Background: The simplified single-patch repair for atrioventricular septal defect seems an attractive alternative to conventional methods despite controversies on its suitability in hearts with a large ventricular scoop. Inasmuch as previous anatomic studies were conducted before the advent of this technique, we revisited this malformation with the aim to identify morphologic markers that may aid patient selection.
Methods: We examined 43 heart specimens: 31 with the complete form and 12 with the partial form of the malformation.
Results: In 16 hearts with the complete form, the scoop extended antero-superiorly beyond the atrioventricular junction, resulting in a skewed shape of the scoop. By contrast, none of the other hearts had such an extension and the scoop was nearly symmetric. Hearts with the extension had significantly narrower diameters of the left ventricular outflow tract (median [interquartile range]: 22% [17% to 33%]) than the complete form without the extension (38% [29% to 50%]; p = 0.01) and partial form (43% [25% to 50%]; p = 0.01). However, when the diameters were stratified with scoop depth, no obvious difference was found between the complete form with a deep scoop (defined as the depth of 60% or greater) and those with a shallower scoop (36% [24% to 49%] versus 28% [21% to 36%], respectively; p = 0.146), indicating that antero-superior extension had more impact on the tract size than scoop depth.
Conclusions: The antero-superiorly extended and skewed scoop could lead to asymmetric configuration of the valvar leaflets and outflow tract obstruction if the simplified technique is applied. Therefore, not only scoop depth but also the antero-superior extension should be recognized when repairing this lesion.