Double outlet right atrium-A "bridge" across the bridging leaflets.

INTRODUCTION

Mal-alignment between the inter-atrial septum (IAS) and the inter-ventricular septum (IVS) during cardiac embryogenesis results in abnormal atrioventricular (AV) connections ranging from doubleoulet left atrium (DOLA) to double outlet right atrium (DORA)1.

CASE REPORT: We report DORA resulting from partial override of the interatrial septum (IAS) across the cleft between the bridging leaflets of the left atrioventricular (AV) valve.

RESULTS

Successful surgical management with preservation of the orifice is described, leading to an unusual type of double orifice left AV valve.

DISCUSSION: The mal-alignment of the interatrial septum, resulting in it bridging the bridging leaflets, leads to an additional orifice between the RA and the LV and a unique form of right to left shunt. DORA can cause cyanosis depending on the size of the shunt and the compliance of the ventricles. Our patient was acyanotic, possibly due to the small size of the orifice and low LV compliance secondary to hypertrophy of the LV.

CONCLUSION

our case adds to the spectrum of atrial septal mal-alignment variant of DORA in the setting of AVSD without atrial and ventricular components, with RA to LV communication occurring via the smaller orifice of a left atrioventricular valve divided by the abnormal insertion of a partially overriding, mal-aligned atrial septum; a mechanism not described previously - the 'bridge' across the bridging leaflets!