One of the first inferior vena cava (IVC) filters to be approved for retrieval by the US Food and Drug Administration was the Gnther-Tulip IVC filter (Cook Medical Inc, Bloomington, IN). These IVC filters can be safely withdrawn after 12 weeks of implantation, according to clinical experience. According to recent data, the retrieval failure rate increases as the indwelling time increases. We present a case of a Gnther-Tulip IVC filter that was successfully removed 3334 days after implantation. Even after a lengthy indwelling period, it is technically possible to remove the Gnther-Tulip IVC filter.
What components make up a Gunther Tulip filter?
[62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73] This nonferromagnetic Conichrome filter has a hook for retrieval at the apex and is conical in shape. It contains four 44 mm legs with barbed hooks for anchoring, and a total of 12 wires for clot trapping are wrapped around the primary legs to form a tulip-petal shape. The maximum diameter and height are 30 mm and 50 mm, respectively. Different packages for femoral or jugular approaches are available for the introducer system, which has an 8.5F ID. The retrieval system exclusively uses a jugular approach and has a 7F ID (7F OD for the sheath).
The angle of the hook is one element that affects the likelihood that the Gnther Tulip filter will be successfully retrieved. Particularly if filter tilting is anticipated, Millward et al. advise orienting the hook toward the IVC lumen. Additionally, these writers suggest anticoagulation for 24-48 hours prior to retrieval.
Before retrieval, a venacavogram must be done to determine how much trapped clot there is. Retrieval is prohibited if there is more than 25% of a clot trapped in the cone. Additionally, the filter must not be retrieved if it is still needed or if it is physically impossible to do so due to a trapped thrombus, adherence to the IVC wall, or filter tilt. Total caval occlusion rates are reported to be 0–6%.
The recommended retrieval period is the first 12 days, however several authors have extended the retrieval period by up to 3–4 weeks—or even longer—with or without moving the filter.
Smouse et al. published a report on a multicenter experience with 554 patients in 2009. Out of 275 patients, 248 (90.2%) had their filters successfully recovered.
[74] The typical stay was 58.9 days (range, 3-494 d). According to their data, there was a higher than 94 percent chance of a successful retrieval at 12 weeks and a higher than 67 percent chance at 26 weeks.
[74] Tissue ingrowth and excessive filter tilt are the main reasons why retrieval attempts fail.
What is the purpose of an IVC filter?
A tiny device called an inferior vena cava (IVC) filter can prevent blood clots from traveling up into the lungs. In the center of your body, there is a sizable vein called the inferior vena cava. The quick operation involves inserting the gadget.
The blood channels known as veins are responsible for returning waste materials and oxygen-poor blood to the heart. The blood channels known as arteries transport nutrients and oxygen-rich blood to the body. A blood clot that develops in a vein deep within the body is known as a deep vein thrombosis (DVT). Blood thickens and collects together to form clots. This clot typically develops inside a deep vein in the thigh or lower leg.
Tiny valves found in the veins of your legs keep blood flowing back up toward your heart. But one or more of these valves could be harmed by a DVT. They deteriorate or start to leak as a result of this. Your legs begin to swell with blood as a result. Additionally, if you are sedentary for an extended period of time, this may occur. Normally, as the muscles of the leg contract, the blood moves up in the veins. The likelihood that blood cells will congregate and form a clot rises when blood travels through veins very slowly.
DVT is a significant medical condition that can make your leg swell, hurt, and feel painful. A deep clot in a leg vein occasionally gets loose and lodges in a lung vessel. A pulmonary embolism, which is a vascular obstruction, may result from this. A pulmonary embolism may result in extreme breathlessness or possibly sudden death.
One way to help avoid pulmonary embolism is with an IVC filter. The main vein returning oxygen-poor blood from the lower body to your heart is called the inferior vena cava (IVC). The blood is subsequently pumped by the heart to the lungs where oxygen is added. A tiny, wiry device called an IVC filter. The blood passes past the filter once it is implanted in your IVC. Blood clots are stopped from ascending to the heart and lungs by the filter, which traps them. By doing this, a pulmonary embolism is avoided.
A little incision is made in a vein in your neck or groin to insert the IVC filter. This vein is used to implant the catheter, a thin, flexible tube. Next, the catheter is carefully inserted into your IVC. The catheter is sent together with a deflated IVC filter. The catheter is taken out but the filter is left in place. The filter then enlarges and clings to the IVC’s walls. It may be kept there indefinitely. It might be taken away in some circumstances after some time.
It’s crucial to realize that IVC filters do not offer DVT protection. DVTs are still a possibility. If you have a DVT, the filter helps shield you from a potentially fatal pulmonary embolism.
What varieties of IVC filters are there?
Vena cava filters come in two basic varieties: permanent and retrievable. It’s critical to develop a plan for deleting retrievable IVC filters as soon as further protection is no longer required.
What components make up a Greenfield filter?
Conical in design, the original Greenfield filter has six strands of 0.015-in, zigzag-shaped, 316L-grade stainless steel legs arranged in a radial array, each with a hook at the end to secure the filter to the IVC. The 4.6 cm-long steel struts are attached to an apical hub that is pointed cephalad in the patient. The base is 3.0 cm in diameter, and the legs are 11 mm apart when they are deployed. A 24F carrier with a 29.5F external diameter is used to load the filter. The right internal jugular vein or the right common femoral vein were first surgically cut down in order to install the filter. In 1984, Tadavarthy et al published the first description of the percutaneous implantation of the Greenfield filter.
The Greenfield filter’s construction allowed thrombi to fill and occlude 70% of the filter cone, or a volume of thrombus of about 4 cm3 (34.3 percent of total volume), without drastically lowering the cross-sectional area. When the cone is filled to 80% of its total capacity, there is a 64% drop in cross-sectional area. Several in vitro and in vivo experiments have shown that this filter can capture clinically relevant emboli.
Greenfield et al. published a report on their 20-year use of the Greenfield filter in 1995.
[4] Of the 642 filter installations, 4% had recurrent PE. The rate was comparable to what other authors had reported. According to Athanasoulis et alexperience .’s with 7 distinct designs, the total recurrent PE rate was 4.9%.
[5] Of the 455 patients in the group getting the standard 24F Greenfield filter, 38 (8.4%) developed recurrent PE.
[5] Kantor et al. observed that 7 (or 41 percent) of 17 patients had access site thrombosis; this proportion of thrombosis was related to the size of the delivery system.
Greenfield et al. observed that 94 of the 101 individuals they studied had a patency of the insertion site (93 percent ).
[4] The authors stated a 96 percent IVC patency rate for the same series. 30-49 percent of patients reported that the filter had moved. Greenfield et al revised the rate of migration of more than 3 mm to 8% after accounting for respiratory variance.
[4] Only a small fraction of individuals have filter tilt, crossing of the limbs, or limb breakage, and the majority of these events have no clinical repercussions.
On computed tomography (CT) scanning, extension of the filter struts beyond the IVC, which is suggestive of perforation, has been found frequently. Animal experiments were done by Proctor et al to assess the Greenfield filter’s apparent vena caval penetration.
[7] The IVC appeared to be penetrated by all filters during cavography and CT scanning. Histology showed modification of the IVC’s intimal surface and thinning of the adventitia, whereas laparoscopy was unable to show penetration.
[7] The authors also proposed that the filter’s presence resulted in IVC remodeling and adaption.
In order to make percutaneous insertion easier, the titanium Greenfield filter (TGF) was invented in 1989 as a low-profile system. As opposed to the 24F stainless steel Greenfield filter, it is built of a titanium alloy with elastic qualities that enable the filter to be placed into a 12F carrier system (SGF). The filter’s construction maintains the conical shape with its six radiating, zigzag legs.
The SGF is 46 mm in size, while the TGF is 47 mm. As opposed to the SGF’s 30 mm base, the TGF’s base measures 38 mm. The TGF weights 0.25 g as opposed to the SGF’s 0.56 g. The substance is nonthrombogenic, nonferromagnetic, and resistant to corrosion and flexion fatigue. Through a dilator system with an attached 14F sheath, the filter can be put into either the right or left femoral or jugular vein. Differently coded packages are used to supply the femoral and jugular systems.
Greenfield et colleagues discovered an unacceptable 30% rate of migration, tilting, and penetration during their early clinical investigations.
[8] The TGF has a stronger base lateral force than the SGF, which could lead to a higher rate of IVC penetration. Through evolution and development, the hooks have changed.
[9] In 1991, information about the TGF with modified hooks (TGF-MH) was reported. In 11% of patients, the migration was larger than 9 mm.
[10] In 14 percent of patients, the base diameter increased by more than 5 mm (with 1 filter penetration confirmed with CT scanning). In 8.7% of individuals, venous thrombosis at the insertion site happened.
One or more pairs of filter struts frequently cross in the TGF. In 1991, Greenfield et al. found that 8.7% of 181 cases involved this incidence.
Filter tilt or leg distribution did not appear to have a negative impact on the ability to capture clots or the frequency of recurrent PE, according to in vitro and clinical investigations by Greenfield et al. According to several publications, the filter tilt was smaller with the jugular route than with the femoral approach. The TGF has comparable clot-trapping capacity to the 24F Greenfield filter made of stainless steel. According to reports, the total recurring PE rate ranged from 3.2 to 5%, which is close to the rates observed with other filter designs.
[14] In a long-term follow-up research with 373 patients, Greenfield et al. found that the IVC was still open 97.8% of the time after TGF insertion; 2% of patients experienced thrombosis at the insertion site.
A 12F stainless steel over-the-wire Greenfield filter was created as part of the ongoing development of the Greenfield filter design to offer a lower-profile introduction system.
[11] To stop filter migration, the hook design was enhanced. In order to center the filter upon release, the guidewire is employed during the deployment of the percutaneous steel Greenfield filter (PSGF). The high incidence of TGF tilt, according to Greenfield et al., may have been brought on by the guidewire’s removal. The PSGF was granted approval by the US Food and Drug Administration (FDA) in 1995.
The original 24F SGF’s conical shape and six radiating zigzag legs are retained in the PSGF, also known as the stainless steel Greenfield filter with alternate hooks (SGF-AH), which is made of the same 316L-grade stainless steel.
[15] Rather than 17.5, the legs are now fused to the apical bead at an angle of 0 degrees. A guidewire can pass via a hole in the apical bead’s middle. The legs measure 4.9 cm (vs 4.7 cm for the TGF and 4.6 cm for the standard Greenfield filter). The base has a 3.2 centimeter diameter (vs 3.8 cm for the TGF and 3.0 cm for the standard Greenfield filter). Through a 12F carrier system, the system is preloaded differently for jugular and femoral accesses.
Due to the potential for the guidewire to become tangled between the legs close to the hook or apex, fluoroscopic control during guidewire withdrawal was advised. With this revised design, it was thought that the more crowded legs toward the apex were to blame for the frequently occurring trapping of guidewires. According to post-placement cavography and CT scan results from 1998, Johnson et al. revealed that 21 (55 percent) of 38 patients showed filter tilting of more than 15.
[16] The researchers discovered a substantial difference between filters inserted through the jugular method (12%) and filters inserted through the femoral approach (51 percent ).
[16] Kinney et al. discovered that, in their experience with 104 PSGF installations, the right jugular approach caused the least filter tilt.
Greenfield et al. published the outcomes of 600 PSGF implantations in 599 individuals in 2000.
[18] Only 0.4% of patients who received the PSGF with the modified hook had filter tilt. 5% of patients receiving the PSGF with conventional hooks had filter tilt. Up to 27% of PSGF placements with the normal hook showed filter migration of more than 20 mm, although less than 1% of PSGF placements with alternating hooks did.
[18] According to Johnson et al. and Greenfield et al., recurrent PE occurs in 2% and 2.6% of patients, respectively. According to Greenfield et al, there was 4.3 percent insertion thrombosis and a 98 percent caval patency rate.
In 1982, the Bird’s Nest filter (BNF) was created. A network of four biocompatible stainless steel wires makes up this filter (see the following image). Each wire has a diameter of 0.18 mm and is 25 cm long. The wires are secured at each end to V-shaped struts, the two legs of which are joined at an acute angle. The wires are preshaped with several nonmatching bends of a small radius. At the end of each strut, the risk of IVC perforation is reduced by a hook with a little loop stop. The latter design (released in 1986) featured 0.46-mm struts instead of the 0.25-mm ones specified in the initial plans. With this modification, the loaded filter’s size was raised from an 8F to a 12F catheter system. The introducer is 40 cm long for femoral approaches and 75 cm long for jugular approaches.