A Saw-Tooth Rather Than Noncompacted Variant of Left Ventricular Structure

represent a form of left ventricularnoncompaction (LVNC).Landmark echocardiographic (2) and cardiovascular magneticresonance (3) studies indicate that the diagnosis of LVNC dependson imaging appearances indicative of a relatively thick, noncom-pacted trabecular meshwork with deep endomyocardial recesses.These features were identified in lateral, apical, and mid-inferiorwall regions, but not down the length of the septum in any of thecases studied (2,3).The 4-chamber images provided by Rafiq et al. (1)donotshow evidence of a trabeculated meshwork, but rather severaldistinct protrusions of the apparently compact myocardium ofthe interventricular septum. They thicken in systole and remainclearly demarcated, throughout the cardiac cycle, in a way thatsuggests a through-plane orientation of relatively large-scalemyocardial ridges. In our view, the imaging criteria of LVNCare not met.On the other hand, the images are comparable with a variant ofleft ventricular myocardial structure that has been described in asingle infant by one of us (4). This was characterized as “saw-tooth” because of the coarsely indented endocardial border appar-ent, in that case, along the septal, inferior, and lateral walls inlong-axis views. We therefore propose that the images shown byRafiq et al. (1) also represent a rare form of myocardial dysplasia,different from LVNC but comparable to the case reported byDavlouros et al. (4), the phenotypic differentiation of which couldbe important with respect to its prognostic implications.