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. Since previous anatomical studies were conducted before the advent of this technique, we revisit this malformation with the aim to identify morphological markers that may aid patient selection.

Methods: We examined 43 heart specimens: 31 with complete form and 12 with partial form of the malformation.

Results: In 16 hearts with 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 extension and the scoop was nearly symmetrical. Hearts with the extension had significantly narrower diameters of the left ventricular outflow tract [median (inter-quartile range); 22% (17% to 33%)] than complete form without the extension [38% (29% to 50%), p=.01] and partial form [43% (25% to 50%), p=.01]. However, when the diameters were stratified with scoop depth, no obvious difference was found between complete form with a deep scoop (defined as the depth of ≥60%) and those with a shallower scoop [36% (24% to 49%) vs 28% (21% to 36%), respectively, p=.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 asymmetrical configuration of the valvar leaflets and outflow tract obstruction if the “simplified” technique is applied. Therefore, the antero-superior extension should require recognition when determining its suitability.