We read the interesting paper by Freeman et al. [1998] on the prevalence and types of congenital heart disease (CHD) in individuals with Down syndrome. Among 100 patients with trisomy 21 and CHD the authors, using an anatomical classification, reported 45 cases of atrioventricular septal defect (AVSD) and 35 of ventricular septal defect (VSD). Surprisingly, these data are obtained including seven cases of inlet VSD in the group of partial AVSD, probably following an embryological hypothesis.
We disagree with this approach. VSD is a morphologically and morphogenetically variable CHD, including perimembranous, muscular, and subarterial types localized in the inlet, trabecular, or outlet portion of the ventricular septum . In particular, inlet VSD may be perimembranous or muscular . Perimembranous inlet VSD may be associated with cleft of the mitral valve, is prevalent in patients with Down syndrome [Marino et al., 1990a, and should be considered, from the embryogenetic point of view, in the group of "endocardial cushion defects" . However, in the absence of an ostium primum atrial septal defect, this type of VSD is not a partial AVSD [Marino et al., 1990b] as suggested by , but, from the anatomic point of view, must be classified in the group of VSD [Park et al., 1977;.
Similarly, the perimembranous malalignment VSD is associated with DiGeorge/velocardiofacial syndrome , and from the embryogenetic point of view, should be considered a conotruncal anomaly. However, in the absence of infundibular pulmonary stenosis it is not a tetralogy of Fallot, and from the anatomic point of view it must be classified in the group of VSD [Soto et al., 1980].
In reporting CHD associated with genetic syndromes, we suggest an accurate anatomic description of types and subtypes of the anomalies and of the pres-ence of additional heart defects . Moreover, it is useful to clarify which kind of classification is used (embryological or anatomical) and to keep them separate.