Straddling Accessory Tricuspid Valve: A Rare Cause of Left Ventricular Outflow Tract Obstruction in a Neonate with Coarctation Complex – A Case Report

Background 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. Case summary 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 postoperative day 37. Conclusion This is the first reported case of a straddling accessory tricuspid valve causing severe LVOT obstruction in a neonate with Coarctation of the aorta with concomitant ventricular septum defect. LVOT obstruction caused by straddling accessory TV was successfully relieved with complete en-bloc resection of the accessory valve tissue.