Three-Dimensional Imaging Defines Straddling Mitral Valve Anatomy to Allow Successful Biventricular Repair

Biventricular repair of a straddling mitral valve (MV) can involve relocating ectopic papillary muscles and chordae. However, this increases operative complexity and risks MV incompetence. We describe a nine-month-old with D-transposition of the great arteries and straddling MV. Three-dimensional imaging identified ventricular septum malposition and defined a simple repair strategy via ventricular septal defect patch closure rightward of the ectopic papillary muscle along with the arterial switch operation. This case highlights the role of 3D imaging in planning safe biventricular repair of straddling MV in an infant.