To evaluate the technical feasibility and clinical safety of superior vena cava (SVC) filter placement over preexisting central venous lines (CVLs) in 23 patients who had upper extremity deep venous thrombosis with contraindications to anticoagulation. A retrospective review of the images and electronic medical records of 23 patients from 2008 to 2018 with SVC filters placed over an existing central venous line was performed in a single tertiary medical center. Twenty-one filters were placed over smaller lines (<8 Fr), and two were placed over hemodialysis catheters. Venograms before and after filter placement were compared to detect any evidence of line displacement or entrapment. Medical records were reviewed to determine whether there was any difficulty during line removal. In two of five patients with dual lines, significant line displacement was noted in the left-sided lines, both lines were later removed without complications. In one patient with a hemodialysis catheter, the filter was deployed over the tip of the catheter resulting in the entrapment of one of the legs of the filter within a side hole of the line. Fourteen patients had their lines later removed 3 days to 3 months after filter placement without reported problems. Nine patients had their CVLs left in place until the patient's death or discharge to a long-term facility. SVC filter placement over preexisting CVLs seems to be technically feasible and clinically safe in patients with <8-Fr CVLs. However, placement of the filters over hemodialysis catheters can result in leg entrapment.