What is a titanium Greenfield inferior vena cava (IVC) filter?

Updated: Oct 31, 2020
  • Author: Gary P Siskin, MD; Chief Editor: Kyung J Cho, MD, FACR, FSIR  more...
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Answer

Titanium Greenfield filter

The titanium Greenfield filter (TGF) was introduced in 1989 as a low-profile system to facilitate the ease of percutaneous insertion. It is made of a titanium alloy with elastic properties that allow the filter to be fitted into a 12F carrier system, as opposed to the 24F stainless steel Greenfield filter (SGF). The design of the filter preserves the conical shape consisting of 6 radiating, zigzag legs.

The TGF measures 47 mm; by contrast, the SGF measures 46 mm. The base of the TGF is 38 mm, as compared with 30 mm in the SGF. At 0.25 g, the TGF is lighter than the SGF, which weighs 0.56 g. The material is resistant to flexion fatigue and corrosion, and is nonthrombogenic and nonferromagnetic. The filter can be inserted via either the right or left femoral or jugular vein through a dilator system with an attached 14F sheath. The femoral and the jugular systems are supplied with differently coded packages.

During their preliminary clinical studies, Greenfield et al found an unacceptable 30% rate of migration, tilting, and penetration. [8] The TGF has greater lateral force at the base than the SGF, which may result in a higher rate of IVC penetration. The hooks have been modified through development and evolution. [9] Experience with the TGF with modified hooks (TGF-MH) was reported in 1991. Migration was greater than 9 mm in 11% of patients. [10] There was an increase in base diameter by greater than 5 mm in 14% of patients (with 1 filter penetration confirmed with CT scanning). Venous thrombosis at the insertion site occurred in 8.7% of patients. [10]

The TGF demonstrates a tendency for crossing 1 or more pairs of filter struts. Greenfield et al reported this occurrence in 8.7% of 181 cases in 1991 [11] ; the authors reported a 10% rate of filter tilt in 1994. [12] Sweeney et al reported filter tilting in 23% of patients. [13]

In vitro and clinical studies by Greenfield et al showed that clot-trapping ability and the rate of recurrent PE appeared not to be affected adversely by filter tilt or leg distribution. Other authors suggest that the jugular approach resulted in less filter tilt than the femoral approach. The TGF provides the same degree of clot-trapping ability as the stainless steel 24F Greenfield filter. The overall recurrent PE rate was reported to be 3.2-5%, which is comparable to the rates seen with other filter designs. [14] The IVC patency rate after TGF insertion was 97.8% in a long-term follow-up study of 373 patients by Greenfield et al; insertion-site thrombosis was seen in 2% of patients. [14]


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