Straddling accessory tricuspid valve: a rare cause of left ventricular outflow tract obstruction in a neonate with coarctation complex—a case report

Accessory tricuspid valve (TV) is a rare congenital anomaly usually associated with other cardiac anomalies. It is typically classified as mobile or fixed type; both are previously described as arising exclusively from the right ventricular septum. We report the first known case of a straddling accessory TV anchoring to the left ventricular outflow tract (LVOT) wall as well, causing severe LVOT obstruction in a neonate with coarctation complex.

A female neonate was diagnosed with coarctation of the aorta, ventricular septal defect (VSD), persistent left superior vena cava, aortic valve stenosis, and severe LVOT obstruction due to a membranous tissue floating within the LVOT. After initial palliation, definitive surgery including VSD closure, aortic arch repair, and LVOT obstruction relief was undertaken at 25 days of age. Intraoperatively, a papillary-like tissue with chordae was identified, extending from the anterosuperior rim of the VSD to the LVOT endocardium just below the left coronary cusp, partially adhering to the aortic valve. A diagnosis of straddling accessory TV was made, which was confirmed by histopathological examination later. She was discharged uneventfully on post-operative day 37.

This is the first reported case of a straddling accessory TV causing severe LVOT obstruction in a neonate with coarctation of the aorta with concomitant ventricular septum defect. Left ventricular outflow tract obstruction caused by straddling accessory TV was successfully relieved with complete en bloc resection of the accessory valve tissue.