Combined tricuspid atresia- AV septal defect-a rare congenital cardiac abnormality

Congenital heart diseases (CHDs) are one of the most common birth defects worldwide with a prevalence of 1%. CHDs can be classified into cyanotic and acyanotic diseases based on the presence or absence of the characteristic bluish discoloration of skin and mucus membranes. A subset of cyanotic diseases is single ventricle malformations. This group of disorders comprises 1% of all CHDs. A remarkable yet rare and underreported entity of single ventricle malformations is combined tricuspid atresia (TA) and atrioventricular (AV) septal defect which is characterized by the anatomical features of both entities. Combined TA-AV septal malformation was first anatomically described in 1953 and further explored through echocardiography and cardiac catheterization in 1987 and then 1991. Since then, no studies have been documented in the literature prompting us to share our findings.

Herein we are describing a rare and underreported cardiac lesion based of a retrospective revision of medical charts at the American University of Beirut Medical Center (AUBMC) Children's Heart Center, a tertiary medical center in the Middle East RESULTS: Out of 200 cases with confirmed single ventricle physiology, we identified a few patients with characteristics of combined TA-AV septal defect. Our patients exhibited characteristic echocardiographic findings of primum ASD, VSD, atretic RAVV, and clefted LAVV.

In short, TA-AV septal defect is a rare, underreported congenital malformation. Tracking our patients' clinical profiles will help improve our understanding of the prognosis of this entity. Our findings may also improve treatment modalities since replacing the left-sided valve is often overlooked if the defect is inaccurately diagnosed. In addition, such findings can help shed light on the embryological development of the rarely encountered variation of AV septal malformation.