EXPERIMENTAL EVALUATION OF A RETRIEVABLE VENA-CAVA FILTER

A new retrievable filter, consisting of a helical basket of ten stainl ess steel wires and a retrieval cable, was tested in 7 adult sheep. Th e filter was inserted into the infrarenal vena cava through a 9-F shea th and fixed subcutaneously by a stabilizing ball at the skin insertio n site. An average of 15.6 days after the filter placement, a follow-u p cavography and clot-trapping tests were performed. The filter was re trieved through a 9-F sheath. Although all of the filters were free of thrombi and all of the inferior venae cavae were patent with good flo w, two caval stenoses were noted below the filter. All 4 x 30 mm clots were trapped by the filter. Five filters were retrieved successfully; however, two filters could not be retrieved. Although these initial a nimal studies have shown this basket-type filter to be less than ideal , the development of a filter than can be successfully retrieved is es sential for expanding the application of vena cava filters.