Tulip Filter Research Articles

On Some Analyses

There are methodological errors being made in statistical analyses, resulting in flawed results. Examples are in the studies by Hiasa et al 1 Hiasa G Hamada M Saeki A et al. Cardiac sympathetic nerve activity can detect congestive heart failure sensitively in patients with hypertrophic cardiomyopathy. Chest. 2004; 126: 679-686 Abstract Full Text Full Text PDF Scopus (15) Google Scholar and Oudiz et al. 2 Oudiz RJ Schilz RJ Barst RJ et al. Treprostinil, a prostacyclin analogue in pulmonary arterial hypertension associated with connective tissue disease. Chest. 2004; 126: 420-427 Abstract Full Text Full Text PDF PubMed Scopus (203) Google Scholar The problem is the authors’ use of two-sample t tests, analysis of variance, or analysis of covariance to compare means, which assumes the normality and equality of unknown variances in the groups considered. The Central Limit Theorem justifies normality for mean inferences, but unknown variances need not be equal, making these methods not generally applicable to comparing means. This problem is not removed by futilely 3 Kendall MG Stuart A The advanced theory of statistics. vol 2. Charles Griffin and Co., London, UK1973: 484 Google Scholar testing for the equality of variances. Function of the Günther Tulip Vena Caval FilterCHESTVol. 128Issue 3PreviewAs an interventional radiologist with a strong interest in vena caval filters, I read the evidence-based guidelines of the Seventh ACCP Conference with careful attention. In the second part of the publication, Antithrombotic Therapy for Venous Thromboembolic Disease,1 Dr. Buller and colleagues have made a citation error in Section 4.5, vena caval interruption for the initial treatment of pulmonary embolism. They state that the Günther Tulip filter (Cook; Bloomington, IN) appears to be “less satisfactory.” To support this they provide a reference from 1992. Full-Text PDF

New Optional IVC Filter for Percutaneous Retrieval - In Vitro Evaluation of Embolus Capturing Efficiency

In-vitro evaluation of a new caval filter (Cook Celect Filter) developed for delayed percutaneous retrieval in comparison to the Gunther Tulip filter. The new Celect filter is constructed on the basis of the Tulip filter and consists of 4 primary anchoring legs and additional 8 thinner secondary wires to stabilize the filter and to guarantee adequate filtering efficiency. The filtering wires are of the same amount and equal distribution as the filtering wires of the Tulip filter. The secondary wires are arranged in such a way that percutaneous filter retrieval should be possible even if the wires are incorporated into the caval wall. In a flow model (tube size ø15-, ø22- and ø30 mm), the filter was exposed to single and multiple emboli (blood clots) of different sizes (3 x 5, 3 x 10, 5 x 10, 3 x 20, 5 x 20, 7 x 10, 7 x 20 to 10 x 24 mm) to analyse the embolus capturing efficiency under different conditions including eccentric and concentric, horizontal and vertical positions in comparison to the Tulip filter. All testing was carried out in SPSS analytic software; statistical significance was assumed for p-values < 0.05. The in-vitro embolus capturing efficiency of the Celect filter proved to be equivalent to the Tulip filter. In the single-embolus test, 91.6 % of the clots were captured by the Celect filter and 87.2 % by the Tulip filter (p = 0.042). Large clots ranging from 7 x 10 to 10 x 24 mm were captured in all cases, whereas the capture rates for the 3 x 5-mm and 3 x 10-mm clots were lower. The filters captured significantly more clots in the concentric than in the eccentric location. There was no significant difference between the overall capture rates of the two filters in the multi-clot test (72.2 % vs. 75.1 %), which showed deterioration of filter function during multiple clot exposure. With the 15-mm tube, the Celect filter had a significantly higher capture rate than the Tulip filter, whereas it was lower with the ø30-mm tube. There was no significant difference between the filters in a ø22-mm tube. The pressure gradient across the filters when exposed to blood clots ranged from 4.9 - 7.4 mm Hg for the Celect filter and 5.7 - 6.8 mm Hg for the Tulip filter in the single-embolus testing. There was no significant difference in the multi-clot tests. The new Celect filter showed similar in-vitro capture properties as the Gunther Tulip filter and deserves further in-vivo testing.

Residual Thrombus within a Retrievable IVC Filter

A 67-year-old woman underwent a laparotomy for presumed cholecystitis. A duodenal mass was discovered at the time of exploration. The abdomen was closed and the patient transferred to our institution. On arrival to our institution, she was noted to have shortness of breath and a computed tomographic (CT) examination of the chest revealed right lower lobe and right middle lobe pulmonary emboli. She was given heparin for anticoagulation. As the tumor appeared to be resectable, a pancreaticoduodenectomy (Whipple procedure) was planned. It was felt that performing this procedure on an anticoagulated patient was unwise, therefore a temporary inferior vena cava filter (Gunther Tulip filter, Cook, Bloomington, IN) was placed prior to surgery. Five days later, the patient underwent an uneventful pancreaticoduodenectomy. On postoperative day 5, the patient developed a fever and an intravenous contrast-enhanced abdominal CT was obtained (Fig 1). The CT showed thrombus entrapped within the appropriately positioned filter. On postoperative day 8, the referring physician requested removal of the filter, as it was felt that she was now a candidate for therapeutic anticoagulation. Prior to removing the filter, an inferior vena cavogram (Fig 2) was performed.

Retrievable Guenther Tulip Filter Complicated by Sepsis and Retroperitoneal Hemorrhage: Successful Management by Filter Retrieval

We encountered complications of septic shock and retroperitoneal hemorrhage which occurred after implantation of a retrievable Günther Tulip filter. A 79-year-old woman was diagnosed as right femoral vein thrombosis, and a retrievable Günther Tulip filter was deployed prior to a total knee replacement surgery. However, the patient developed septicemia due to Citrobacter freundii, followed by thrombocytopenia and retroperitoneal hemorrhage. A large hematoma was formed along the lateral side of the filter struts. We considered that the filter should be removed to control retroperitoneal hemorrhage and prevent secondary infection of the hematoma. Removal of the retrievable filter was effective in managing these complications.

Placement and Retrieval of a Gunther Tulip Filter in Patients with a Free Floating Thrombus in Inferior Vena Cava

Purpose: We wanted to assess the technical feasibility and clinical efficacy of the placement and retrieval of a Gunther Tulip filter for the prevention of fatal pulmonary embolism during the management of patients with a free floating thrombus in their inferior vena cava (IVC). Materials and Methods: Six patients having a free floating thrombus in their IVC (three patients with an isolated free floating thrombus in the IVC that resulted from immobilization due to traumatic liver injury or cerebral infarction, two patients with coexisting deep vein thrombosis in the left lower extremity that was caused by May-Thurner syndrome, and one patient with coexisting deep vein thrombosis in the right lower extremity that was due to nephrotic syndrome and immobilization after hip joint replacement) underwent placement and retrieval of a Gunther Tulip filter. The placement of the filter was performed through the right internal jugular vein to prevent the risk of detachment of the thrombus during the procedure. Retrieval of filter was performed after the free floating thrombus of the IVC had disappeared on follow-up CT because of anticoagulation therapy, aspiration thrombectomy or catheter directed Urokinase thrombolysis. Results: The Gunther Tulip filter was successfully placed in the IVC in all six patients and it was retrieved after the management of the free floating thrombus. The mean duration of the placement of the filter was 11 days (range: 7-25 days). Two patients underwent placement of an iliac vein stent for the management of May-Thurner syndrome. Detachment of the free floating thrombus in the IVC and the subsequent thrombus entrapment in the filter were documented during aspiration thrombectomy or Urokinase thrombolysis in four patients. Recurrent thrombus didn't occur during the follow-up period (range: 3-20 months) in five of the six patients. In one patient, a recurrent thrombus due to the discontinuance of anticoagulation therapy was identified at the filter detachment site of the IVC on the follow-up CT 10 days after the filter retrieval, but it disappeared 15 days after proper anticoagulation therapy was done. Conclusion: Temporary Gunther Tulip filter placement is technically feasible and efficacious for the prophylaxis of pulmonary embolism in those patients with a free floating thrombus in the IVC, and particularly in those patients who will have subsequent aspiration thrombectomy or catheter directed Urokinase thrombolyis performed.

Extended Interval for Retrieval of Günther Tulip Filters

To evaluate the Gunther Tulip vena cava filter with regard to ease of placement, complications, and retrieval over long time periods. In 53 patients (ratio of men to women, 24:29; mean age, 52.8 years) retrievable Gunther Tulip filters (Vena Cava M Reye Filter Set; William Cook Europe, Denmark) were inserted. Indications included planned major surgery with recent pulmonary embolus or high pulmonary embolus risk (n = 16), extensive ilio-femoral thrombus (n = 11), deep vein thrombosis with anticoagulant complications (n = 9), breakthrough pulmonary embolus despite anticoagulant therapy (n = 4), and contraindication to anticoagulant therapy (n = 13). All patients were followed-up for immediate and long-term complications. Fifty-three filters were successfully placed in 52 of 53 patients, yielding a success rate of 98.1%. Nineteen patients underwent attempted retrieval of their filter. Sixteen of 19 retrieval procedures were successful (84%). In three patients, the filter could not be removed on attempted retrieval (extensive filter thrombus in two patients and attachment to the wall in one patient). One patient received two filters, which were both successfully retrieved at a later date. Median implantation time for retrievable filters was 34 days (range, 7-126 days). Mean follow-up for patients with permanent filters was 13 months. Two major complications (pneumothorax and break through pulmonary embolus) and three minor complications (right internal jugular vein thrombosis in two patients and transient Horner's Syndrome in one patient) were recorded. Insertion and retrieval of filters is safe and feasible. Preliminary data suggest that Gunther Tulip filter retrieval is feasible over and above the manufacturer's recommended retrieval interval of 14 days.

Early Technical and Clinical Results with Retrievable Inferior Vena Caval Filters

Deep venous thrombosis with or without subsequent pulmonary embolism is a common preventable cause of hospital death. Although anticoagulation is the accepted standard therapy for thromboembolic disease, in situations in which anticoagulation is contraindicated, interruption of the inferior vena cava (IVC) by means of percutaneous placement of a filter has become a widely used alternative. We report our initial experience with two retrievable IVC filters. Between July 2002 and April 2003, 13 patients (mean age 54 +/- 7 years; range 29-75 years) underwent percutaneous placement of either the Gunther Tulip (n = 5; Cook Inc., Bloomington, IN) or OptEase (n = 8; Cordis, Miami Lakes, FL) IVC filter. Five patients had filters placed prophylactically before major surgery. The remaining eight patients had had a contraindication to anticoagulation, and three had experienced a hemorrhagic complication as a result of anticoagulation following either a recently documented deep venous thrombosis (n = 3) or pulmonary embolism (n = 5). Filters were successfully placed in all 13 patients, with a duration of implantation ranging from 2 to 15 days. Retrieval was attempted in 12 patients (in 1 patient, permanent filtration was secondarily requested) and was achieved in 10 (84.6%) patients. In 2 patients, retrieval failure was due to device angulation within the vena cava precluding safe retrieval. In both instances, the device used was the Gunther Tulip filter. No patient developed symptomatic pulmonary embolism or insertion-site thrombosis following either filter deployment or removal. Trapped thrombus in the filters was seen in all patients. Retrieval required a mean of 6.8 minutes (range 5-10.2 minutes) of fluoroscopy time. Neither filter migration nor caval injury was observed. Temporary IVC filters are effective and are associated with a high retrieval success rate. Further study is warranted to determine the maximal duration of implantation and whether retrievable IVC filters should expand the indications for IVC filter placement.

The Günther Tulip Retrievable Filter: Prolonged Temporary Filtration by Repositioning within the Inferior Vena Cava

To report experience with the retrievable Günther Tulip filter (GTF) as a means of temporary caval filtration for the prevention of pulmonary embolism (PE) with use of a technique that prolongs filter dwell time beyond 14 days. Eighty-eight GTFs were implanted in 87 patients. The GTFs were placed with the intention of retrieval in all patients within 14 days after initial implantation. In 23 of the 87 patients (26%), there was a need to prolong temporary caval filtration beyond the recommended period of 14 days. This was successfully achieved with use of percutaneous techniques from the right internal jugular vein whereby the filter was repositioned to a different location within the inferior vena cava (IVC) before definitive device removal. Of 88 GTFs implanted in 87 patients, 70 were successfully retrieved and 18 were left in place permanently. Forty-seven filters in 46 patients were removed after initial implantation with no need for percutaneous repositioning within the IVC to prolong dwell time (mean dwell time, 13 days). In the 23 patients who required repositioning of 23 GTFs within the IVC to prolong temporary caval filtration, the mean dwell time was 34.8 days; the mean number of repositioning procedures was 1.5, the mean time between repositioning procedures was 13.8 days, and the mean fluoroscopy time was 4.4 minutes in patients in whom filter retrieval was attempted. One patient underwent placement and subsequent removal of the GTF twice for perioperative prophylaxis against PE on two separate occasions. No filters were misplaced in an unintended location or tilted (>15 degrees ) in relation to the main caval axis after deployment. In one patient, a GTF became permanently fixed in the IVC 16 days after initial implantation and could not be removed percutaneously. Nine patients had mild or moderate-sized cervical hematomas. One patient had recurrent asymptomatic PE 2 months after filter insertion. Dwell times of 14 days can be achieved in most patients before device removal. Prolongation of the dwell time beyond 14 days can be safely and easily achieved by performing percutaneous repositioning of the device within the IVC via a jugular approach.

In Vitro Study of Guide Wire Entrapment in Currently Available Inferior Vena Cava Filters

Guide wire entrapment by some older inferior vena cava (IVC) filters is known to occur, particularly with J-tipped wires. Three new IVC filters have recently been approved for use in the United States. An in vitro study was performed to compare the risk of engaging and entrapping guide wires in eight of the IVC filters currently available in the United States. Titanium Greenfield, over-the-wire stainless-steel Greenfield, Simon nitinol, Bird's Nest, Vena Tech LGM, Vena Tech LP, TrapEase, and Günther Tulip IVC filters were deployed separately in an in vitro IVC flow model. Four different wires (15-mm, 3-mm, and 1.5-mm J-tipped, and straight) were passed 100 times each through the filters (50 from a jugular approach and 50 from a femoral approach). The frequency and specific patterns of engagement of the wires by the filters were recorded. Engagement was defined as a filter/wire interaction that caused either the filter or the wire to be deformed. The second part of the experiment measured the force (in pounds) that was required to release wires that became engaged in the filters with use of an electromechanical test stand with a specially designed low-capacity load cell of 20 pounds. Entrapment was defined as inability to separate an engaged wire from the filter without damage to either the wire or filter. Guide wire engagement occurred in all filters tested with the 15-mm, 3-mm, and 1.5-mm J-tipped wires. The straight wire did not engage any of the filters. The wires engaged the TrapEase filter with the greatest frequency overall (72.8%; 291 of 400). The 15-mm J wire engaged the filters more often than the other wires (98.5%; 788 of 800), but never became entrapped in a filter. The Vena Tech LP and Günther Tulip filters did not entrap any of the wires. The TrapEase filter, the stainless-steel Greenfield filter, and the Vena Tech LGM filter entrapped the 3-mm and 1.5-mm J wires. The force required to disengage the wires from these filters exceeded 4 pounds and resulted in structural damage to the wire and/or filter. Among the IVC filters recently approved by the Food and Drug Administration, the TrapEase filter entrapped 3-mm and 1.5-mm J-tipped guide wires, whereas the Vena Tech LP and Günther Tulip filters did not. This study corroborates previously described wire entrapment by the stainless-steel Greenfield and Vena Tech LGM devices.

Artifacts of Vena Cava Filters ex vivo on MR Angiography

We evaluated magnetic susceptibility artifacts of nine types of vena cava filters in MR angiography (MRA) at 1.0T ex vivo in order to assess the filters' compatibility with MRA. Each filter (tulip filter, tulip MReye filter, stainless Greenfield filter, titanium Greenfield filter, TrapEase filter, Simon filter, LGM Vena-Tech filter, Antheor temporary filter, and Bird's nest filter) was inserted into an acrylic tube (20 or 25 mm in diameter, 15 or 30 cm in length). Gd-DTPA was poured into each tube at a concentration of 1/500 and each was placed in a water-filled container for imaging. We evaluated artifacts of the filters according to the following criteria: signal void beyond the tube, 3+; signal void within the tube but at more than one-half the diameter of the tube, 2+; and signal void within the tube but at less than one-half the diameter of the tube, 1+. We evaluated artifacts originating at the tip, intermediate portion, and distal end of the filters. We judged the artifacts as follows: tulip (3+, 3+, 3+); tulip MReye (2+, 1+, 1+); stainless Greenfield (2+, 1+, 2+); titanium Greenfield (1+, 1+, 1+); TrapEase (1+, 2+, 1+); Simon (2+, 2+, 1+); LGM (2+, 2+, 1+); Antheor (2+, 2+, 2+); and Bird's nest (3+, 3+, 3+). The numbers in parentheses refer to the degree of signal void at the tip, intermediate portion, and distal end of the filter, respectively. The tulip filter and Bird's nest filter made of 304 stainless steel caused extensive signal voids beyond the areas defined by the filters. The signal voids in the remaining seven filters were limited to within the tube. We concluded that seven of the nine filters were compatible with MRA ex vivo.

Percutaneous Retrieval of the Tulip Vena Cava Filter: Feasibility, Short- and Long-Term Changes. An Experimental Study in Dogs

To evaluate experimentally the retrievability of the Tulip inferior vena cava (IVC) filter in an in vivo study. Changes which accompany venous healing after filter retrieval were investigated. In 12 dogs, 23 filters were inserted percutaneously into the lumbar and intrahepatic segments of the IVC. Two weeks (n = 21 filters) or 3 weeks (n = 2 filters) after insertion, filter retrieval was attempted through an 11 Fr coaxial retrieval sheath system placed via the jugular vein. Follow-up studies before and after filter retrieval included cavography, computed tomography and intravascular ultrasound of the IVC. Seven dogs were killed immediately after filter retrieval to confirm short-term changes of the IVC, and 5 dogs were killed 6 months after filter retraction to evaluate long-term changes of the IVC related to filter retrieval. Post-mortem examinations and histologic specimens of the IVC were obtained to evaluate caval wall abnormalities secondary to filter removal. All but one filter were successfully retrieved 2 weeks post-implantation. However, 3 weeks after insertion, filter retrieval was impossible. There were no complications caused by filter extraction. Follow-up studies after filter retrieval revealed no significant changes in the integrity, morphology or composition of the IVC and pericaval tissue. Histologic examination 6 months after filter retrieval revealed only flimsy fibrotic intimal plaques at the sites of former hook insertion. The Tulip filter allows percutaneous insertion and retrieval up to 14 days after insertion, suggesting that it may be useful for either permanent or temporary prophylaxis against pulmonary embolism.

Günther Tulip Filter: Preliminary Clinical Experience with Retrieval

The Günther Tulip filter is a permanent filter that has a hook to permit retrieval. The authors report their preliminary clinical evaluation of the filter with regard to feasibility and safety of retrieval. Nine men and six women who ranged in age from 17 to 79 years (mean, 51 years) underwent treatment with use of the Günther Tulip filter. Patients judged to require caval interruption for < 14 days were selected to receive the filter and retrieval was planned for all patients. Indications for filter placement were: recent pulmonary embolism (PE) or proximal deep vein thrombosis (DVT) with a contraindication to anticoagulation (11 patients), massive PE treated with thrombolytic therapy (one patient), PE with heparin-induced thrombocytopenia (one patient), and prophylaxis after major trauma (two patients). Patients were followed for inferior vena cava (IVC) thrombosis, bleeding, and recurrent DVT or PE. In all nine patients in whom it was attempted, the filter was successfully snared and retrieved via a jugular approach. The mean implantation period was 8.6 days (range, 5-13 days). Retrieval required 2.2-13 minutes (mean 5.3 minutes) of fluoroscopy. No caval injuries occurred as a result of retrieval. All retrieved filters had strands of organized thrombus on the filter struts. The patients were followed for 52-285 days (mean, 115 days) after retrieval. One patient developed a recurrent DVT 230 days after retrieval. No other patients developed a recurrent DVT and no patients developed IVC thrombosis, bleeding, or PE. Six filters were not retrieved: five because of an ongoing contraindication to anticoagulation and one because the patient died of causes unrelated to the filter. This preliminary study confirms the feasibility and safety of retrieval of the Günther Tulip filter up to 13 days after implantation.

Results of a multicenter study of the retrievable Tulip Vena Cava Filter: early clinical experience.

To evaluate clinically a new, retrievable vena caval filter in a multicenter study. The Tulip filter is a stainless steel half-basket that is suitable for antegrade or retrograde insertion via an 8.5 Fr introducer sheath. The filter can be retrieved via the jugular approach using an 11 Fr coaxial retrieval system. Forty-eight filters were implanted via the femoral approach and 38 via the jugular approach in 83 patients. Follow-up examinations (plain films, colorcoded duplex sonography) were performed up to 3 years after filter insertion (mean 136 days) in 75 patients. Twenty-seven patients were screened by colorcoded duplex sonography for insertion site thrombosis. An appropriate filter position was achieved in all cases. Insertion problems occurred in 3 cases; these were not due to the filter design but to an imperfect prototype insertion mechanism that has now been modified (n = 2) or a manipulation error (n = 1). In 2 of these cases the filters were replaced percutaneously; 1 patient required venotomy for filter removal. No further complications due to filter insertion occurred. Two filters were used as temporary devices and were successfully removed after 6 and 11 days, respectively. There was 1 fatal recurrent pulmonary embolism (PE) and 2 non-fatal PE, 5 complete and 3 partial caval occlusions, and 3 caudal migrations of the filter. Insertion site venous thrombosis was not seen in the 27 patients monitored for this complication. Precise placement of the Tulip filter is feasible by either access route and the device appears mechanically stable. Further observations are needed to confirm that safe filter removal is practical up to 10 days after its insertion.

Experimental impeller fragmentation of iliocaval thrombosis under tulip filter protection: preliminary results.

To assess the efficacy of catheter fragmentation of massive caval thrombosis and of filter protection against procedure-related pulmonary embolism. In 10 sheep, a self-expanding tulip-shaped filter made from Wallstent mesh (diameter 25 mm) was introduced from the right jugular approach into the proximal inferior vena cava. Experimentally induced massive iliocaval thrombosis was fragmented by an impeller catheter (expanded diameter 14 mm), which was advanced coaxially through the sheath of the expanded filter. Post-procedural cavography and pulmonary angiography were performed to document the extent of caval recanalization and pulmonary embolism. In all cases, impeller fragmentation cleared the inferior vena cava and the iliac veins of thrombi completely. Fragments washed downstream were trapped in the filter. In two of the first cases, parts of the clots caused pulmonary embolism before the filter was in place. Further events were avoided by a modification of the experimental setup. Except for some small peripheral perfusion defects in two cases, pulmonary angiograms did not show any incidence of pulmonary embolism. Our preliminary results suggest that impeller fragmentation of iliocaval thrombi under tulip filter protection is effective and does not cause significant pulmonary embolism.

Use of a Temporary Caval Filter to Assist Percutaneous Iliocaval Thrombectomy: Experimental Results

To test a new filter design that allows coaxial insertion of thrombectomy devices and active clot removal. A prototype filter system was used in animal experiments. It is a transjugularly inserted coaxial system with a 16-F outer sheath and an inner tube that is covered by a tulip-shaped meshwork with a 22-mm diameter at its inserted end. The inner tube allows insertion of instruments up to 8 F. The filter was developed to assist with percutaneous mechanical thrombectomy in the iliofemoral and caval veins. The filter has been used as an assisting tool in nine sheep and eight pigs. It was combined with an impeller system in nine sheep for caval thrombectomy and with a hydrodynamic catheter for iliac thrombectomy in eight pigs after artificial induction of iliac or caval thrombosis. The filters captured emboli from the intervention in six of nine sheep. The amount of captured emboli was reduced within the filter cone by the impeller instrument in five of six instances. Residual thrombus was removed by closing the filter in five of six sheep. In pigs, the filter captured emboli in three cases during hydrodynamic embolectomy. Pulmonary embolization did not occur with the filter in place. After filter removal, minor pulmonary clot embolization occurred in one case. The temporary tulip filter was effective in these animal models in capturing and removing thrombus material that may dislodge from iliocaval veins during mechanical thrombectomy.

In Vitro Evaluation of Vena Cava Filters

The authors tested in vitro nine caval filters to evaluate clot-trapping capacity and transfilter pressure gradients under varying experimental conditions. The filtering efficiency of the stainless-steel Greenfield filter was evaluated in a modified flow model. A total of 2,100 clots were injected. In addition, controlled parameters simulating in vivo conditions were selected to appreciate clot-trapping capacity and pressure gradients for nine filters in horizontal and vertical positions, by using small (3 x 30 mm) and medium-sized (5 x 30 mm) clots. Statistical evaluation was performed for 3,600 clot deliveries. Depending on experimental conditions, the clot-trapping capacity of the Greenfield filter varied greatly (0%-78%) by using small and medium clots. Bird's Nest and Simon nitinol filters demonstrated the highest filtering efficiency (94%-100%) for small clots. Medium clots were effectively captured by Bird's Nest, Simon nitinol, Antheor, and Günther Tulip filters (79%-100%). Experimental parameters influence a filter's clot-trapping capacity. Bird's Nest filters demonstrated the highest clot-trapping capacity.