Left-sided superior vena cava mimicking catheter malposition

Central venous catheter malposition can signal a thoracic venous anomaly. We report a 56-year-old man whose LIJ catheter tracked left paramediastinally; on-table venography and CT confirmed an isolated persistent left superior vena cava draining to a dilated coronary sinus. Recognition prevented futile repositioning and permitted safe therapy. While CT/MR delineate anatomy, bedside transthoracic echocardiography, specifically adding the suprasternal notch view, with optional left-arm agitated saline, usually suffices to screen for LSVC and related variants. Operators should suspect LSVC when a left-sided catheter fails to cross midline and use targeted imaging to guide management.