In Vitro Function of an Adjustable Temporary Venous Spring Filter: Comparison with the Temporary RF02 Filter and the Permanent Greenfield Vena Cava Filter 1 Junro Hosaka, MD, Sumit Roy, MD, Knut Kvernebo, MD, Ivar Enge, MD, Frode Laerum, MD Vena cava filters are used prophylactically in patients with pulmonary embolism and deep venous thrombosis (1). The devices available for clinical use are designed mainly for permanent insertion, but a number of compli- cations associated with the use of such filters have been reported (2-5). In patients with a short-term risk of pulmonary embo- lism, such as patients who have undergone total hip re- placement (6), a temporary or retrievable filter is prefer- able to a permanent filter. When aggressive intervention- al thrombolytic methods (7-9) are used to treat deep venous thrombosis, insertion of temporary filters may help keep disrupted clot fragments from causing pulmo- nary embolism (10). We have developed a temporary venous filter, the spring filter, which is designed for quick placement, easy removal, and high clot-trapping efficiency. A prior in vitro experiment indicated the potential of this filter (11). In this in vitro study, the spring filter was compared with two commercially available devices. Acad Radio11998; 5:620-625 1 From the Section for Experimental Radiology, institute for Surgical Research, The National Hospital, University of Oslo, Oslo, Norway (J.H., S.R,, I.E,, F.L.); and the Department of Cardiovascular Surgery, Ullev61 Hospital, University of Oslo, Norway (K,K.). Received February 6, 1998; revision requested April 6; revision received April 27; ac- cepted May 4, Address reprint requests to J,H,, Department of Radi- ology, Chiba-hokusoh Hospital, Nippon Medical School, 1715 Kamagari, Inba-mura, Inba-gun, Chiba, 270-1694Japan. ©AUR, 1998 620