Injection from the right subclavian vein shows contrast passing down a right mediastinal vein. The later runs show filling of the right atrium, proving that this is a right SVC which has an anomalous origin, rather than the azygos vein. A left SVC is also seen.
Injection of the left SVC shows a ventricle. The last frames show filling of the pulmonary artery, proving that this is the right ventricle, not the left. The PICC line can safely be left in this position.