopathologic Remarks
To the Editor:
Eichholz and colleagues1 have reported an interesting case of cor triatriatum sinister in an adult. In their article, as in others on the same subject, histopathologic characteristics of the membrane excised from the atrium are not reported. Here, we would like to report a similar case, one followed by a histopathologic study.
We operated on a 19-year-old woman for cor triatriatum sinister, subtype A2 according to the Lam classification. The surgical procedure consisted of excising the typical fenestrated diaphragm from the left atrium. The mitral valve, which appeared to be mildly thickened and stiff without apparent incompetence on saline testing, was excised and replaced. Of note, histologic study revealed a completely altered structure of the mitral valve: its principal layers—the spongiosa, fibrosa, and atrialis/ventricularis—appeared to have been replaced by a homogeneous fibrous tissue, with fibro-blasts and with no elastic component. The endocardial sheet was almost absent. The membrane excised from the left atrium had the same histologic appearance.
Rare observations of mitral pathologic conditions concomitant to cor triatriatum sinister include myxomatous degeneration, hypoplasia, and atresia.2–4 Our experience, although limited to a single case, suggests that alterations of the mitral valve can be associated with other congenital anomalies of the left atrium. Accordingly, when congenital anomalies such as cor triatriatum are discovered in adults, a careful search should be performed for a concomitant pathologic condition that might predispose the mitral valve to subsequent malfunction. This investigation can be achieved with use of modern imaging tools, such as real-time 3-dimensional transesophageal echocardiography and cardiac magnetic resonance.
