Persistent left superior vena cava (PLSVC) is an uncommon vascular anomaly; however, it is the most common congenital anomaly of thoracic venous system. It is usually asymptomatic and is detected when cardiovascular imaging is performed for unrelated reasons. When a left subclavian approach is used for vascular access, its presence can complicate catheter placement within the right side of heart. Here we present a case that highlights the practical implications PLSVC. Further, we review a diagnostic approach and provide insight into the embryonic basis of this anomaly.