ECHOCARDIOGRAPHIC-MORPHOLOGIC CORRELATIONS IN TRICUSPID-ATRESIA

Objectives. Our aim was to clarify the anatomic substrate in hearts di agnosed as having tricuspid atresia by studying autopsy specimens and comparing the findings with those in two-dimensional echocardiograms. Background. Traditionally, tricuspid atresia was thought, and is still believed by some, to be due to an imperforate valvular membrane inter posed between the floor of the blind ending right atrium and the hypop lastic right ventricle. Others argued that the dimple, when present, p ointed to the outflow tract of the left ventricle rather than to the r ight ventricle, making the lesion more akin to double-inlet left ventr icle. Methods. We examined 39 autopsy specimens catalogued as having t ricuspid atresia. We then studied 24 two dimensional echocardiograms f rom patients,vith a primary diagnosis of tricuspid atresia. Results. O f the 39 specimens, 37 had a completely muscular floor to the right at rium (absent right atrioventricular [AV] connection). The dimple, when identified, was (except in one case) directed to the left ventricular outflow tract. Only two hearts had an imperforate tricuspid valve. Tw o-dimensional echocardiograms grams in all cases showed an echo-dense band, produced by the fibrofatty tissue of the AV groove and represent ing absence of the right AV connection, between the muscular floor of the morphologically right atrium and the ventricular mass. Conclusion. Tricuspid atresia is usually, but not always, due to morphologic abse nce of one AV connection. In most cases, the ventricular mass then com prises a dominant left ventricle together with a rudimentary and incom plete right ventricle.