Inadvertent Left Superior Vena Cava Catheterization via the Axillary Vein in a Patient With Persistent Left Superior Vena Cava.

Background: Persistent left superior vena cava (PLSVC) is a rare congenital vascular anomaly that can complicate central venous catheterization. While axillary vein cannulation is an increasingly recognized alternative to the subclavian or femoral route, inadvertent passage of a catheter into a PLSVC through the axillary vein has not been described in the literature. Case Presentation: A 46-year-old male with refractory status epilepticus required multiple intravenous infusions. Jugular and femoral access was contraindicated due to behavioral risks and local contamination, respectively, prompting ultrasound-guided catheter placement in the left axillary vein. Initial investigations confirmed venous placement, yet a chest X-ray suggested an aberrant catheter trajectory near the left hilum. Review of past imaging revealed a PLSVC draining into the coronary sinus, explaining the unusual line path. The malpositioned catheter was removed without incident, and access was successfully re-established via the internal jugular vein. Conclusion: This case stresses the importance of recognizing and evaluating unexpected catheter pathways, as variant venous anatomy can complicate central venous access. While routine imaging prior to every cannulation is impractical, prompt investigation of an atypical catheter track is essential to minimize complications. Clinicians should be aware of PLSVC in patients with unusual radiographic findings, including when using the axillary vein for central access.