Persistent left superior vena cava can be incidental, accidental, descriptive and investigative when the left anterior cardinal veins not obliterated. Dilated coronary sinus in the absence elevated right sided filling presence, coronary sinus opacification after right arm anticubital vein injection are the trinity for left sided superior vena cava. A case of persistent left superior vena cava in a 10 year girl with a normal right superior vena cava and a persistent bridging vein brachiocephalic vein leads to formation of superior vena cava duplication.