In vivo evaluation of the adjustable temporary venous spring filter and the RF02 temporary filter: Comparative study

Rationale and Objectives. The authors performed this study to compare the i n vivo efficacies of the temporary venous spring filter and the RF02 filter in an animal model. Materials and Methods. Either the spring filter or the RF02 filter was plac ed in the inferior vena cava of 10 pigs each, and two clots (5 x 20 mm) wer e funneled into the filters at 1-hour intervals. The second clots were funn eled without removing the first clots captured by the filters. Clot-trappin g ability, caval occlusion associated with the clot-trapping procedure, art erial blood gas concentrations, and changes in arterial and iliac venous pr essures were evaluated. Results. Placement of the RF02 filter caused elevation of iliac venous pres sure with a maximum of 2.2 mm Hg (median) (n = 13, P = .003). Placement of the spring filter parallel to venous flow enabled capture of 90% (nine of 1 0) and 100% (six of six) of the first and second clots, respectively. The R F02 filter captured clots consistently. The difference between filters was not statistically significant. Both filters equally contributed to elevatio n of iliac venous pressure (median, 9.3 and 7.2 mm Hg [n = 9] with the spri ng filter and RF02 filter, respectively). Caval occlusion occurred in 17% ( one of six) and 67% (six of nine) of animals after two clots were trapped i n the spring filter and RF02 filter, respectively (P = .06). Other paramete rs were not influenced by the clot-trapping procedure. Conclusion. Although a larger version should be developed and better stabil ity of the filter is needed, the spring filter proved to be an efficient fi ltering device and had a lower rate of caval occlusion compared with the RF 02 filter.