Unguarded Mitral Orifice Associated with Discordant Atrioventricular Connection, Double-Outlet Right Ventricle, and Pulmonary Atresia

Abstract

We report a case of unguarded mitral valve orifice in a newborn boy that was associated with mirror-image cardiac sidedness, ambiguous abdominal sidedness, discordant atrioventricular connection, double-outlet right ventricle, and pulmonary atresia.

A potential new constellation of defects: Unguarded mitral orifice associated with double-outlet right ventricle {I, D, D} and pulmonary atresia/stenosis

“…The only previously reported cases in the English literature were 2 autopsy cases described by Yasukochi et al [1] in 1999 and 1 case reported by Earing et al [2] in 2003. Notably, all 4 cases, including ours, were male, and all had the same segmental set and alignment of DORV {I, D, D} and similar associated malformations of pulmonary atresia or stenosis (Table 1) [1,2]. Although the third case had no identifiable spleen, mirror-image atrial sidedness and systemic veins were present, which probably basically indicated atrial situs inversus [2].…”

“…To our knowledge, only 3 cases have been reported [1,2]. We report here the possible fourth case occurring in the setting of double-outlet right ventricle (DORV) {I, D, D} (visceroatrial situs inversus [I], D-loop ventricles [D], and D-malposition of the great arteries [D]) associated with pulmonary atresia, i.e.…”

“…atrioventricular discordance associated with DORV and pulmonary atresia in situs inversus. Unexpectedly, all 4 cases, including ours, were male, and all had the identical, above-mentioned segmental set and alignment (DORV {I, D, D}) and similar associated malformations (pulmonary atresia or stenosis) [1,2]. Therefore, these limited case series might imply that the consistent association of 2 uncommon anomalies-UMO and DORV {I, D, D} with pulmonary atresia/stenosisrepresents a previously unsuspected causal relation and possibly constitutes a new constellation of defects with unique clinical implications.…”

“…Notably, all 4 cases, including ours, were male, and all had the same segmental set and alignment of DORV {I, D, D} and similar associated malformations of pulmonary atresia or stenosis (Table 1) [1,2]. Although the third case had no identifiable spleen, mirror-image atrial sidedness and systemic veins were present, which probably basically indicated atrial situs inversus [2]. Thus, so many uncommon abnormalities occur in such strikingly consistent association, and we believe that this association could be explained by a single cause rather than by coincidence alone.…”

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Unguarded mitral orifice (UMO) is an extremely rare congenital cardiac anomaly characterized by the complete absence of mitral valvar leaflets and tensor apparatus (chordae tendineae and papillary muscles) at the mitral annulus and severe thinning of the left ventricular (LV) free wall [1,2]. To our knowledge, only 3 cases have been reported [1,2].

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