New retrievable percutaneous vena cava filter: Experimentalin vitro andin vivo evaluation

Abstract

A new retrievable percutaneous vena cava filter was tested in vitro and in vivo in 15 foxhounds. In vitro, the new vena cava filter was compared with the standard Kimray-Greenfield filter and the Günther basket filter. The new filter is a stainless steel half-basket filter and is suitable for percutaneous antegrade or retrograde insertion through a 8.5 Fr introducer sheath. In vitro testing showed the filter causing no significant flow alterations and being highly effective in capturing medium- and large-sized thrombi; furthermore, fatigue testing revealed no breakage of the new filter, whereas the Günther basket filter showed breakage of the struts. In vivo studies showed no occlusion, major perforation, or filter migration during follow-up of 2 weeks to 6 months. Tilting of the filter postimplantation occurred in two out of 28 filters. Ten of 11 filters were successfully retrieved by the transjugular approach 2 weeks after implantation. The device seems to be suitable for temporary or permanent protection against pulmonary embolism.

The Günther-Tulip Retrievable IVC Filter

“…In a previous study, 1 of 11 filters implanted in dogs was irretrievable by 2 weeks after implantation because they were firmly adhered to the vessel wall. 32 The venographic profile of the irretrievable filters in the present study also indicated that the hook of the filter was attached to the vein wall. Among 6 cases of retrieval failure, 2 patients were imaged by intravascular ultrasound to reveal the reason for the unsuccessful retrieval and in each case the filter's hook was found to be attached to the IVC wall and high-intensity echograms revealed fibrin deposits around the hook (Fig 3).…”

In vitro evaluation of a new temporary venous filter: The spring filter

“…In vitro experiments have demonstrated that 100% and 95% of emboli 5 mm in diameter are trapped by the AF and the TF, respectively [7,8], whereas the GtF could capture 92% of clots 2-4 mm in diameter [13]. In contrast, a 40% failure rate with 5 • 10 mm clots was reported for the GF by Neuerburg et al [6]. The SF, GtF, FF, PF, and NF can be inserted through a narrow-caliber sheath [1,2,9,10].…”

“…Neither has this problem been encountered with the other nitinol retrievable filter described in the literature [10]. Both the AF and the GF retain the potential to tilt after deployment [6,7]. Though function may not be affected in the off-axis position [7], the retrieval hook is likely to abut against the vessel wall in this position making snaring prior to removal difficult [8].…”

“…However, such devices rely for anchorage on hooks or barbs, which penetrate the caval wall thus increasing the chance of retroperitoneal hemorrhage complicating adjuvant thrombolytic therapy [1]. Further, experimental studies have revealed that these filters are not always retrievable [6][7][8], which defeats the very purpose of selecting them over more well-established devices.…”

“…Retrievable filters can be broadly classified into two groups: dual functional (those that lie free in the inferior vena cava and hence can double as permanent filters, such as the Giinther tulip filter (GF) [6], the Amplatz filter (AF) [7], and the Teitelbaum filter (TF) [8]), and dedicated mono-functional devices that are anchored outside the body during use (the Prothia filter (PF) [1], the GUnther temporary filter (GtF) [2], the Filcard filter (FF) [9], and the Nakagawa filter (NF) [10]). From a clinical perspective, the former type (dual functional) certainly offers greater advantages: venous access is unnecessary after placement, as is replacement by a permanent filter if long-term protection from pulmonary embolism becomes desirable.…”